General Relativistic Spectra from Accretion Disks around Rapidly Rotating Neutron Stars

光纤通信中需要掌握的英文单词及缩写光纤通信中常用英文缩写ac alternating current 交变电流AM amplitude modulation 幅度调制APD avalanche photodiode 雪崩二极管ASE amplified spontaneous emission 放大自发辐射ASK amplitude shift keying 幅移键控BER bit error rate 误码率CATV common antenna cable television 有线电视CDM code division multiplexing 码分复用CNR carrier to noise ratio 载噪比CVD chemical vapour deposition 化学汽相沉积CW continuous wave 连续波DBR distributed Bragg reflector 分布布拉格反射DFB distributed feedback 分布反馈dc direct current 直流DCF dispersion compensating fiber 色散补偿光纤DSF dispersion shift fiber 色散位移光纤DIP dual in line package 双列直插EDFA erbium doped fiber amplifier 掺铒光纤激光器FDDI fiber distributed data interface 光纤数据分配接口FP Fabry Perot 法布里- 珀罗FWHM full width at half maximum 半高全宽FWM four-wave mixing 四波混频GVD group-velocity dispersion 群速度色散IM/DD intensity modulation with direct detection 强度调制直接探测LED light emitting diode 发光二极管L-I light current 光电关系MCVD Modified chemical vapor deposition 改进的化学汽相沉积MZ mach-Zehnder 马赫泽德NA numerical aperture 数值孔径NF noise figure 噪声指数NRZ non-return to zero 非归零OC optical carrier 光载波OOK on-off keying 开关键控OTDM optical time-division multiplexing 光时分复用OVD outside-vapor deposition 轴外汽相沉积OXC optical cross-connect 光交叉连接PCM pulse-code modulation 脉冲编码调制PDM polarization-division multiplexing 偏振复用PON passive optical network 无源光网络RZ return-to-zero 归零RA raman amplifier 拉曼放大器SBS stimulated Brillouin scattering 受激布里渊散射SCM subcarrier multiplexing 副载波复用SDH synchronous digital hierarchy 同步数字体系SLA/SOA semiconductor laser/optical amplifier 半导体激光器/光放大器SLM single longitudinal mode 单纵模SNR signal-to-noise ratio 信噪比SONET synchronized optical network 同步光网络SRS stimulated Raman scattering 受激拉曼散射TCP/IP transmission control protocol/internet protocol 传输控制协议/ 互联网协议TDM time-division multiplexing 时分复用TW traveling wave 行波VAD vapor-axial epitaxy 轴向汽相沉积VCSEL vertical-cavity surface-emitting laser 垂直腔表面发射激光器VPE vapor-phase epitaxy 汽相沉积WDMA wavelength-division multiple access 波分复用接入系统DWDM dense wavelength division multiplexing/multiplexer 密集波分复用/ 器FBG fiber-bragg grating 光纤布拉格光栅AWG arrayed-waveguide grating 阵列波导光栅LD laser diode 激光二极管AOTF acousto optic tunable filter 声光调制器AR coatings antireflection coatings 抗反膜SIOF step index optical fiber 阶跃折射率分布光纤GIOF graded index optical fiber 渐变折射率分布光纤Cross-talk 串音Passive component 无源器件Active component 有源器件Soliton 孤子Jitter 抖动Heterodyne 外差Homodyne 零差Transmitter 发射机Receiver 接收机Transceiver module 收发模块Birefringence 双折射Chirp 啁啾Binary 二进制Chromatic dispersion 色度色散Cladding 包层Jacket 涂层Core cladding interface 纤芯包层界面Gain-guided semiconductor laser 增益导引半导体激光器Index-guide semiconductor laser 折射率半导导引体激光器Threshold 阈值Power penalty 功率代价Dispersion 色散Attenuation 衰减Nonlinear optical effect 非线性效应Polarization 偏振Double heterojunction 双异质结Electron-hole recombination 电子空穴复合Linewidth 线宽Preamplifer 前置放大器Inline amplifier 在线放大器Power amplifier 功率放大器Extinction ratio 消光比Eye diagram 眼图Fermi level 费米能级Multimode fiber 多模光纤Block diagram 原理图Quantum limited 量子极限Intermode dispersion 模间色散Intramode dispersion 模内色散Filter 滤波器Directional coupler 定向耦合器Isolator 隔离器Circulator 环形器Detector 探测器Laser 激光器Polarization controller 偏振控制器Attenuator 衰减器Modulator 调制器Optical switch 光开关Lowpass filter 低通滤波器Highpass filter 高通滤波器Bandpass filter 带通滤波器Longitudinal mode 纵模Transverse mode 横模Lateral mode 侧模Sensitivity 灵敏度Quantum efficiency 量子效率White noise 白噪声Responsibility 响应度Waveguide dispersion 波导色散Zero-dispersion wavelength 零色散波长Free spectral range 自由光谱范围Surface emitting LED 表面发射LED Edge emitting LED 边发射LEDThermal noise 热噪声Quantum limit 量子极限Sensitivity degradation 灵敏度劣化Intensity noise 强度噪声Timing jitter 时间抖动Packaging 封装Maxwell’s equations 麦克斯韦方程组Material dispersion 材料色散Rayleigh scattering 瑞利散射Nonradiative recombination 非辐射复合Driving circuit 驱动电路Sketch 绘图Splice 接续r efractive index 折射率cladding 包层modal distortion 模式畸变GRIN fibers 渐变折射率光纤Multimode 多模SI fibers 阶跃折射率光纤Spontaneous emission 自发辐射APD 雪崩光电二极管Sensitivity 灵敏度statistical law 统计规律threshold current 阈值电流forward biased 正向偏置reverse biased 反向偏置Edge emitting LED 边发射二极管Surface emitting LED 面发射二极管Lambertian pattern 朗伯型Visible 可见infrared 红外ultraviolet 紫外carrier 载波resonant 谐振F-P Lasers 法布里-珀罗激光器longitudinal modes 纵模transverse modes 横模Population inversion 离子数反转Stimulated emission 受激辐射Positive feedback正反馈excess lose 额外损耗splice 接续depletion region 耗尽层transit time 渡越时间response time 响应时间attenuation 衰减scattering 散射bandgap 能带间隙cutoff wavelength 截止波长star couplers 星型耦合器fiber Bragg grating 光纤布拉格光栅fiber optical isolator 光纤隔离器switches 光开关linearly polarized 线偏振circularly polarized 圆偏振unpolarized 非偏振WDM 波分复用Photodetector 光探测器Photon 光子EDF，Erbium Doped Fiber 掺铒光纤EDFA 掺铒光纤放大器energy level diagram 能级图electroabsorption modulator 电吸收调制器external modulation 外调制internal modulation 内调制quantum efficiency 量子效率slope efficiency 斜率效率pump wavelength 泵浦波长spectral width 谱宽silica fibers 石英光纤V ：归一化频率source linewidth 光源线宽optic bandwidth 光带宽electrical bandwidth. 电带宽chirp 啁啾analog modulation 模拟调制digital modulation 数字调制transparent windows 透光窗口attenuation coefficient 衰减系数SNR，signal-to-noise ratio 信噪比noise figure 噪声指数responsivity 响应度。

