Specific heat of Ce_{0.8}La_{0.2}Al_{3} in magnetic fields a test of the anisotropic Kondo

五年级英语上册单词表_专业英语单词表词汇表Chapter-1-wordsmaterial world 物质世界distinguish 区别,辨别chemical, mechanical, electrical properties 化学、力学、电学性质physical state 物理状态plasma 等离子体apparent 显然的，外观的distinct 截然不同的，独特的diversity 差异,多样性element 元素bond 结合联结in turn 依次,轮流arise from 起于basic particle 基本粒子electrons, protons, neutrons 电子、质子、中子internal forces and energy 内力和内能gravitational, electrostatic, electromagnetic, nuclear force 引(重)力、静电力、电磁力、核力ability to do work 做功的本领(能力)stored, released, transformed, transferred, “used”energ y 能量的存储、释放、转换、转移、使用entity 实体vice versa 反之亦然review 回顾,复习recall 回忆,回想,记起product (quotient,sum, difference) 乘积(商、和、差)muscles 肌肉object 物体potential (kinetic)energy 势(动) 能rest 静止其余Newton’slaw 牛顿定律law(theorem,definition) 定律(定义、定理)mass(m),acceleration(a),speed(v)质量、加速度、速度conservation of energy 能量守恒(conversation会话；谈话)hydroelectric plant 水电厂turbine 汽轮机，涡轮机electric generator 发电机blade 叶片joule(J)焦耳friction 摩檫electrical potential difference 电位势charged particles 带电粒子automobile (motorcar) 汽车a storage battery 蓄电池mechanical parts 机械部件thermodynamics 热力学specify 详述,载明inherent 固有的,天生的convert 转变,变换petroleum 石油fossil 化石,远古生物形成的nuclear reaction 核反应intimate 亲密的, 熟悉的, 私人的fission 裂变thermometer 温度计specific heat capacity 比热macroscopic 宏观的microscopic 微观的Celsius scale 摄氏温标Kelvin scale 开氏温标translational motion 平动Boltzmann’sconstant 玻尔兹曼常数(K)proportional to 正比于appreciate 估价,理解inversely proportional to 反比于prefix 前缀,词首（postfix后缀，词尾）astronomical 天文的,极大的submicroscopic 亚微观的oscillation 振荡,振动transmitter 无线电，电视讯号发送装置X-ray X 射线gamma ra y γ射线sophisticate 改进,采用先进技术,完善gasoline 汽油dissociate 分离latent energy 潜能fusion 熔解,聚变agitation 激发,搅拌theory 理论（experiment 实验）rigor 精确special relativity 狭义相对论rest mass 静止质量impart 给予,传授startling 令人吃惊的viz. 即consume 消耗,消费magnitude 大小,数量,量级dimensions 尺寸,尺度,维(数),度(数),元efficient 有效的,效率高的discrepancy 差异,矛盾vital至关重要的,所必需的long-term 长期survival 幸存,生存crisis 危机scarce缺乏的,稀有的inequitable 不公平的Chapter-2-wordsnature n 诞生(源自拉丁语nasci) descriptive adj 描述的，起描述作用的analogy n 类似,类推retain vt 留住；保住identity 完全相同；本身；恒等式carbon monoxide 一氧化碳oxide 氧化物(ironoxide 氧化铁)dioxide 二氧化物artificially adv. 人工(man-made)atomic number n 原子序数the periodic table of the elements 元素周期表atomic weight 原子量(gramatom 克原子)Avogadro’snumber 阿弗加德罗常数turn out v. 打扫,生产,制造,关掉time 乘perfect gas law 理想气体规律(方程)bombardment n 炮击；轰击Maxwell’sgas theory 麦克斯韦气体理论Maxwellian distribution 麦克斯韦分布kinetic theory of gas 气体动力学Deduce v. 推论；推想；演绎Pressure 压力,压强Volume n. 卷,册,体积,量,大量,音量Absolute temperature 绝对温度uniform一致的；同一的；一律的；均匀的Rutherford t n 卢瑟福(物理学家,化学家)crucial adj. 极重要的；有决定性的pave the way for 为…..铺平道路in the form of 以…形式存在Emission n. 散发,发射,喷射,遗精Absorption n 吸收;专注;兼并,合并incandescent adj 白热的，白炽的Bohr n 波尔novel n. 小说,adj. 新奇的,异常的sketched n. 草图,梗概,vi. v. 勾画equality n 同等；平等centripetal adj 向心的；向心力的centrifugal adj 离心的；离心力的spontaneously adv. 自然地,本能地integers n 整数(fraction 分数小数)quantum n. 量,额,[物]量子,量子论quantum numbers 量子数radius (radiusesradii) 半径(直径diameter ) positive adj. 