大型仪器功能开发 (216 ~ 220)一种液体吸附原位红外表征系统郭　艳，许传芝，王　嘉，张乐芬，牛建中（中国科学院 兰州化学物理研究所 羰基合成与选择氧化国家重点实验室，甘肃 兰州　730000）摘要：将液体吸附原位红外表征系统与红外光谱仪连接，是实现原位红外反应过程的重要技术环节. 原位红外表征过程中涉及的吸附液存储于液体吸附原位红外表征系统内，对一些沸点较高的液体可以通过加热套控温操作完成吸附，并在被测物质吸附反应过程中监测其结构变化. 系统可设置多个液体吸附池，实现在同一试验过程中进行多种液体切换吸附，满足被测物质吸附不同液体蒸汽的需求，还可以使被测物质吸附液体蒸汽，对固体表面进行惰性气体前处理或氢气还原处理. 最终通过原位红外监测出反应产物，实现液体吸附原位红外表征.关键词：液体吸附；原位红外反应；吸附反应；结构变化中图分类号：O657. 33; TH74 文献标志码：B 文章编号：1006-3757（2023）02-0216-05DOI ：10.16495/j.1006-3757.2023.02.012In-Situ Infrared Characterization System of Liquid AdsorptionGUO Yan ， XU Chuanzhi ， WANG Jia ， ZHANG Lefen ， NIU Jianzhong（State Key Laboratory for Oxo Synthesis and Selective Oxidation , Lanzhou Institute of Chemical Physics , ChineseAcademy of Sciences , Lanzhou 730000, China ）Abstract ：Connecting the in-situ infrared characterization system of liquid adsorption with the infrared spectrometer is an important technical link to realize the in-situ infrared reaction process. In-situ infrared characterization process involves the adsorption liquid stored in the in-situ infrared characterization system of liquid adsorption, which can simultaneously complete the adsorption of some liquids with high boiling point by heating a set of temperature control operation, so as to achieve the monitoring of the structural changes during the adsorption reaction of the measured substances. A number of liquid adsorption tanks in the system can be set up, which can carry out a variety of liquid switching adsorption in the same experimental process to meet the adsorption of different liquid vapors by the substance under test, as well as the adsorption of liquid vapors by the substance under test and inert gas pretreatment or hydrogen reduction treatment on the solid surface. Finally, the reaction products were detected by the in-situ infrared monitoring, and the in-situ infrared characterization of the liquid adsorption was realized.Key words ：liquid adsorption ；in-situ infrared reaction ；adsorption reaction ；change of structure红外光谱广泛应用于材料学、高分子化学、生物学、环境科学等领域. 红外测试根据分子内部分子振动或转动能级的跃迁，鉴别化合物分子结构.在原位表征技术领域，常需要在反应条件下，运用各种分析测试手段对被测物质进行研究，借助各种与分析测试手段相匹配的原位池，实现在原位或反收稿日期：2022−11−26；　修订日期：2023−05−26.基金项目：中国科学院兰州资源环境科学大型仪器区域中心仪器设备功能开发技术创新项目（lz202074） [LanzhouRegional Center for Resources and Environment Science, Chinese Academy of Sciences, Large-Scale Instrument Function Development Technology Innovation Project (lz202074)]作者简介：郭艳（1984−），女，工程师，从事分子光谱分析测试相关工作，E-mail ：通信作者：牛建中（1963−），男，正高级工程师，从事大型仪器相关工作，E-mail ：.第 29 卷第 2 期分析测试技术与仪器Volume 29 Number 22023年6月ANALYSIS AND TESTING TECHNOLOGY AND INSTRUMENTS June 2023应环境条件下对物质或反应的表征. 目前，红外光谱仪只能对被测物质进行常规的分子结构测试，无法实现被测物质吸附液体蒸汽以及被测物质吸附液体后反应机理的实时探测与表征. 本设计将液体吸附原位红外表征系统与红外光谱仪的原位红外池相连，通过监测被测物质吸附液体蒸汽后的中间产物以及最终产物，得到液体吸附原位红外表征的完整数据，通过鉴别谱图特征基团结构，最终准确判断目标产物. 将液体吸附池和外接管线通过三通阀连接，通过控制三通阀方向选择被测物质所需气氛，并通过外置配气系统将外接气氛带入被测物质表面. 通过控制加热套温度调节液体吸附池内液体温度，根据不同液体沸点调整加热套温度，实现被测物质吸附液体蒸汽，有效捕捉吸附过程中间产物以及最终产物的一系列谱图.1　液体吸附原位红外表征系统[1-3]液体吸附池可实现被测物质吸附液体蒸汽以及被测物质吸附液体后反应机理的实时探测与表征. 图1为液体吸附原位红外表征系统示意图. 该池体外围可以设加热套调节液体吸附池内液体温度，根据不同液体沸点调整加热套温度，实现被测物质吸附液体蒸汽，有效捕捉吸附过程的中间产物以及最终产物的一系列谱图. 同时，液体吸附池和外接管线通过三通阀连接，通过控制三通阀方向选择被测物质所需气氛（前处理气氛或者吸附液体蒸汽），并通过外置配气系统将外接气氛带入被测物质表面.根据试验需要可设置多个液体吸附池，用于被测物质吸附液体蒸汽，对固体表面进行惰性气体前处理或氢气还原处理，还可在同一试验过程中进行多种液体切换吸附，满足被测物质吸附不同液体蒸汽的需求，最终通过原位红外监测出反应产物，实现液体吸附原位红外表征.1.1　单一气氛吸附首先在液体吸附池1内装入所需吸附液体，盖上接有三通阀10、管线5和进气管3的顶盖2，接通加热套8的加热电源. 三通阀10、13开至液体吸附池1方向，三通阀18开至连接液体吸附池1方向，然后接入外接气路，气体通过三通阀10、管线5和进气管3进入液体吸附池1. 所进入的气体通过进气管3在液体吸附池1内鼓泡，液体蒸汽通过出气管4经三通阀13、18进入原位红外池内被测物质表面，实现单一气氛吸附. 如果需要对样品进行前处理或吸附后吹扫，可以将三通阀开至相反方向实现. 单一液体吸附实物图如图2所示.1.2　多种气氛切换吸附首先，分别在液体吸附池1、7、9内装入所需吸8134213610111475121520916191722212318原位红外池图1　液体吸附原位红外表征系统示意图（1）（7）（9）液体吸附池，（2）液体吸附池顶盖，（3）进气管，（4）出气管，（5）（6）（19）~（23）管线，（8）加热套，（10）~（18）三通阀Fig. 1　Schematic of in-situ infrared liquid adsorption characterization system第 2 期郭艳，等：一种液体吸附原位红外表征系统217附液体，依次盖上液体吸附池1、7、9的顶盖和三通阀，连接所有管线. 如果需要吸附液体吸附池7内的液体蒸汽，则先关闭三通阀12、13、15、16. 将三通阀10开至液体吸附池1相反方向，三通阀12开至液体吸附池9相反方向，三通阀11开至液体吸附池7方向，三通阀14开至连接液体吸附池7方向. 三通阀17、18开至连接液体吸附池7方向. 然后接入外接气路，气体通过三通阀10，经过气体管线到达三通阀11，再进入液体吸附池7. 液体蒸汽到达三通阀14后经管线分别过三通阀17、18后进入原位红外池内被测物质表面，最终实现液体吸附池7内气氛吸附.切换吸附液体吸附池9内液体蒸汽时，需要关闭三通阀14，将三通阀11开至液体吸附池7相反方向，三通阀16、17开至液体吸附池9方向. 打开三通阀12、15，其他条件同上. 可以通过切换三通阀方向实现不同液体蒸汽吸附.液体吸附原位红外表征系统的试验过程如图3所示. 红外光谱仪内置原位红外池，原位红外池体上设有进气管线和出气管线. 测试前液体吸附池接入反应气体，液体吸附池出气管线和原位红外池进口管线连接，连接原位红外池热电偶电源，冷凝水管连接水箱（热电偶用来测试原位池置样室温度，凝水管用来维持腔帽窗片处于室温环境）等. 测试时液体吸附池内液体蒸汽通过管线进入红外原位红外池内待测物质表面，持续监测物质吸附液体过程，检测器检测到的信号经数据采集系统输出一系列红外谱图.2　应用实例2.1　仪器与试剂红外光谱仪：Bruker Vertex 70（布鲁克）；液体吸附池（研制）；原位红外池（研制）；紫外灯光源：HSX-UV300（北京纽比特科技有限公司）；CO2：纯度高于99.99%；金属有机骨架材料（metal organic frameworks, MOF）复合物（自制备）；2-(四氢呋喃-2-基)乙酸甲酯（自制备）；Ni/CeO2（自制备）；CeO2（自制备）.2.2　实例1[4-9]利用液体吸附原位红外表征系统（图1），结合原位红外池监测光催化材料在连续光照条件下的反应中间物种. 通过液体吸附原位红外表征系统引入CO2，CO2鼓泡带水汽进入原位红外池，鼓泡过程中通过光照窗口用紫外灯持续照射被测物质2 h，监测MOF复合物CO2光还原过程的红外谱图变化（如图4所示）. 由图4可见，CO2鼓泡过程中CO2的吸收峰非常强，当紫外灯照射该MOF复合物时，随着光照时间增加，1 725、1 711 cm−1处的吸收峰持续增强. 同时，在指纹区1 286、1 191 cm−1处也捕捉到非常明显的的吸收峰.2.3　实例2[10]利用液体吸附原位红外表征系统，探测2-(四氢呋喃-2-基)乙酸甲酯在Ni/CeO2与CeO2表面的吸/脱附（如图5所示）. 通过液体吸附池鼓泡2-(四氢呋喃-2-基)乙酸甲酯水汽进入原位红外池，分别监测Ni/CeO2与CeO2表面的吸/脱附红外谱图. 首先监测Ni/CeO2和CeO2在室温（R. T.）下吸附2-(四氢呋喃-2-基)乙酸甲酯水汽的过程. 吸附饱和后，转换液体吸附原位池上三通阀，在升温条件下通入氢气气氛脱附，200 ℃脱附完成，比对Ni/CeO2和CeO2吸图2　单一液体吸附池图Fig. 2　Diagram of single liquid adsorption tank 进气管线出气管线冷凝水管热电偶三通阀单个液体吸附池原位红外池红外光谱仪图3　液体吸附原位红外表征系统试验过程Fig. 3　Experimental process of in-situ infrared characterization system of liquid adsorption218分析测试技术与仪器第 29 卷附的2-(四氢呋喃-2-基)乙酸甲酯的红外谱图.由图5可见，通过液体吸附池，Ni/CeO 2表面吸附2-(四氢呋喃-2-基)乙酸甲酯水汽后，持续升温过程仍然可以看到1 600 cm −1左右明显的吸收峰. CeO 2表面吸附2-(四氢呋喃-2-基)乙酸甲酯水汽后，升温脱附过程中，1 600 cm −1左右吸收峰消失. 利用液体吸附原位红外表征系统，实现了固体表面吸脱附水汽的原位红外监测，并且通过液体吸附原位红外池上的三通阀，实现同一试验过程中水汽吸附和气体脱附的切换.I n t e n s i t y /a .u .1 700 1 6001 500 1 200Wavenumber/cm −11 100 1 00022200 ℃200 ℃R.T.R.T.图5　2-(四氢呋喃-2-基)乙酸甲酯在Ni/CeO 2与CeO 2表面的吸/脱附Fig. 5　Absorption/desorption of 2-(tetrahydrofuran-2-yl)methyl acetate on Ni/CeO 2 and CeO 2 surfaces3　结论在原位红外测试过程中，利用液体吸附原位红外表征系统，被测物质可以吸附所需液体蒸汽，实现液体和被测物质反应过程的实时监测，分析物质反应过程中的结构变化、分峰解析基团结构，从而解析液体吸附原位红外的反应机理，进而实现原位红外被测物质吸附液体时反应机理的实时探测与表征. 通过设置多个液体吸附池，不但可以进行被测物质吸附液体蒸汽，而且还可以对固体表面进行惰性气体前处理或氢气还原处理. 同时，同一试验过程中还可以进行多种液体切换吸附，满足被测物质吸附不同液体蒸汽，最终通过原位红外监测出反应产物，实现液体吸附原位红外表征.参考文献：郭艳, 许传芝, 王嘉, 等. 一种液体吸附原位红外表征系统: CN115201145A [P ]. 2022-10-18. [GUO Yan,XU Chuanzhi, WANG Jia, et al. Liquid adsorption in situinfraredcharacterizationsystem:CN115201145A [P ]. 2022-10-18.]［ 1 ］郭艳, 许传芝, 王嘉, 等. RuNi 双活性组分负载型TiO 2催化CO 2甲烷化反应研究[J ]. 现代化工，2021，41（6）：110-113, 118. [GUO Yan, XU Chuanzhi,WANG Jia, et al. RuNi dual active components sup-ported TiO 2 catalyst for CO 2 methanation [J ]. Modern Chemical Industry ，2021，41 （6）：110-113, 118.]［ 2 ］郭艳, 许传芝, 王嘉, 等. 光催化材料原位红外池系统的研制[J ]. 分析测试技术与仪器，2020，26（4）：265-269. [GUO Yan, XU Chuanzhi, WANG Jia, et al. De-velopment of in situ infrared cell system for photocata-lytic materials [J ]. Analysis and Testing Technology［ 3 ］K u b e l k a M u n kWavenumber/cm −1图4　MOF 复合物CO 2光还原过程Fig. 4　Carbon dioxide photoreduction process of MOF complex第 2 期郭艳，等：一种液体吸附原位红外表征系统219and Instruments，2020，26 （4）：265-269.]Dong F, Han W G, Guo Y, et al. CeCoOx-MNS cata-lyst derived from three-dimensional mesh nanosheetCo-based metal-organic frameworks for highly effi-cient catalytic combustion of VOCs[J]. Chemical En-gineering Journal，2021，405 ：126948.［ 4 ］Huang X S, Dong F, Zhang G D, et al. A strategy forconstructing highly efficient yolk-shell Ce@Mn@TiOx catalyst with dual active sites for low-temperature se-lective catalytic reduction of NO with NH3[J]. Chem-ical Engineering Journal，2021，419 ：129572.［ 5 ］Fu Z H, Zhang G D, Han W L, et al. The water resist-ance enhanced strategy of Mn based SCR catalyst byconstruction of TiO2shell and superhydrophobic coat-ing[J]. Chemical Engineering Journal，2021，426：131334.［ 6 ］Ling W T, Zhao H J, Wu S L, et al. A CeCoOxcore/Nb2O5@TiO2double-shell nanocage catalyst［ 7 ］demonstrates high activity and water resistance forcatalytic combustion of o-dichlorobenzene[J]. Chem-istry-A European Journal，2021，27 （40）：10356-10368.Wu S L, Zhao H J, Dong F, et al. Construction of su-perhydrophobic Ru/TiCeOxcatalysts for the enhanced water resistance of o-dichlorobenzene catalytic com-bustion[J]. ACS Applied Materials & Interfaces，2021，13 （2）：2610-2621.［ 8 ］Zhang L W, Long R, Zhang Y M, et al. Direct obser-vation of dynamic bond evolution in single-atom Pt/C3N4 catalysts[J]. Angewandte Chemie International Edi-tion，2020，59 （15）：6224-6229.［ 9 ］Zhao Z L, Gao G, Xi Y J, et al. Selective and stableupgrading of biomass-derived furans into plasticmonomers by coupling homogeneous and heterogen-eous catalysis[J]. Chem，2022，8 （4）：1034-1049.［ 10 ］220分析测试技术与仪器第 29 卷。

少数载流子瞬态光谱(MCTS)是一种用于研究半导体材料中载流子动力学特性的先进技术。

通过测量材料中载流子的寿命和迁移率等参数，可以深入了解材料的电学性质，对半导体材料的研究和应用具有重要意义。

1. MCTS的原理和方法少数载流子瞬态光谱是使用激光脉冲来激发半导体材料，然后通过光电探测器测量样品的光学响应。

在这个过程中，材料中的载流子会发生非平衡状态的激发和复合过程，这些过程会导致材料的光学性质发生变化。

通过对这些变化的测量和分析，可以得到材料中载流子的寿命、迁移率等重要参数。

MCTS通常包括时间分辨和频率分辨两种方法。

时间分辨MCTS主要通过测量载流子在光激发后的动力学过程来研究载流子的特性，而频率分辨MCTS则通过对不同频率激发光的响应来获得频率依赖的载流子动力学信息。

2. MCTS在半导体材料研究中的应用MCTS在半导体材料研究中具有广泛的应用价值。

它可以帮助研究人员深入了解材料的电学性质，包括载流子的寿命、迁移率、复合过程等。

这些参数对于半导体材料的电子器件性能具有重要影响，因此MCTS 可以为新材料的研发和性能优化提供重要参考。

MCTS还可以用于研究半导体材料中的缺陷和杂质。

通过分析载流子动力学的变化，可以推断出材料中的缺陷类型和浓度等信息，这对于材料的质量控制和改进具有重要意义。

另外，MCTS也可以用于研究半导体材料中的光学特性和光电器件的工作原理。

通过对载流子动力学的研究，可以更好地理解材料的光吸收、发光等过程，为新型光电器件的设计和优化提供重要参考。

3. MCTS的发展和未来随着半导体材料和器件的不断发展，MCTS技术也在不断完善和拓展。

近年来，一些新型的光子学和超快光学技术被应用到MCTS中，如二维电子谱学、高阶谐波产生等，使得 MCTS 在时间和频率分辨能力上有了新的突破。

这些进展为更深入地研究和理解半导体材料的载流子动力学提供了新的途径，也为半导体光电器件的性能优化提供了更多可能性。

Series 925MicroPirani™ TransducerThe Series 925 MicroPirani™ transducer is a thermal conductivity gauge based on a unique, MEMS-based (Micro-Electro-Mechanical Systems) sensor. The 925 is used for vacuum pressure measurement and offers analog voltage output, digital interface and set point relays for process controlling.The 925 Transducer offers a wide measurement range from 1x10measurement of thermal conductivity. The MicroPirani sensor consists of a silicon chip with a heated resistive element forming one surface of a cavity. A cover on top of the chip forms the other surface of the cavity. Dueto the geometry of the sensor, convection cannot take place within the cavity and consequently, the sensor is insensitive to the mounting position. Gas molecules are passed by diffusion only to the heated element wherethe heat loss of the gas is measured.ApplicationsThe 925 can be used in many differentvacuum applications within the semiconductor,analytical, and coating industries:General vacuum pressure measurementForeline and roughing pressure measurementGas backfilling measurement and controlMass spectrometer controlActivation of UHV gaugesSystem process controlControl system pressureLike all thermal conductivity sensors, the 925 is sensitive to Array gas type. To compensate for gas dependency, the MicroPiranihas a number of common gas calibrations that can beselected via the digital interface. This makes it a simplesolution for locating medium to fine leaks in vacuum systems.The 925 has RS232, RS485, and EtherCAT digitalcommunication interface for setup of transducer parametersand to provide real time pressure measurement.The 925 also has a analog pressure output of 1 VDC/decadethat can be interfaced to external analog equipment forpressure readout or controlling. Other analog outputs andcurves can be selected via the digital user interface.The 925 has up to three mechanical relays which can beused for process control, examples are interlocking valvesor pumps. The 925 compact design significantly reducesthe amount of space occupied by a vacuum gauge. This isparticularly appealling to system designers and allows for amore compact vacuum system.Dra winga lDimensionNote: Unless otherwise specified, dimensions are nominal values in inches(mm referenced).PinOutsThree (3) set point relays and dual Aout, 15 pin D Subminiature and RJ45 EtherCAT IN/OUT ConnectorsSpecificationsSensor Type MicroPirani (MEMS Thermal Conductivity) Measuring Range 1.0 x 10-5 Torr to AtmosphereSet Point Range 5.0 x 10-4 Torr to 500 TorrCalibration Gas Air, Argon, Helium, Nitrogen, Hydrogen, H2O vapor, CO2, Xenon, NeonOperating Temperature Range 0° to 40°C (32° to 104°F)Maximum Bakeout Temperature 80°C (176°F), non-operatingCommunication RS485 / RS232 (4800 to 230400 Baud)Controls Zero adjust, atmosphere adjust, pressure units, baud rate, address, factory default, gas type;set point functions: value, hysteresis, direction, enable analog output transducer status, switch,LEDtestStatus Pressure reading and units, set point, operating time, transducer temperature, user tag, model,device type, serial number, firmware and hardware versions part number, manufacturer Analog Output 1 to 9 VDC, 100W maximum output impedance, 1 volt/decadeAnalog Output Resolution 16 bitRelays (Optional) 925 - 3 relays SPDTRelay Contact Rating 1 A @ 30VAC/DC, resistiveRelay Response<100 msec maximumPower Requirements 9 to 30 VDC, < 1.5 watts maxAccuracy (Typical)1 5 x 10-4 to 10-3 Torr ±10% of Reading10-3 to 100 Torr ±5% of Reading100 Torr to atm ±25% of ReadingRepeatability (Typical)110-3 to 100 Torr ±2% of ReadingOverpressure Limit 3000 Torr absoluteInstallation Orientation AnyInternal Volume (KF16) 2.80 cm3Materials Exposed to Vacuum 304 stainless steel, Silicon, SiO2, Si3N4, Gold, Viton®,Low out gassing epoxy resinElectronic Casing and Flange 304 stainless steelWeight (KF 16) 170 gCompliance CE, ETG.5003.2080 Vacuum Pressure Gauge 1 Accuracy and repeatability are typical values measured with Nitrogen gas at ambient temperature after zero adjustment.Ordering InformationOrdering Code Example: 925-11030Code Configuration925 with Displ a yThe optional integrated touch-screen display is user configurable; the user can change pressure units, orientation and has access to set point parameters as well as gas type. The display also indicates the status of the available set point relays. Displayed reading can be seen from >5 meters away on the high contrast display.PDR900 Power Supply and DisplayThe PDR900 power supply and readout unit is a stand alone, single channel controller for use with the Series 900 digital vacuum transducers. It can be used as a stand-alone power supply readout unit or as a tool for configuration, calibration and diagnostics of system integrated transducers in OEM applications.+1-978-645-5500 I +1-800-227-8766MKS products provided subject to the US Export Regulations. Export, re-export, diversion or transfer contrary to US law (and local country law) is prohibited.mksinst ™ and MicroPirani ™ are trademarks of MKS Instruments, Inc., VCR ® is a registered trademark of Swagelok Co. Viton ® is a registered trademark of E.I Dupont Co., Inc. EtherCAT ® is a registered trademark and patented technology, licensed by Beckhoff Automation GmbH, Germany. U.S. Patent No. 6,672,171. Other patents pending.925_01/20©2020 MKS Instruments, Inc.Specifications are subject to change without notice.。