肯定的,正的,阳的negative n. 负数,底片;adj. 否定的,负的Shell model 壳层模型discrete adj 离散的；分立的；不连续的continuous 连续的,持续的outermost or valence shell 外层或化合价层inner shell 内层（outershell 外层）Laser 激光;激光器;［雷射］缩自lightamplification by stimulated emission of radiation phases 阶段,状态,相,相位使同步stimulate vt. 刺激,激励in step adv. 步调一致(inphases) avalanche n, v 雪崩,纷至沓来other than adv. 不同于,除了,而不是axis n. 轴,轴线proceed vi. 进行,继续下去,发生coherent adj. 一致的,相干的crystalline 结晶的,水晶的,晶态,晶体gem n. 宝石,精华,被喜爱的人,美玉ruby n. 红宝石affinity n. 密切关系,姻亲关系,亲合力neon n. [化]氖helium n. 氦（化学元素,符号为He）semiconductor n 半导体(semicircle半圆)energetic adj. 精力充沛的,高能的phonograph n. 留声机,vi. 灌入留声机dye n. 染料,染色vt. 染v. 染noise-free 没有(无)噪声hologram 全息摄影,全息图submarine n 潜艇adj 海生的；海底的reside 住，居住,（与in连用）存在于thermonuclear adj 核热能的，热核的isotopes n. 同位素hydrogen 氢deuterium 氘，重氢tritium 氚mass number 质量数atomic number 原子序数ground state 基态（excitedstates 激发态）neutral 中性的，不带电的qualitative adj 性质的；定性的quantitive =quantitative 定量的sodium n 〈化〉钠（元素符号为:Na）uranium n〈化〉铀（元素符号为：U）dimension n. 尺寸,尺度,维(数),度(数)whereas conj. 然而,反之,尽管,但是dense adj. 密集的,浓厚的range n. 行列,范围,射程vt.排列Appendix n. 附录,附属品,[解]阑尾label 标签,商标,标志vt. 贴标签于atomic mass unit 原子质单位（原子量）thumb 拇指,经验方式,作搭车手势repulsion n. 推斥,排斥,严拒,厌恶,反驳Chapter-3-wordsradioactivity n 放射性，放射现象disintegration (decay)n. 分裂,衰变mineral n. 矿物,矿石,无机物fiber 纤维；纤维质man-made fiber 人造纤维tissue n 薄纸,棉纸,[生]组织,连篇product n. 产品,产物,乘积protactinium 镤（Pa）helium 氦（He）thorium 钍（Th）neutrinos n 中微子radium 镭(Ra) polonium, bismuth 钋(Po)、铋(Bi)“chain” of disintegrations 衰变“链”positron n 正电子，阳电子negatron(electron)n. 阴电子species n. 种类,(原)核素intact adj. 完整无缺的,尚未被人碰过的,half-life 半衰期becquerel (Bq)n. [核]贝可(勒尔)activity 活度curie (Ci)居里Chapter-4-wordsnuclear processes 核过程nuclear reaction 核反应induce vt. 劝诱,促使,导致,引起,感应emphasize vt. 强调,着重v. 强调transmutation n 变形，变质，嬗变，蜕变Rutherford n. 卢瑟福(物理学家,化学家)counterpart n. 副本,配对物,对称物readily adv. 乐意地,欣然,容易地alchemist n. 炼金术士cobalt n. [化]钴(符号为Co) capture n. 捕获,战利品vt. 俘获,捕获control rods 控制棒omit vt. 省略,疏忽,遗漏compound nucleus 复合核recall vt 记起；想起；召回；取回Coulomb n. [电]库仑(电量单位)imagine vt. 想象,设想,以为probe n. 探针,探测器vt. 探查,查明apparent adj. 显然的,外观上的collision. n. 碰撞,冲突clarify v. 澄清,阐明sweep v. 打扫,清扫,冲光,扫过,掠过perpendicular adj. 垂直的,n. 垂线abpeviated v. 缩写,缩短,简化consistent adj. 一致的,调和的resonance n. 共鸣,谐振,共振,共振子boron n. [化]硼logarithmic adj. 对数的exponential migrate vi. 移动,移往,移植immigrate vt. 使移居入境vi. 移来metal 金属metalloid 非金属Actinium(Ac)锕Aluminium(Al)铝Americium(Am)镅Antimony(Sb)锑Argon(Ar)氩Arsenic(As)砷Astatine(At)砹Barium(Ba)钡Berkelium(Bk)锫Beryllium(Be)铍Bismuth(Bi)铋Boron(B)硼flux [物]流量,通量random n. adj. adv. 随机,无规则,任意elastic scattering 弹性散射inelastic scattering 非弹性散射classical physics 经典物理predominant 占主导地位的dominant adj. 占优势的,支配的light elements 轻元素heavy elements 重元素instead adv. 代替,改为,抵作,更换exceedingly adv. 非常地,极度地barn n. 靶（恩）（核反应截面单位）,农仓diminish v. (使)减少,(使)变小attenuation n. 变薄,稀薄化,变细,衰减incident n. 事件,事变penetrate vt. 穿透,渗透,看穿,洞察half-thickness 半衰减厚度(half-life半衰期)quantity n. 量,数量mean free path 平均自由程the mean life 平均寿命applicable adj. 可适用的,可应用的deflected v. (使)偏斜,(使)偏转slab n. 厚平板,厚片,混凝土路面,板层infinitesimal adj. 无穷小的n. 