X-rayandgamma-rayemissionfrompulsarmagnetospheres a rXiv:as tr o-ph/98105v11Oct1998X-RAY AND GAMMA-RAY EMISSION FROM PULSAR MAGNETOSPHERES J.Dyks,B.Rudak Nicolaus Copernicus Astronomical Center,Rabia′n ska 8,87-100Toru′n ,Poland ABSTRACT For polar-cap models based on electromagnetic cascades induced by curva-ture radiation of beam particles we calculate broad-band high-energy spectra of pulsed emission expected for classical (～1012G)and millisecond pulsars (～109G).The spectra are a super-position of curvature and synchrotron radiation components and most of their detailed features depend signi?cantly on the magnetic ?eld strength.The relations of expected pulsed luminosity L X (between 0.1keV and 10keV)as well as L γ(above 100keV)to the spin-down luminosity L sd are presented.We conclude that spectral properties and ?uxes of pulsed non-thermal X-ray emission of some objects,like the Crab or the millisecond pulsar B1821?24,pose a challenge to the polar-cap models based on curvature and synchrotron radiation alone.On the other hand,such models may o?er an explanation for the case of B1706?44.KEYWORDS:pulsars;X-rays;gamma-rays.1.INTRODUCTION The aim of this paper is to present general features of broad-band Xγspectra expected for polar cap models with Xγemission due to curvature (CR)and syn-chrotron(SR)processes (e.g.Daugherty &Harding 1982,Daugherty &Harding 1996)and to show that the luminosity of pulsed X-rays L X inferred for some pulsars is too high when compared to their gamma-ray luminosity L γ(or to their spin-down luminosity L sd when there is no information about gamma-rays)to be understood within polar-cap models unless some unorthodox assumptions are accepted.Some of these features are only weakly model-dependent and may,therefore,play a deci-sive rolein assessing validity of polar-cap models.Details of the results presentedbelow are given by Rudak &Dyks (1998b).2.SPECTRAL PROPERTIES OF CURVATURE RADIATION For a monoenergetic injection rate function Q e of beam particles cooled via CR,their steady-state energy distribution (of a form N e ∝γ?4)ranges from an injection energy γ0down to some lower limit γbreak ,determined by the condition,that a cooling time-scale due to CR,t cr ,is shorter than a time-scale for the particle to reside in the region of e?cient CR cooling,t esc .Thecorresponding photonspectrum of CR has a form:N cr (?)∝??53.1FIGURE1.The radiation energy spectrum per logarithmic bandwidth(thick solid line).The spectrum is normalized to the energy of the parent particle,E0.Dashed line represents itsCR component,part of which(dotted line)has been reprocessed by magnetic absorption intoe±-pairs.Thin solid line is the SR component.In addition to the electromagnetic spectra,we show the spectra of e±-pairs:the line connecting?lled squares is for the energy parallelto local magnetic?eld lines(E =γ m e c2);the line connecting open squares is the initial distribution of energy perpendicular to local magnetic lines(E⊥=γ⊥m e c2).The upper panelis for B pc=109G,P=3.1×10?3s(i.e.L sd=1035erg s?1)and E0=1.08×107MeV. The lower panel is for B pc=1012G,P=5.6×10? 2s(i.e.L sd=1036erg s?1)andE0=6.68×106MeV.To?ndγbreak analytically,we can approximate t esc withρcr/c and from the condition t cr=t esc we obtain the photon energy at which the spectral break should occur:?break=93.SPECTRAL PROPERTIES OF SYNCHROTRON RADIATIONThe synchrotron radiation is emitted by e±-pairs created in the process of mag-netic absorption of high-energy photons.The character of the source function Q±of e±-pairs depends primarily on the distribution of their pitch anglesψand on the richness of the cascades.In contrast to outer-gap models,small opening angles of magnetic?eld lines above the polar cap result in con?nement of pitch angles to a narrow range of low values.In the case of B pc=109G(Fig.1,upper panel)only one generation of e±-pairs is produced.Their source function Q±is almost monoenergetic and the steady-state)results in photon spectrum energy distribution of SR-cooled pairs(N±∝γ?2⊥of SR with a well known power-law shape N sr(?)∝??3FIGURE 2.Evolution of high-energy,non-thermal luminosity across the spin-down lumi-nosity space.The long upper curve connectinglled dots is the track of gamma-ray luminos-ity Lγ(>100keV),and the long lower curveconnecting?lled squares is the track of X-rayluminosity L X(0.1?10keV),both calculatedfor a pulsar with B pc=1012G.The shortupper curve with open circles is for Lγ,andthe short lower curve with open squares is forL X,calculated for B pc=109G.The short-dashed line marks L=L sd.The long-dashedline,marking the empirical relation of Saito etal.(1998)has been added for reference.(photon index?1.9(Saito et al.1997)and1.2,respectively)the predicted ratio /Lγ?2×10?4would make Lγlarger than L sd.LX/Lγmay o?er an On the other hand,the extremely low predicted ratios of LXexplanation for the case of B1706?44,a strong gamma-ray pulsar detected with EGRET(Lγ=2.5×1034erg s?1,Thompson et al.1996)which shows no pulsed X-ray emission.Its steady X-ray emission with L X=1.3×1033erg s?1(Becker etal.1995),probably of nebular origin,far exceeds the level of the predicted pulsed component:L≈3×1029erg s?1.XACKNOWLEDGMENTSThis work has been?nanced by the KBN grant2P03D-00911.BR acknowledges travel grants2P03C00511p01and2P03C00511p04.REFERENCESBecker W.,Brazier K.T.S.,Tr¨u mper J.,1995,A&A,298,528Becker W.,Tr¨u mper J.,1997,A&A,326,682Daugherty J.K.,Harding A.K.,1982,ApJ,252,337Daugherty J.K.,Harding A.K.,1996,ApJ,458,278O’Dell S.L.,Sartori L.,1970,ApJ,161,L63Rudak B.,Dyks J.,1998a,MNRAS,295,337Rudak B.,Dyks J.,1998b,MNRAS,submittedSaito Y.,Kawai N.,Kamae T.,Shibata S.,1998,in Proc.of the International Conference on Neutron Stars andPulsars,eds.Shibazaki N.,Kawai N.et al.,Universal Academy Press, Tokyo,295Saito Y.et al.,1997,ApJ,477,L37Thompson D.J.et al.,1996,ApJ,465,385 4。

Oxidative dehydrogenation of ethylbenzene with CO 2for styrene production over porous iron-based catalystsAntonio J.R.Castro a ,1,João M.Soares b ,2,Josue M.Filho a ,1,Alcineia C.Oliveira a ,⇑,Adriana Campos c ,3,Édwin et c ,3aUniversidade Federal do Ceará,Campus do Pici-Bloco 922,Departamento de Física/Departamento de Química Analítica e Físico-Química,Fortaleza,Ceará,Brazil bUniversidade do Estado do Rio Grande do Norte,BR 110,km 48,R.Prof.Antônio Campos,Costa e Silva,Mossoró/RN,CEP 59625-620,Brazil cCETENE,Av.Prof.Luiz Freire,Cidade Universitária,Recife,Pernambuco,Brazilh i g h l i g h t s"Styrene production over porous iron-based catalysts."XRD,57Fe-Mössbauer and Raman spectroscopy,TPR and N 2adsorption–desorption measurements characterizations."FeTi showed any tendency to sintering or phase transformation whereas the other solids suffered from hard carbon deposition.a r t i c l e i n f o Article history:Received 9December 2012Received in revised form 6February 2013Accepted 7February 2013Available online 27February 2013Keywords:Porous iron oxides Characterizations Dehydrogenation Ethylbenzene Carbon dioxidea b s t r a c tPorous iron-based catalysts with different promoters (Zr,Ti or Al)have been tested in oxidative dehydro-genation of ethylbenzene with CO 2for styrene production.The catalysts were characterized by X-ray dif-fraction (XRD),57Fe-Mössbauer and Raman spectroscopy,temperature-programmed reduction (TPR)and N 2adsorption–desorption measurements,before and after the catalytic evaluation.The reactivity of iron-based catalysts toward styrene production was dependent on the structural and textural features of the solid as well as the nature of the promoter.a -Fe 2O 3and rutile TiO 2present on FeTi were converted in situ into FeTiO 3,Fe 2TiO 5and FeTi 2O 5,and these phases revealed a high styrene yield (up to 50%)in the first stage of the reaction,but lower selectivity than that exhibited by their FeZr and FeAl counterparts.How-ever,FeTi performed much better in terms of stability showing no tendency to sintering or phase trans-formation whereas the other solids suffered from hard carbon deposition.Ó2013Elsevier Ltd.All rights reserved.1.IntroductionOxidative dehydrogenation of ethylbenzene with CO 2(ODH)is a promising alternative to the industrially applied catalytic non-oxida-tive dehydrogenation due to the strong market incentive for styrene production [1].As industrial demand for styrene grows,its produc-tion via ODH of ethylbenzene is assuming great importance.Indeed,styrene is of interest to the petroleum industry for the production of polystyrene,styrene–butadiene rubber,fibers and resins [2].How-ever,the major challenges associated with the dehydrogenation are requirement of developing selective and stable catalysts,since the deactivation of the solids due to coke formation is inevitable.In another context,iron-based compounds have been recog-nized as important materials due to their wide range of applica-tions,such as ion exchangers,material science,pharmaceuticals,biotechnology,adsorbents,catalysts and recently in nanomedicine [2–7].In the field of catalysis,many studies have been conducted concerning the use of iron-based compounds as catalysts or cata-lytic supports [8–10]due to their desirable properties,including redox abilities,acidic features and low-cost.Among the various types of iron-based compounds,porous iron oxides are suitable as catalytic active sites for a variety of reactions [10–13].Moreover,they have a much higher surface area than con-ventional microporous iron oxides and possibilities a larger pore size distribution and a more availability for their surface function-alities [11].Indeed,the pores are often used as catalytic reactors [10].Therefore,research efforts have been mainly focused on developing porous iron monoxides or iron-based compounds to improve the resistance against the deactivation resulting from car-bon deposition and increase the adsorption properties [8–12].0016-2361/$-see front matter Ó2013Elsevier Ltd.All rights reserved./10.1016/j.fuel.2013.02.019Corresponding author.Tel./fax:+558533669008.E-mail address:alcineia@ufc.br (A.C.Oliveira).1Tel./fax:+558533669008.2Tel./fax:+558433152196.3Tel./fax:+558133347224.However,porous binary iron oxides are not easy to obtain owing to the facile deposition of the second labile species to be added during the synthesis on the iron specie,which could act as a support.This is a drawback concerning the production of mixed iron-based oxi-des and requires special synthesis conditions or reactants for con-trolling pore size and shape and avoiding pores’blocking.In case of ODH to obtain styrene by using iron-based catalysts, nearly all of the transition metals and lanthanides have been stud-ied as electronic,structural and textural promoters,giving rise to good catalytic activity[9–14].Titanium,zirconium and aluminum are leading the subjects in this area of research.Although Fe is more susceptible to reduction,and therefore to deactivation than metals oxides such as Al,Zr and Ti,a combination of the latter spe-cies in a porous iron oxide would be useful to improve the catalytic performance.Most of the studies are devoted to the synthesis con-ditions and characterizations,and only a few of them deeply inves-tigated the resultant binary iron oxides porosity effect in the dehydrogenation of ethylbenzene with CO2.The influence of the active promoters on the physicochemical properties of iron-based catalysts has been investigated in this study.The effect of iron oxide porosity and phases formed on the styrene production explain the different catalytic behavior of the solids.2.Experimental2.1.Preparation of the solidsAluminum tri-sec-butoxide(Al(OC4H9sec)3)and ferric nitrate Fe(NO3)39H2O,were used as precursors to prepare the FeAl solid, according to a previously published work[15].The hydrolysis reac-tion took place by introducing aluminum tri-sec-butoxide into ex-cess of ethanol at60°C under vigorous stirring.Briefly,the synthesis was carried out by adding in a drop wise manner a mix-ture of2.9mol of water,ferric nitrate and6.5mol of absolute eth-anol to the stirred mixture of aluminium,to obtain the clear sol, which turned into a gelatinous precipitate within few minutes. The reactants were maintained under constant stirring and reflux-ing for24h.The gel was afterwards,washed with ethanol,dried at room temperature and calcined at600°C under airflow at a heat-ing rate of5°C minÀ1during2h.The abovementioned methodol-ogy was used to obtain the FeZr and FeTi,in which the zirconium oxychloride,ZrOCl2Á8H2O,and titanium(IV)isopropoxide,Ti(OiPr)4 were the active component precursors.The metal contents mea-sured by chemical analyses were80:20wt%,respectively for iron and the second metal added to the solid.2.2.Characterization of the solidsX-ray powder diffraction(XRD)patterns were recorded in a PANalytical X’PERT HighScore’s diffractometer.The Cu K a radia-tion was used and diffractrograms were collected with a2h step of0.02and a counting time of10s per step.Diffraction peaks re-corded between3°and80°have been used to identify the structure obtained at40kV and30mA.Particles size were calculated by Scherrer formula(D=K k/B cos h),where K=0.9,k=0.15418nm,h is the Bragg angle,and B is the full width at half maximum of dif-fraction peaks.The diffractograms were compared to that of ICDD database(International Centre for Diffraction Data).The Brunauer–Emmett–Teller(BET)method was employed to measure the specific surface of oxides through the nitrogen adsorption–desorption isotherms.The measurements were made atÀ196°C using a Micromeritics instrument.The samples were outgassed for6h at200°C under vacuum,prior to the sorption analyses.The temperature-programmed reduction experiments(H2-TPR) were carried out in home-made equipment.About80mg of cata-lyst was embedded in afixed-bed quartz tube and heated under nitrogen at100°C for2h.Subsequently,the reactor was cooled down to room temperature and was then heated from room tem-perature to1000°C using a heating rate of10°C minÀ1in the pres-ence of a8%H2/N2mixture.Raman spectroscopy was used to obtain information about the structural features of the solids under ambient conditions on a al-pha300microscope from Witec spectrometer.The confocal microscopy was used with a532nm laser line for the spectral exci-tation and a power of10mW.Mössbauer spectra were measured on powdered spent solids at room temperature with the spectroscopy system from Wissel.The measurements were carried out by standard transmission geome-try,using a constant acceleration spectrometer with a radioactive source of57Co in Rh matrix and activity of50mCi.The spectra werefitted using the Fit routine,which makes use of a set of Lorentzian profile peaks.The analyses allowed the calculation of amplitude and width(G)of each peak,isomer shift(d),electric quadrupole splitting(D)and hyperfine magneticfields(BFH).In addition,all isomer shifts(d)refer to metallic iron(a-Fe)at room temperature.2.3.Catalytic evaluationCatalytic reaction of dehydrogenation of ethylbenzene using CO2was carried out in afixed bed quartz reactor by using 100mg of catalyst.Ethylbenzene(EB)was fed to the reactor by passing the gas feed e.g.,nitrogen(11mmol hÀ1),and carbon diox-ide(58mmol hÀ1)over an ethylbenzene saturator vessel with a EB feed rate of1.9mmol hÀ1.The reaction tests were performed at 550°C under atmospheric pressure and a CO2/EB=30:1.The prod-ucts formed were analyzed with an FID gas chromatograph(Simple Chrom)using a capillary column.A detailed description of the cat-alytic tests evaluation is given in the references[10,11,16].The performance of catalysts was evaluated by means of the EB conver-sion,the styrene selectivity and styrene yield and the formulae are shown in the papers previously published[8,16].3.Results and discussion3.1.Structural features of the fresh catalysts3.1.1.XRD and Raman measurementsXRD patterns of the catalysts are shown in Fig.1.The diffraction lines for fresh catalysts corresponding to the(110),(012),(113) and(300)reflections of rhombohedral symmetry of hematite(a-Fe2O3,space group R3c,D63d,ICDD no.33-664)and those having characteristic reflections along(220),(311),(400)and(440)from cubic maghemite(c-Fe2O3,space group of P4332,ICDD no.39-1346)[17]phase are observed for all solids.Indeed,XRD patterns are broad and weak due to the nanocrystalline features of the sol-ids,as summarized in Table1.For FeZr,tetragonal ZrO2(space group P42/nmc,ICDD no.37-1484)is the sole zirconium specie observed in the XRD pattern,be-sides the aforesaid iron-based monoxides.In case of FeAl,even though FeAl2O4formation could be likely under the synthesis con-ditions[15,18],the XRD pattern of the fresh solid reveals only c-Fe2O3,c-Al2O3(space group and ICDD no.29-0063)and a-Fe2O3 phases and does not show any Fe–Al–related species.FeAl difracto-gram is shown in our previous paper[15].The diffractogram of FeTi shows not well resolved diffraction peaks at interplanar spacings of3.24,1.89and1.66Åcorrespond-ing to the(110),(111)and(211)characteristic reflections of theA.J.R.Castro et al./Fuel108(2013)740–748741rutile phase of TiO2in accordance with the ICDD no.21-1276, space group P42/mnm.Low intensities peaks mainly at2h equal to48.1°,which is indexed to the(200)plane arises from the tetragonal TiO2in anatase form(ICDD no.21-1272).Also,some peaks of a-Fe2O3and c-Fe2O3are found over FeTi.It is known that FeTiO3ilmenite structure is derived from that of a-Fe2O3and the ilmenite is possibly formed in an either amorphous or crystalline state by replacing every other layer of Fe3+(ionic radius0.64Å) atoms in the(001)planes by a layer of Ti4+(ionic radius0.68Å) atoms during the co-precipitation of Fe/Ti mixed oxides[19].How-ever,no XRD peaks of ilmenite are observed for FeTi due to its broad diffraction lines.Raman spectrum of FeZr(Fig.1b)shows the typical vibration modes of hematite.As stated above,a-Fe2O3belongs to the D63d space group and the phonon lines at about212,247,293,299, 412,498and613cmÀ1and additional broad modes at1050and 1319cmÀ1should appear in the Raman spectrum of hematite and maghemite[15,20].Indeed,earlier reports have shown that the latter modes are due to two magnons scattering created on close antiparalell spin sites[19,20].Thus,the modes appear around 146,225,296,411,503,607,660,869,1050and1319cmÀ1 confirming the presence of hematite and maghemite.In contrast, c-Fe2O3is an inverse spinel and its structure can be read as an iron deficient form of magnetite(Fe3O4),possessing three broad vibra-tional modes at about350,500and700cmÀ1[15].Thus,c-Fe2O3 modes could be assigned in the observed spectrum,in accordance with XRD results.In addition,the tetragonal form of ZrO2(D154h space group)has Raman modes at about270,315,455,602and 645cmÀ1whereas the monoclinic ones possesses modes at192, 335,347,382,476,617and638cmÀ1[21].Thus,the presence of ZrO2in both tetragonal and monoclinic forms is suggested for FeZr by Raman measurements.These results are in line with the ZrO2in tetragonal phase found by XRD.For FeAl and FeTi,two broad and not well defined bands are ob-served in the200–600cmÀ1and700–900cmÀ1ranges.These modes overlap each other,and thus their assignations correspond742 A.J.R.Castro et al./Fuel108(2013)740–748to the superimposed modes values for c -Fe 2O 3and a -Fe 2O 3.More-over,Raman modes of either Al 2O 3or TiO 2are not observed at all.Considering that there are few Raman studies on the influence of the Ti and Al promoters in porous iron oxide catalysts available in literature,it is difficult to explain the exact meaning of the superimposition of the modes in this study.Nevertheless,it is pos-sible to explain that the Fe–O vibrations were perturbed by the variations the chemical bonds energy,besides other effects caused by the presence of the promoters.3.1.2.N 2adsorption–desorption analysesTextural properties of the solids are evaluated by N 2adsorp-tion–desorption experiments.The isotherms as well as the corre-sponding pore size distribution curves are plotted in Fig.2.As