极微量cite vt. 引用, 引证, 提名表扬integral n. [数学]积分,完整,部分Bromine(Br)溴Cadmium(Cd)镉Caesium(Cs)铯Calcium(Ca)钙Californium(Cf)锎Carbon(C)碳Cerium(Ce)铈Chlorine(Cl)氯Chromium(Cr)铬Cobalt(Co)钴Copper(Cu)铜Curium(Cm)锔Dysprosium(Dy)镝Einsteinium(Es)锿Erbium(Er)铒Europium(Eu)铕Fermium(Fm)镄Fluorine(F)氟Francium(Fr)钫Gadolinium(Gd)钆Gallium(Ga)镓Germanium(Ge)锗Gold(Au)金Hafnium(Hf)铪Helium(He)氦Holmium(Ho)钬Hydrogen(H)氢Indium(In)铟Iodine(I)碘Iridium(Ir)铱Iron(Fe)铁Krypton(Kr)氪Lanthanum(La)镧Lawrencium(Lr)铹Lead(Pb)铅Lithium(Li)锂Lutetium(Lu)镥Magnesium(Mg)镁Manganese(Mn)锰Mendelevium(Md)钔Mercury(Hg)汞Molybdenum(Mo)钼Neodymium(Nd)钕Neon(Ne)氖Neptunium(Np)镎Nickel(Ni)镍Niobium(Nb)铌Nitrogen(N)氮Nobelium(No)锘Osmium(Os)锇Oxygen(O)氧Palladium(Pd)钯Phosphorus(P)磷Platinum(Pt)铂Plutonium(Pu)钚Polonium(Po)钋Chapter-5-wordsPotassium(K)钾Praseodymium(Pr)镨Promethium(Pm)钷Protactinium(Pa)镤Radium(Ra)镭Radon(Rn)氡Rhenium(Re)铼Rhodium(Rh)铑Rubidium(Rb)铷Ruthenium(Ru)钌Samarium(Sm)钐Scandium(Sc)钪Selenium(Se)硒Silicon(Si)硅Silver(Ag)银Sodium(Na)钠Strontium(Sr)锶Sulphur(S)锍Tantalum(Ta)钽Technetium(Tc)锝Tellurium(Te)碲Terbium(Tb)铽Thallium(Tl)铊Thorium(Th)钍Tin(Sn)锡Thulium(Tm)铥Titanium(Ti)钛Tungsten(W)钨Uranium(U)铀Vanadium(V)钒Xenon(Xe)氙Ytterbium(Yb)镱Yttrium(Y)钇Zinc(Zn)锌Zirconium(Zr)锆empace vt. 拥抱,包含,收买,信奉origin n. 起源,出身,血统,[数]原点accelerator n. 加速者,加速器cosmic rays n. 宇宙射线reactor n. 反应堆refer to 查阅,提到,谈到,涉及bulk n. 大小,体积,大批,大多数,散装biological adj. 生物学的distinguish v. 区别,辨别irradiate v. 照射content n. 内容,adj.满意的,vt. 使满足excitation n. 刺激,激励,[物]激发,励磁ionization n. 离子化,电离fluorescent adj. 荧光的,莹光的subsequent adj. 后来的,并发的displace vt. 移置,转移,取代,v. 转移resultant adj. 作为结果而发生的,合成的class n. 班级,阶级,种类,vt. 把...分类inner orbits 内层轨道transition n. 转变,转换,跃迁,过渡pemsstrahlung（德语）轫致辐射paking radiation 轫致辐射rule of thumb 单凭经验的方法heavy charged particle 重带电粒子slowing 慢化，减速fragments of fission 裂变碎片massive adj. 厚重的,大块的,结实的inertia n. 惯性,惯量hyperbolic adj. 双曲线的Photon-Electron Scattering 光电散射visualize vt. 形象,形象化,想象vi. 显现stationary 固定的，稳定的Compton effect 康普顿效应Compton scattering 康普顿散射derivation n. 引出,出处,词源deduce vt. 推论,演绎出successive adj. 继承的,连续的photoelectric effect 光电效应competition n. 竞争,竞赛dislodges v. 驱逐eliminate vt. 排除,消除v. 除去mechanism n. 机械装置,机制，机理ejection n. 喷出,排出物outer shell 外层inner shell 内层electron-positron pair production 电子对产生效应in accord with adv. 与...一致opposite adj. 相对的,相反的,n. 相反的事物reverse n. 相反, 反面, 相反的, 倒转的, vt. 颠倒annihilate vt. 消灭,歼灭electron-positron pair annihilate 正负电子对湮灭total n. 合计adj. 总的,v. 合计,总数达consequence n. 结果,推论,因果关系component n. 成分adj. 组成的,构成的carry over v. 继续,结转次页,延期至...attenuation n. 变薄,稀薄化,变细,衰减neutron reaction 中子反应in a position to adv. 能够cell n. 单元,细胞,蜂房,电池tissue n. 薄纱织品, 薄纸, 棉纸, [生]组织, 连篇primary adj. 主要的, 初级的, 原来的, 根源的secondary adj. 次要的,次级的,中级的hydrocarbon n. 烃,碳氢化合物regard A as B 把 A 视为 B radiation damage n. 辐射损伤recoil n. 后退,弹回,vi. 弹回,撤退,反冲take place v. 发生interest n. 兴趣,重要性,影响,利息tend vi. 趋向,往往是vt. 照管,护理exponential law 指数规律molecular adj. [化]分子的,由分子组significance n. 意义,重要性fission 裂变chain reaction n. 连锁反应,链式反应at present adv. 现在,目前mechanism n.机械装置,机构,机制byproduct n. 副产品consumption n. 消费,消费量,肺病radiative adj. 