it can be seen,the isotherm of FeAl is of type IV,with a hys-teresis in the 0.48P /P o region,which is typical of mesoporous materials.Moreover,the well-defined hysteresis loop associated with irreversible capillary condensation on mesopores from 0.4to 1.0indicates the existence of a mesoporosity arising from non-crystalline voids and spaces formed by interparticle contacts in the catalysts.FeZr exhibits a type II isotherm,with a more pro-nounced capillary condensation step that shifts to a higher P /P o and posses a hysteresis loop between H 3and H 4[22].BET surface area of FeTi and FeAl are calculated to be 421and 418m 2g À1(Table 1),respectively.The BJH pore size distribution confirms that FeZr pos-sesses a well-developed mesoporosity besides meso and macrop-ores (Fig.2b included),FeZr displays the representative type II and IV curves,with a capillary condensation step at P /P o 0.4–0.6re-gion,similar to that obtained for sol–gel based-zirconia solids [23].Additionally,the pore size distribution of FeAl is narrower than that of FeTi,implying that the latter has a more open pore structure with mesopores size and volumes of 33Åand 0.67cm 3g À1,respec-tively.Different from FeTi and FeAl,the prominent hysteresis loop of FeZr is mainly characterised by a micro-meso-macroporous structure.Indeed,the pore sizes of FeZr are centred at 12,33and 62Å,with respect to its broad pore size distribution for micro,meso and macroporoes,respectively.Moreover,the micropore area is not reported because either the micropore volume is negative or the calculated external surface area is larger than the total surface area.The relatively low textural parameters of FeAl were expected to be related to its crystalline feature.Due to this fact,the non-crystallized or tiny particles of the FeAl 2O 4phase would block the inter-particle spaces among crystalline a -Fe 2O 3and c -Fe 2O 3,which eventually resulted in the decrease of exposed internal sur-face area of entire solid.3.1.3.H 2-TPR profilesTPR analyses are used to predict the reducibility of the solids.TPR profiles (Fig.3)reveal,not unexpectedly,two reduction stages,which are typical of iron-based solids.The low hydrogen consump-tion peaks observed at temperatures of 200–400°C characterizes the Fe 3+to Fe 2+reduction while the high hydrogen consumption peaks above 600°C are attributed to the reduction of Fe 2+to Fe o [8,24].Based on XRD and Raman characterizations,the former peak can be assigned to the reduction of the free c -Fe 2O 3and a -Fe 2O 3Table 1Physicochemical and catalytic properties of the solids in dehydrogenation of ethylbenzene with CO 2.Catalyst PhasesaBET Surface area (m 2g À1)Pore volume b (cm 3g À1)Pore size b (Å)%EBconversion cFeAla -Fe 2O 33840.553027.4c -Fe 2O 3c -Al 2O 3FeZra -Fe 2O 34180.602919.8c -Fe 2O 3t-ZrO 2FeTi c -Fe 2O 3rutile TiO 2a -Fe 2O 3anatase TiO 24210.673350.5a From XRD analysis.b BJH method.cReaction conditions:CO 2/EB =30;Temperature =550o C.A.J.R.Castro et al./Fuel 108(2013)740–748743species,while the latter peaks are attributed to the reduction of the hard reducibility ZrO2and perovskite FeTiO3phases,respectively for FeZr and FeTi.In case of FeTi,the high temperature TPR peak may also be associated to the reduction of TiO2.However,TiO2is well known to be more difficult to reduce and reduction of bulk oxygen of TiO2has been reported to occur above600°C[25,26]. Besides,the Fe–Ti–O system displays a very rich phase diagram, with solid solutions including pseudobrookite(Fe1+x Ti2Àx O5), ulvöspinel-magnetite(Fe3Àx Ti x O4)and ilmenite-hematite(Fe2Àx Ti x O3).Such FeTiO3,Fe2TiO5and Fe2TiO5have been suggested to re-duce only at high temperatures(>750°C)[27].Therefore,the high hydrogen consumption peak above600°C could be attributed to both TiO2and perovskite reduction.In addition,ZrO2weakly inter-acts with iron species and provides a lesser resistance to reduction in FeZr compared to that of FeTi,thus causing the shifting of the reduction of Fe3+to lower temperatures.TPR profile of FeAl has been described previously[15]and it can be seen that the iron states of reduction are identical in terms of profiles,however,the FeAl2O4phase formation is facilitated under hydrogen environ-ment at about600°C.3.2.Catalytic resultsThe results on the ethylbenzene dehydrogenation with CO2are shown in Table1and Fig.4.The catalytic conversion of FeAl at the beginning of the reaction is slightly higher than that of FeZr and lesser than half of that of FeTi(Table1).Moreover,the styrene yield is high in thefirst min-utes of the reaction for all solids(Fig.4).It can be seen that the nat-ure of promoter present on the different iron phase is related to the porous structure and the catalytic performance,being titanium well suited to be added to the iron oxides.The fact that c-Fe2O3 and a-Fe2O3active phases are detected over all catalysts by XRD and Raman results suggest that the elevated initial conversion of the catalysts could be due to the presence of these phases.How-ever,our earlier report has demonstrated that unprompted bulk iron oxides in either hematite or maghemite forms have conver-sion values lower than2%in the steady state condition.This was attributed to the inactivity and/or ease reducibility of these oxides in the EB and CO2environments[10].Burri et al.also reported that EB conversion over either ZrO2or TiO2is inferior to that of pro-moted binaries catalysts counterparts[28];this lies to the fact that pure TiO2gives very low styrene yield in the ODH reaction[29]. Also,alumina itself performed badly in the dehydrogenation of ethylbenzene with CO2,as shown by thefindings[30–32].Since Fe2O3,ZrO2,TiO2alone or Al2O3itself are not highly actives in the reaction,the interaction between iron oxide and the aforesaid promoters might be necessary to obtain high activity.The fast decline of the selectivity of FeTi along the time on stream with respect to that of FeAl indicated an aluminum action as structural promoter of the iron oxide and this enhanced the sty-rene yield greatly[32].This is supported by the fact that there are no diffraction lines of alumina in the patterns indicating an incor-poration of Al into the iron oxide to form a nanocrystalline and sta-ble FeAl2O4.Furthermore,FeAl improves the selectivity to styrene about29%in the steady state,whereas the addition of Zr to the iron-based catalyst contributes to increase the selectivity only around18%at iso-conversion.The detection of t-ZrO2phase over FeZr reveals that zirconia particles do not stabilize the iron-based phases over the course of the reaction,which in turn resulted in a smaller activity and stability.This is confirmed by TPR results that show the easy reducibility of FeZr catalyst.The same effect is observed over Ti–Zr and Mn–Zr based catalysts for CO2dehydro-genation of ethylbenzene[28,33].The styrene yield is improved by adding aluminum to the iron oxide,but selectivity to styrene is considered low,in comparison to other aluminum-based iron oxi-des catalysts[32].The selectivity to benzene and toluene increase showing that cracking reactions are favored at high time on stream for FeAl and FeZr.The best performance of FeTi for styrene production may be rationalized from the information obtained from the characteriza-tion results.Previous studies on oxidative dehydrogenation of pro-pane reaction reveal that the TiO2phase itself is active on ethylbenzene conversion while this effect is significant over binary TiO2–ZrO2catalyst[34].The iron titanates phases are ilmenite (FeTiO3),a spinel phase(Fe2TiO4)and pseudo-brookite(Fe2TiO5) [35].Among them,FeTiO3(further shown by spent catalysts char-acterizations)is found to remain stable in the steady state,even when rutile TiO2,c-Fe2O3and a-Fe2O3were consumed,initially. Any structural change is observed(latter confirmed)and this behavior is attributed to stability of the ilmenite phase and the mesopores,which remains accessible to ethylbenzene and CO2 reactants,after the reaction.3.3.Structural features of the spent solids3.3.1.57Fe Mössbauer spectroscopyAll the catalysts exhibited structural changes after the reaction. Mössbauer spectra of the solids are shown in Fig.5.57Fe Mössbauer spectroscopy is a technique largely used to study the valence states of iron and its occupation at the unit cells sites in iron-containing crystal structures.FeAl Mössbauer spectrum isfitted with two doublets.Thefirst doublet possessing D=1.01mm sÀ1e d=0.35mm sÀ1is attributed to the presence of hematite(a-Fe2O3),which shows superpara-magnetic behavior,as a result of its nanosized particles.The secondFig.3.TPR profiles the solids.744 A.J.R.Castro et al./Fuel108(2013)740–748doublet with hyperfine parameters of ca.D=1.71mm sÀ1and d=0.92mm sÀ1corresponds well to a paramagnetic spinel type crystal structure,where only the Fe2+ions occupy tetrahedral sites, as for FeAl2O4structure[36].Therefore,FeAl has Fe3+with55.5%of the relative abundance arising from hematite while44.5%is Fe2+ originated from hercynite(FeAl2O4),which crystallizes after the catalytic test.For FeZr,Mössbauer spectrum is adjusted with one doublet and two sextets.The hyperfine parameters of the doublet(d= 0.38mm sÀ1and D=1.01mm sÀ1)are approximately the same to those found for FeAl.Taking in account this result,it can be sug-gested that superparamagnetic nanoparticles,like ZrFe2O4spinel could be present on FeZr.However,the hyperfine parameters of sextets are typical magnetite,as futher observed for FeTi.Thus, FeZr has half of the iron ions e.g.,50.6%in Fe2+state whereas the other half,49.4%is in Fe3+enviroment.Mössbauer spectrum of spent FeTi is adjusted with two dou-blets and two sextets.The two well-resolved doublets indicate the presence of paramagnetic high-spin Fe2+and Fe3+species. Mössbauer parameters obtained from the spectra are shown in Table2.Thefirst doublet of FeTi exhibits relative large isometric shift (d=1.07mm sÀ1)and quadrupole splitting(D=0.70mm sÀ1), which corresponded to a Fe2+environment.The second doublet displays relative small isometric shift(d=0.35mm sÀ1)and quad-rupole splitting(D=0.58mm sÀ1),which could be assigned to a Fe3+environment.Both doublets and their hyperfine parameters are characteristic of ilmenite(FeTiO3),in accordance with thefind-ings[37,38].In addition,the two sextets are characterized by hyperfine parameters of ca.H HF=48.93T,D=À0.06mm sÀ1and d=0.41mm sÀ1for thefirst sextet and these parameters were typ-ical Fe2+in the tetrahedral site of a spinel structure.The other sex-tet with the H HF=45.96T,D=0.02mm sÀ1and d=0.58mm sÀ1is due to Fe3+in octahedral environment.Since the inverse spinelA.J.R.Castro et al./Fuel108(2013)740–748745magnetite structure,namely,[Fe3+]tetra[Fe3+,Fe2+]octa O4,the iron is situated in the two crystallographically inequivalent tetrahedral A and octahedral B sites[15],it can be concluded that magnetite coexists with ilmenite structure for FeTi.Also,Fe2+represents 58.9%of the whole area while Fe3+composes41.1%one.3.3.2.Raman and XRDRaman measurements(Fig.6a)provide additional evidences for the catalytic behavior of the spent catalysts.Noteworthy,the modes of spent FeAl increase their intensity and shifts to lower wavenumbers compared to the fresh analogous. On the contrary of the57Fe Mössbauer analyses,Raman modes cor-responding to Fe3O4appear at200,305,530cmÀ1and a sharp mode at668cmÀ1[15,20].It is assumed that due to the modes of c-Fe2O3appears at about350,500and700cmÀ1[20],such char-acteristics modes are also observed in the Raman spectrum of FeAl.Broad bands in the200–600cmÀ1and700–900cmÀ1ranges are the main features in the FeTi and FeZr spectra,indicating that the hematite phase changed after the reaction.Raman spectra at high wavenumbers display much more in-tense and blunter modes than in low wavenumber for all solids. The modes at1300–1550cmÀ1are associated to the D and G bands,as for carbon nanotubes[16].This result suggests that the fast deactivation of FeZr and FeAl is due to the heavy coke deposi-tion whereas the slight decrease of the styrene yield on FeTi is caused by the formation of labile carbon deposits on the latter.XRD patterns of the solids are shown in Fig.6b.After the cata-lytic test,FeAl displays low-intensity reflections corresponding to the FeAl2O4phase(ICDD no.34-0192),where the(311),(440), (511),(400)planes corresponds to the2h equal to35.8,44.2, 55.0and64.3°,respectively.Peaks assigned to magnetite,maghe-mite and the two main peaks of carbon graphite at2h=31°and 64°(ICDD no.41-1487)can be identified too,which accord with the results obtained from Mössbauer.Indeed,peaks related to c-Al2O3are not observed.Judging from the broadness of the diffrac-tion lines,nanocrystalline dimensions of ca.12–17nm from the (311)plane of FeAl2O4can be found for spent FeAl,in good agree-ment with the textural properties results(Table1).FeAl2O4is a normal spinel,where one eighth of the tetrahedral sites are occu-pied by Fe2+cations whereas one half of the octahedral sites are occupied by Al3+cations[39].These obtained results are compati-ble with the fact that the solid state reaction involving Al2O3and Fe2O3in presence of CO to produce FeAl2O4and carbon species [40]occurred during the ODH reaction.Thus,the FeAl nanoparticles are confirmed to be crystalline,and sintering does not strongly affect the solid during the reaction. However,the yield of styrene decays to approximately30%in the same trend as selectivity due to the coking during the reaction. Some other studies found that the selectivity to styrene droppedTable2Parameters obtained from refinements at room temperature of Mössbauer spectra of Fe-containing samples.Electric quadrupole splitting(D),isomer shift(d),hyperfine magneticfield(BHF)and Relative spectral area(R.A.)parameters of the Fe-containing samples.Samples Electric quadrupole andisomer shiftAverage of BHF over the distributionD(mm/ s)d(mm/s)R.A.(%)H HF(T)D(mm/s)d(mm/s)R.A.(%)FeAl 1.010.3555.51.710.9244.5FeTi0.580.3229.648.93À0.060.4119.20.70 1.0739.745.960.020.5811.5FeZr 1.010.3814.649.710.000.2835.046.640.040.6850.4746 A.J.R.Castro et al./Fuel108(2013)740–748。