辐射的notably adv. 显著地,特别地plutonium n. [化]钚alternate adj. v. 交替,轮流,改变split v. 分裂,分离n. 裂开,裂口sequence n. 次序,顺序,序列事物illustrate vt. 举例说明,图解vi. 举例approach n. 接近,走进,方法,步骤,途径,vt.接近excess n. 过度,剩于,超额adj. 过度的,额外的distortion n. 扭曲,变形,曲解,失真dumbbell n. 哑铃蠢人,笨蛋oscillate v. 振荡analogous adj. 类似的,相似的,可比拟的dominance n. 优势,统治bear n. 熊v. 负担,忍受,带给,具有around adv. 周围,大约prep. 在...周围resultant adj. 作为结果而发生的,合成的recoverable adj. 可重获的takes p1ace 发生prompt adj. 敏捷的,迅速的,即时的prompt neutrons 瞬发中子give rise to v. 引起,使发生asterisk n. 星号signifies vt. 表示,意味vi. 有重要性ground state 基态on the ground that 基于，由于undergo vt. 经历,遭受,忍受terminology n. 术语学fissile adj. 易分裂的,易裂的,裂变的fissionable n. 可裂变物质adj. 可引起核分裂的peed v. 增殖(使)繁殖,教养n. 品种californium n. 锎explanation n. 解释,解说,说明,辩解trigger vt. 引发,引起,触发n. 板机emerge vi. 显现,浮现,暴露,形成sustaining adj. 支持的,持续的emerge from 自...出现so-called adj. 所谓的,号称的inherent adj. 固有的,内在的,与生俱来的controllability 可控性krypton n. [化]氪barium n. 钡ordinate n. [数]纵线,纵座标deficiency n. 缺乏,不足prominent adj. 卓越的,显著的,突出的emanations n. 散发,发出extract n. 榨出物vt. 拔出,榨取,摘录neodymium n. [化]钕Nd moderator n. 缓和剂succession n. 连续,继承,轮栽,连续性extraneous adj. 无关系的,外来的accounted for v. 说明,考虑,解决,得分ultimately adv. 最后,终于,根本,基本上fuse n. 保险丝,熔丝v. 熔合due n. 应得物adj. 应得的comments 注解,注释in effect adv. 有效terrestrial adj. 陆地hydrogen bomb 氢弹proceed vi. 进行,继续下去,发生utilize vt. 利用as yet adv. 至今promising adj. 有希望的,有前途的abpeviate v. 缩写,简化,简写成inexhaustible adj. 无穷无尽的deuteron n. 氘核designate vt. 指明,任命,指派likelihood 可能,可能性(possibility)deuterium [化]氘(氢的放射性同位素)tritium [化]氚(氢的放射性同位素)composite 合成的,复合的合成物feasible adj. 可行的,切实可行的ingredients n. 成分,因素other than adv. 不同于,除了go into v. 进入,加入,探究,变得heat up v. 加热plasma 血浆,乳浆等离子体(区)constraint n. 约束,强制,局促prematurely adv. 过早地,早熟地elevated 提高的,严肃的,欢欣的rarefied adj. 纯净的,稀薄的ignition n. 点火,点燃Chapter8-wordsaccelerator n. 加速者,加速器ever-increasing 连续增长的capacitor n. (=capacitator)电容器experience n. vt. 经验,体验,经历perpendicularly adv. 垂直地,直立地gyration n. 旋回,回转,旋转,[动]螺层helix n. 螺旋,螺旋状物,[解剖]耳轮in parallel 并联in series 串联rectifier n. 纠正者,校正者,整流器transformer n. [电]变压器,使变化的人insulate vt. 使绝缘,隔离rather than 胜于electrodes n. 电极gap 缺口,裂口,间隙,缝隙,差距,隔阂linear accelerator 直线加速器cyclotron n. 回旋加速器poles n. 柱,杆,极,磁极,电极electromagnet n. 电磁石hollow n. 洞,山谷adj. 空腹的,凹的dee n. D 字,D 字形马具polarity n. 极性impetus n. 推动力,促进synchronize v. 同步spiral adj. 螺旋形的n. 螺旋v. 盘旋outermost adj. 最外面的,最远的betatron n. 电子感应加速器doughnut n. 油炸圈饼n. 圆环图tangential adj. 切线的synchrotron n. 同步加速器circumference n. 圆周,周围superpose vt. 放在上面,重叠booster n 支持者,后援者,调压器spallation n. 分裂,蜕变relativistic adj. 相对论的。

1.1工程热力学基础Thermodynamics is a science in which the storage, transformation, and transfer of energy are studied. Energy is stored as internal energy (associated with temperature), kinetic energy (due to motion), potential energy (due to elevation) and chemical energy (due to chemical composition); it is transformed from one of these forms to another; and it is transferred across a boundary as either heat or work.热力学是一门研究能量储存、转换及传递的科学。

能量以内能（与温度有关）、动能（由物体运动引起）、势能（由高度引起）和化学能（与化学组成相关）的形式储存。

不同形式的能量可以相互转化，而且能量在边界上可以以热和功的形式进行传递。