电化学阻抗测量锂电池老化程度Electrochemical Impedance Spectroscopy Testing on the Advanced Technology DevelopmentProgram Lithium-Ion CellsJon P. Christophersen, David F. Glenn, Chester G.Motloch, Randy B. Wright, Chinh D. HoTransportation Technologies and Infrastructure Department Idaho National Engineering and Environmental LaboratoryIdaho Falls, IDVincent S. BattagliaDOE Technical Contact Argonne National LaboratoryWashington, DCAbstract—The U.S. DOE Advanced Technology Development (ATD) Program is investigating Electrochemical Impedance Spectroscopy (EIS) as a new measure of cell degradation. As part of the program, the Idaho National Engineering and Environmental Laboratory (INEEL) is aging 18650-size cells using cycle-life tests developed under the Partnership for a New Generation of Vehicles, which has been superceded by FreedomCAR in January 2002. At beginning of life and every four weeks thereafter, cycle-life testing is interrupted for reference performance tests (RPT) to assess capacity and power fade rates. TheEIS impedance is measured at 60% state-of-charge over a range of frequencies at each RPT. The resulting Nyquist plots show that the two semi-circles, representing the anode and cathode impedance growth, are poorly resolved due to the influence of the high frequency capacitive tail and the low-frequency Warburg impedance. However, impedance growth is clearly visible at the trough frequency of the second semi-circle. The magnitude at this frequency is comparable to the standard measure of cell degradation, which is based on the percent-fade in power as a function of test time while delivering 300 Wh. The percent growth in EIS magnitude at the trough frequency highly correlates with the power fade. This suggests that the EIS test is a useful alternate measure of cell degradation.Keywords—Electrochemical Impedance Spectroscopy; trough frequency; Hybrid Pulse Power Chararacterization test; power fade; Advanced Technology DevelopmentCooperative Automotive Research). Its emphasis will be the development of fuel cell-powered vehicles. “The long-term results of this cooperative effort will be cars and trucks that are more efficient, cheaper to operate, pollution-free, and com petitive in the showroom.”It is believed that advanced high-power batteries will continue to be a critical component in this new program.]II. CELL CHEMISTRYAdvanced Technology Development testing of the second generation of cells (referred to as Gen 2 cells) is now underway. The 18650-size Gen 2 cells consist of a baseline cell chemistry and one variant chemistry (referred to as Variant C). The Baseline cells were manufactured to the following specifications, as developed by Argonne National Laboratory [2]: ?Positive Electrode? 84 wt% LiNi0.8Co0.15Al0.05O2 ? 4 wt% carbon black ? 4 wt% SFG-6? 8 wt% PVDF binder ?Negative Electrode ? 92 wt% MAG-10 ? 8 wt% PVDF binder ? ?Electrolyte? 1.2 M LiPF6 in EC/EMC (3:7 wt%) Separator? 25 μm thick PE CelgardThe Variant C cell chemistry differs from the baseline chemistry by an increase to the aluminum dopant from 5% to 10% and a decrease to the cobalt from 15% to 10% in the cathode (i.e., LiNi0.8Co0.1Al0.1O2). This change resulted in a 20% drop in rated capacity (0.8 Ah) at beginning of life (BOL) compared to the Baseline cell rated capacity of 1.0 Ah. III. CELL TESTINGThe Idaho National Engineering and Environmental Laboratory (INEEL) is cycle-life testing the Gen 2 cells in twoI. INTRODUCTIONThe U.S. Department of Energy (DOE) initiated the Advanced Technology Development (ATD) Program in 1998 to address the outstanding barriers that limit the commercialization of high-power lithium-ion batteries, specifically for hybrid electric vehicle applications. As part of the program, 18650-size cells are aged using calendar- and cycle-life tests developed under the Partnership for a New Generation of Vehicles (PNGV) Power Assist goals. Reference [1] provides additional information about the ATD Program. [Note: In January 2002 at the Detroit Auto Show, Energy Secretary Spencer Abraham announced that PNGV would be superceded by the formation of a new program between the U.S. Government and the U.S. Council for Automotive Research, dubbed FreedomCAR (Freedom0-7803-7467-3/02/$17.00 ?2002 IEEE.1851temperature groups (fifteen Baseline cells at 25°C and fifteen Baseline and Variant C cells each at 45°C), as described in the cell-specific test plan [3]. Cycle-life testing is performed using the PNGV 25-Wh Power Assist profile defined in the PNGV Battery Test Manual, Revision 3 [4]. It consists of a constant power discharge and regen pulse with interspersed rest periods centered around 60% state-of-charge (SOC). The cumulative length of a single profile is 72 seconds and constitutes one cycle. This cycle is repeated continuously during life testing.At BOL and every four weeks (i.e., 33,600 cycle-life profiles) thereafter, cycle-life testing is interrupted for reference performance testing (RPT) which are used to quantify capacity and power fade rates. The RPTs consist of a C1/1 static capacity test, a low-current hybrid pulse power characterization (L-HPPC) test, a C1/25 static capacity test, and an Electrochemical Impedance Spectroscopy (EIS) test. All RPT’s are performed at 25°C. To minimize temperature fluctuations, the cells remain in environmental chambers during testing activities.The C1/1 static capacity test consists of a complete discharge at aC1 rate (i.e., 1.0 A for the Baseline cells and 0.8 A for the Variant C cells) to the minimum voltage from a fully charged cell. The C1/25 capacity test consists of a full discharge and charge at one twenty-fifth of theC1/1 rate (i.e., 40 mA for the Baseline cells and 32 mA for the Variant C cells). These tests are used to track the capacity fade rates as a function of time. The L-HPPC and EIS tests are used to track power fade rates as a function of time. These tests are discussed in detail below.The Gen 2 end-of-test (EOT) criteria are specified in [3]. The INEEL cycle-life cells are organized in three groups of fifteen, as described above. One cell from each group was sent to a diagnostic lab for evaluation after the BOL RPT was completed. Following the 4-week RPT, another two cells were removed from test and sent to diagnostic labs. The EOT criteria for the remaining 12 cells are based on equal powerfade increments such that the penultimate pair of cells are sent for diagnostic evaluation when the power fade reaches 30%. IV. L-HPPC TESTINGThe L-HPPC test is used as the standard PNGV measure of cell degradation. It consists of a constant-current discharge and regen pulse with a rest period in between over a 60-second period. Fig. 1 shows the standard L-HPPC test profile, as specified in [4]. The 18-s constant-current discharge pulse is performed at a 5C1 rate for the ATD Gen 2 cells (i.e., 5 A for the Baseline cells and 4 A for the Variant C cells). This profile is repeated at every 10% depth-of-discharge (DOD) increment, with a 1-h rest at open circuit voltage (OCV) at each DOD increment to ensure that the cells have electrochemically and thermally equilibrated.The BOL L-HPPC test is used to calculate a scaling factor known as the battery size factor (BSF). The BSF is the minimum number of cells required to meet the PNGV power and energy goals (25 kW and 300 Wh, respectively) based on a 30% BOL power margin (i.e., 25 kW * 1.3, or 32.5 kW), as specified in [4]. The 30% BOL power margin enables the cells to simultaneously meet the PNGV power and energygoals as performance degrades over time until the 30% margin is consumed. The BSF is used to scale all subsequent PNGV power and energy-based tests including the 25-Wh Power Assist cycle-life profile [4].The ATD Gen 2 Baseline and Variant C cells require an average BSF of 553 and 651, respectively. Therefore, the Variant C chemistry requires 98 more cells to meet the same power and energy goals as the Baseline cells.1.251.00Current (relative)0.750.500.250.00-0.25-0.50-0.75-1.00102030405060Time in Profile (s)Figure 1. Hybrid pulse power characterization profile.For every RPT, the L-HPPC discharge and regen pulse powers and energies removed at a C1/1 rate are calculated at each 10% DOD increment. This data are used to find the available energy swing over specified discharge and regen power levels [4]. Fig. 2 shows the resulting BSF-scaled available energy versus the BSF-scaled power for a representative Baseline cell cycle-life tested at 45°C for 44 weeks. Cell degradation is measured in terms of power fade, which is the percentloss in power at 300 Wh as a function of test time. For the cell shown in Fig. 2, the initial power at 300 Wh (rightmost curve) is 33.5 kW. Between BOL and 44 weeks, the available energy decreased monotonically with time. At 44 weeks (leftmost curve), the power dropped to 22.4 kW, resulting in a power fade of 33.1%.1800BSF-Scaled Available Energy (Wh)160014001200100080060040020000100002000030000BSF-Scaled Power (W)40000Figure 2. BSF-scaled power versus BSF-scaled energy for a representative45°C Baseline cell.0-7803-7467-3/02/$17.00 ?2002 IEEE.1852Imaginary Impedance (- jZ&#39;&#39;)The average power fades as a function of test time for all three INEEL cycle-life groups are summarized in Fig. 3. After 44 weeks of cycle-life testing, the 25 and 45°C Baseline cells show average power fades of 16.0% and 32.1%, respectively. The 45°C Variant C cells show a more rapid power fade of 25.1% after 24 weeks of cycle-life testing. Projections based on power fade rates indicate that the Variant C cells will reach the EOT criteria sooner than the 45°C Baseline cells.Power Fade (%)30%20%10%0%Baseline Cellsfrequency capacitive tail and the low-frequency Warburg impedance. Although they become progressively more distinct as the cell ages, an alternative approach for measuring cell degradation needs to be identified.0.020.0180.0160.0140.0120.010.0080.0060.0040.002000.010.02Real Impedance (ohms)0.03Figure 4. Representative 32-week EIS data with RC network model.Figure 3. Power fade as a function of test timeImaginary Impedance (- jZ&#39;&#39;)Baseline CellsINEEL Cell GroupVariant C Cells0.030.02V. EIS TESTINGThe ATD Program is investigating EIS testing as a new measure of cell degradation. The EIS test begins by 0.01discharging the cells from afully charged state to the specified OCV corresponding to 60% SOC. Following an eight-hour rest at OCV, which allows the cells to reach electrochemical equilibrium, the impedance is measured over a frequency 0range of 10 kHz to 0.01 Hz with 10 points per decade of 00.010.020.030.04frequency. INEEL conducts EIS testing with a Model 273AReal Impedance (ohms)EG&amp;G Potentiostat/Galvanostat, a Model 1260 SolartronFrequency Analyzer, and the ZPlot control software. INEELmeasures impedance using a 4-terminal connection, Figure 5. EIS Nyquist plot for a representative Baseline cell after 44 weeks of cycle life testing.eliminating the need to subtract cable impedance.Fig. 4 shows the EIS Nyquist plot after 32 weeks of cycle-life testing at 45°C for a representative ATD Gen 2 Baseline cell. This data can be modeled using four parallel RC networks connected in series. Fig. 4 also shows the outputs of each individual RC network, resulting in four distinct curves. Progressing from left to right, the first curve represents the high frequency capacitive tail (resulting from the 4-terminal connection), which is an artifact arising from apparatus contributions. The anode and cathode primarily influence the first and secondsemi-circles, respectively [5]. The leftmost curve is the Warburgimpedance, which may represent a resistance caused by the diffusion of ions.Fig. 5 shows the EIS Nyquist plot for the same cell shown in Figs. 2 and 4 at each RPT increment from BOL to 44-weeks. Data are only plotted over a frequency range of 2.5 kHz to 0.01 Hz in Fig. 5 to better show the changes in the two semi-circles as a function of test time.The ideal method of measuring cell degradation is to track the growth of these two semi-circles as a function of time. However, as shown in Fig. 5, they are poorly resolved due to the influence of the highThe EIS Nyquist plot can be divided into three different frequency bands (high-, mid- and low-frequency). The break point between the mid- and low-frequency bands is clearly located at the trough frequency. The break point between the high- and mid-frequency is more difficult to identify since the capacitive tail significantly influences the first and second semi-circles. For the analyses discussed in this paper, the break point between the high- and mid-frequency region is guesstimated at 200 Hz.Fig. 6 shows the changes in EIS magnitude as a function of test time at these three different frequency bands for the average of two representative ATD Gen 2 Baseline cells cycle-life tested at 45°C for 44 weeks. Fig. 4 identifies the location of these frequencies on the Nyquist plot. The values shown at “High-Frequency” are the averageimpedance magnitudes at 200 Hz. The mid-frequency delta magnitudes at “Mid-Frequency” are the average magnitudes at the trough frequency minus the average magnitudes at 200 Hz. The values at “Low-Frequency” are the average magnitudes at 500-7803-7467-3/02/$17.00 ?2002 IEEE.1853mHz minus the average magnitudes at 2.5 Hz (the average initial trough frequency). All three frequency bands show some growth over test time. The low-frequency band at 50 mHz showed the smallest percent growth with 7.9% from BOL to 44 weeks. The high-frequency magnitude growth was also small with a 12.3% increase over 44 weeks. The delta magnitude growth at the mid-frequency band showed the most significant growth, with 236.9% from BOL to 44 weeks. Similar results are also seen for the 25°C Baseline cells andthe 45°C Variant C cells.Delta Magnitude (mohms)1412Fig. 8 compares the average EIS magnitude growth at thesemi-circle trough with the average power fade for the INEEL ATD Gen 2 Baseline and Variant C cells. This shows that the magnitude growth is highly correlated with power fade, having R2 values greater than 0.98. The correlation is temperature dependent, with the 25°C Baseline cellsshowing a higher slope than the 45°C cells. The Baseline and Variant C cells tested at 45°C have virtually identical slopes even though the Variant C cells are projected to reach EOT sooner than the Baseline cells. This indicates that the mechanisms responsible for the power fade rate are also responsible for EIS growth.35%30%Power Fade (%)25%20%15%10%5%0%20%40%60%80%1086420High-FrequencyMid-FrequencyFrequenciesLow-FrequencyFigure 6. EIS delta magnitude for an average of two 45°C Baseline cells.0%EIS Magnitude Growth at the Trough(%)Therefore, since the majority of the impedance growth occurs at the mid-frequency band, it can be used to measure cell degradation. However, since the break point between the high- and mid-frequencyband was only guesstimated at 200 Hz, only the EIS magnitude growth at the trough frequency will be considered. For the cell shown in Fig. 5, the 44-week trough magnitude (27.2 m? at 0.5 Hz) grew 63.9% from the BOL trough magnitude (16.6 m? at 2.0 Hz). The average EIS magnitude percent-growth as a function of cycle time for all three INEEL cycle-life groups are summarized in Fig. 7. After 44 weeks of cycle-life testing, the 25 and 45°C Baseline cells show average EIS magnitude growths of 26.2% and 62.1%, respectively. The 45°C Variant C cells show a more rapid magnitude growth with 46.2% after only 24 weeks of cycle-life testing.60%40%20%0%Baseline CellsBaseline CellsINEEL Cell GroupVariant C CellsFigure 8. Magnitude growth at the semi-circle trough frequency versus powerfade.Therefore, the EIS test may be a useful alternate measure of cell degradation. It is a less intrusive alternative to L-HPPC testing since it can be performed at a single SOC and does not require fully discharging the cell at 10% DOD increments. The disadvantage to EIStesting is that no energy calculations are possible. Further studies are required to determine how the correlation between magnitude growth and power fade changes as a function of SOC (all cells shown in Fig. 8 were cycle-life and EIS tested at 60% SOC).VI. CONCLUSIONThe INEEL is cycle-life testing the ATD Gen 2 Baseline and Variant C cells. Every four weeks, cycle-life testing is interrupted for reference performance tests, which include the L-HPPC and EIS tests. From theL-HPPC test, the power fade as a function of test time is tracked as the standard measure of cell degradation. The Nyquist plots show that the majority of the impedance growth occurs at the trough frequency of the second semi-circle. The percent growth in magnitude at that frequency highly correlates with the power fade. This model shows that higher power fade rates also result in higher EIS magnitude growth rates. The model is temperature dependent, with the 25°C Baseline cells showing a higher slope than the 45°C Baseline and Variant C cells. Therefore, the EIS test provides an alternate and less intrusive method to track cell degradation. However, the EIS test does not provide any information on available energy. Since all INEEL ATD Gen 2 EIS testing is performed at 60% SOC, additional studies will be required to determine theSOC-dependence of this model.EIS Magnitude Growth (%)Figure 7. EIS magnitude growth as a function of test time0-7803-7467-3/02/$17.00 ?2002 IEEE.1854VII. ACRONYMS AND ABBREVIATIONSThe following acronyms and abbreviations were used in this paper: ATD BOL DOD DOE EOT FreedomCAR L-HPPC OCV PNGVAdvanced Technology Development beginning of life depth of discharge Department of Energy end of testFreedom Cooperative Automotive Research low-current hybrid pulse power characterization open circuit voltagePartnership for a New Generation of VehiclesRPT SOCreference performance test state of chargeBSF battery size factorACKNOWLEDGMENTThis work was prepared as an account of work sponsored by an agency of the United States Government under US DOE ContractDE-AC07-99ID13727. Funding for this work was provided by the U.S. DOE Office of Advanced Automotive Technologies.REFERENCES*1+ R.A. Sutula et al., “FY 2000 progress report for the Advanced Technology Development program,” U.S. DOE, OAAT, December 2000. *2+ Gary Henriksen, “Gen 2 Baseline &amp; Variant C cells,” ATDQuarterlyReview Presentation in Albuquerque, N.M., November, 2000.[3] PNGV test plan for Advanced Technology Development Gen 2 lithium-ion cells, EVH-TP-121, Revision 6, October 2001.[4] PNGV battery test manual, DOE/ID-10597, Revision 3, February 2001. *5+ D. Zhang at al., “Studies on capacity fade of lithium-ion batteries,”Journal of Power Sources, vol. 91, pp. 122-129, 2000.EIS electrochemical impedance spectroscopy0-7803-7467-3/02/$17.00 ?2002 IEEE.1855。