In thermodynamics, we will derive equations that relate the transformations and transfers of energy to properties such as temperature, pressure, and density. Substances and their properties, thus, become very important in thermodynamics. Many of our equations will be based on experimental observations that have been organized into mathematical statements or laws; the first and second laws of thermodynamics are the most widely used.在热力学中，我们将推导有关能量转化和传递与物性参数，如温度、压强及密度等关系间的方程。

Enhancement of CO2Adsorption and CO2/N2Selectivity on ZIF-8via Postsynthetic ModificationZhijuan ZhangSchool of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou,510640,P.R.ChinaDept.of Chemistry and Chemical Biology,Rutgers University,Piscataway,New Jersey,08854Shikai Xian,Qibin Xia,Haihui Wang,and Zhong LiSchool of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou,510640,P.R.ChinaJing LiDept.of Chemistry and Chemical Biology,Rutgers University,Piscataway,New Jersey,08854DOI10.1002/aic.13970Published online January11,2013in Wiley Online Library()Imidazolate framework ZIF-8is modified via postsynthetic method using etheylenediamine to improve its adsorption per-formance toward CO2.Results show that the BET surface area of the modified ZIF-8(ED-ZIF-8)increases by39%,and its adsorption capacity of CO2per surface area is almost two times of that on ZIF-8at298K and25bar.H2O uptake on the ED-ZIF-8become obviously lower compared to the ZIF-8.The ED-ZIF-8selectivity for CO2/N2adsorption gets significantly improved,and is up to23and13.9separately at0.1and0.5bar,being almost twice of those of the ZIF-8. The isosteric heat of CO2adsorption(Q st)on the ED-ZIF-8becomes higher,while Q st of N2gets slightly lower com-pared to those on the ZIF-8Furthermore,it suggests that the postsynthetic modification of the ZIF-8not only improves its adsorption capacity of CO2greatly,but also enhances its adsorption selectivity for CO2/N2/H2O significantly. V C2013American Institute of Chemical Engineers AIChE J,59:2195–2206,2013Keywords:ZIF-8,modification,adsorption/gas,isosteric heat of adsorption,selectivityIntroductionCO2has often been cited as the primary anthropogenicgreenhouse gas(GHG)as well as the leading culprit inglobal climate change.The development of a viable carboncapture and sequestration technology(CCS),is therefore,ascientific challenge of the highest order.1–4Currently,a vari-ety of methods,such as membrane separation,chemicalabsorption with solvents,and adsorption with solid adsorb-ents,have been proposed to sequester CO2from thefluegases of power plant.Thereinto,the adsorption is consideredto be one of the most promising technologies for capturingCO2fromflue gases because of their easy control,low oper-ating and capital costs,and superior energy efficiency.5–7Many adsorbents have been investigated for CO2adsorptionincluding activated carbons,zeolites,hydrotalcites and metaloxides.8–14However,although some zeolite materials havebeen claimed to be most adequate for CO2separation fromflue streams,it is difficult to regenerate them without signifi-cant heating which leads to low productivity and greatexpense.15,16Recently,metal-organic frameworks(MOFs)haveattracted great attention and present a promising platform forthe development of next-generation capture materialsbecause of their high capacity for gas adsorption and tunablepore surfaces that can facilitate highly selective binding ofCO2.17–26To optimize a MOF for a particular application,itis important to be able to tailor its pore metrics and function-ality in a straightforward fashion.However,tailoring MOFsmaterials by modifying their textural properties(e.g.,surfacearea and pore volume)and surface chemistry(acid–baseproperties,functional groups)for adsorption application isstill a difficult task.27Many researchers have given insightinto modification of the MOF materials so as to develop newand better adsorbents.Strategies reported include ligandfunctionalization,24,28–39framework interpenetration,22,23introduction of alkali-metal cations,40–42control of poresize32,43–47and incorporation of open metal sites(OMSs).39,48–51However,because of the instability underconditions for the synthesis of MOFs or the competitivereaction with some framework components,it may be diffi-cult for certain functional groups to incorporate into MOFsusing aforementioned strategies.Another strategy for gener-ating desired functionalities in MOFs is the postsynthesis Additional Supporting Information may be found in the online version of thisarticle.Correspondence concerning this article should be addressed to Z.Li atcezhli@.V C2013American Institute of Chemical EngineersAIChE Journal2195June2013Vol.59,No.6modification of preconstructed,robust precursor MOFs.52–55 For example,An et al.33demonstrated that postsynthetic exchange of extra-framework cations within anionic bio-MOF-156can be used as a means to systematically modify its pore dimensions and metrics.Farha et al.57synthesized a series of cavity modified MOFs by replacing coordinated sol-vents with several different pyridine ligands.They found that a p-(CF3)NC5H4-modified MOF showed considerable improvements in the CO2/N2selectivities compared to the parent framework.46Long and his coworkers58previously reported the grafting of ethylenediamine(en)within a water-stable MOF H3[(Cu4Cl)3(BTTri)8](CuBTTri),and found that the en modified sample had more greater attraction of CO2 at low pressures and the CO2/N2selectivity also increased over the entire pressure range measured.More recently, Long and coworkers59incorporated the N,N0-dimethylethyle-nediamine(mmen)into the CuBTTri MOF,and showed that the CO2uptake was drastically enhanced.Zhang et al.60 reported that after ZIF-8was modified by ammonia impreg-nation,the surface basicity was greatly increased and there-fore the CO2uptake was enhanced.Park et al.61reported a postsynthetic reversible incorporation of organic linkers3,6-di(4-pyridyl)-1,2,4,5-tetrazine(bpta)into SNU-30 [Zn2(TCPBDA)(H2O)2]Á30DMFÁ6H2O through single-crystal-to-single-crystal transformations,and found that the desol-vated SNU-310exhibited enhanced selective adsorption of CO2over N2.Xiang et al.62incorporated the CNTs into HKUST-1,and then modified it with Li1.The results showed that the hybrid Li@CNT@[Cu3(btc)2],which is formed by the combination of Li doping and CNT incorpora-tion,having an enhancement of CO2uptakes by about 305%.However,to this date,no work has been reported out on the postsynthetic modification of ZIF-8to enhance its functionality.In this work,the postsynthetic modification of the ZIF-8is proposed to prepare a novel adsorbent with higher CO2 adsorption capacity and CO2/N2selectivity.The postsyn-thetic modification of the ZIF-8crystals would be carried out by using ethylenediamine treatment.Then the surface groups of the modified ZIF-8samples(ED-ZIF-8)would be characterized.Single-component isotherms of CO2and N2 on the modified ZIF-8samples would be measured sepa-rately.Furthermore,the CO2/N2selectivity is estimated by using IAST on the basis of single-component isotherms of CO2and N2.The influence of the textural structures and sur-face chemistry of the original and modified ZIF-8samples on their adsorption capacities for CO2and selectivity of CO2/N2would be discussed and reported here.This informa-tion will be valuable for selecting appropriate adsorbents for CO2capture process.Methods and MaterialsMaterials and instrumentsZinc nitrate hexahydrate(Zn(NO3)2Á6H2O,98%,extra pu-rity)and2-methylimidazole(H A MeIM)(99%purity)were purchased from J&K Chemicals.N,N A Dimethylacetamide (DMF)was purchased from Qiangshen Chemicals Co.,Ltd. of Jiangshu(Jiangshu,China),and it was further purified by 4A molecular sieve to eliminate the water.Maganetic suspension balance RUBOTHERM was sup-plied by Germany.Its precision was0.000001g.ASAP 2010sorptometer was supplied by Micromeritics Co., Norcross,GA,USA.AdsorbentsSynthesis of ZIF-8was performed following the reported procedures63with a few modifications.First,a solid mixture of zinc nitrate hexahydrate Zn(NO3)2Á6H2O(0.956g, 3.2 mmol)and2-methylimidazole(H A MeIM)(0.24g, 3.4 mmol)was dissolved in70mL of DMF solvent.The mixture was quickly transferred to a100mL autoclave and sealed. Second,the autoclave was heated at a rate of5K/min to 413K in a programmable oven and held at this temperature for24h under autogenous pressure by solvothermal synthe-sis,followed by cooling at a rate of0.3K/min to room tem-perature.Third,after removal of mother liquor from the mix-ture,chloroform(40mL)was added to the autoclave.The as-synthesized ZIF-8crystals were then isolated byfiltration. Colorless polyhedral crystals were collected from the upper layer,washed with DMF(10mL33),and dried at383K overnight.To further remove the guest species from the framework and prepare the evacuated form of ZIF-8crystals for modifi-cation and gas-sorption analysis,the as-synthesized ZIF sam-ples were immersed in methanol at ambient temperature for 48h,and evacuated at ambient temperature for5h,and sub-sequently at an elevated temperature673K for2h. Postsynthetic modification of adsorbentsThe as-synthesized ZIF-8crystals(labeled as ZIF-8)were dried at383K for24h for postsynthetic modification.The subsequent treatment applied to the modification of ZIF-8crystals consists of the following steps:The modified ZIF-8sample(labeled as ED-ZIF-8)was synthesized using ethylenediamine as a linker.In a typical procedure,the ZIF-8sample was added to30%ethylenediamine solution and then the mixture was placed in a stainless high-pressure autoclave.The autoclave was heated in an oven at416K for 1h and then381K for6h.The light yellow product wasfil-tered and washed with deionized water.Finally,the sample was dried at383K overnight.Characterization of adsorbentsThe specific surface area and pore volume of original ZIF-8and modified ZIF-8crystals were measured on a Micrometrics gas adsorption analyzer ASAP2010instrument equipped with commercial software for calculation and analysis.Powder X-ray diffraction data were collected using a D8 advance h-2h diffractometer(Bruker)in reflectance Bragg-Brentano geometry employing Cu K a line focused radiation with40kV voltages and40mA current.The X-ray scanning speed was set at2 /min and a step size of0.02 in2h.A Jade5XRD pattern processing software(MDI,Inc.,Liver-more,CA)was used to analyze the XRD data collected on the ZIF-8samples.The surface organic molecules were analyzed by taking FTIR spectra on a Bruker550FTIR instrument equipped with a diffuse reflectance accessory that included a reaction cell.Data acquisition was performed automatically using an interfaced computer and a standard software package.The samples were dried in vacuo at423K prior to mixing with KBr powder.The samples were run in ratio mode allowing for subtraction of a pure KBr baseline.The sample chamber2196DOI10.1002/aic Published on behalf of the AIChE June2013Vol.59,No.6AIChEJournalwas kept purged with nitrogen during the entire experiment.The spectrometer collected 64spectra in the range of 400–4,000cm 21,with a resolution of 4cm 21.CO 2and N 2adsorption measurementsThe CO 2and N 2adsorption-desorption isotherms at 298K,308K,318K,and 328K were obtained on a RUBO-THERM magnetic suspension balance.The initial activa-tion of the modified sample was carried out at 423K for 12h in a vacuum environment.He (ultra-high purity,U-sung)was used as a purge gas in this study.The adsorp-tion processes were carried out using high purity CO 2and N 2(99.999%)gas.A feed flow rate of 60mL/min of CO 2,40mL/min of N 2and 30mL/min of He,respec-tively,were controlled with the mass flow controllers (MFC)to the sample chamber.Both adsorption and de-sorption experiments were conducted at the same tempera-ture.The temperature of the sorption chamber can be adjusted and maintained constant by an internal tempera-ture sensor.However,the pressure can be changed step-wise through the gas flow rate.Typically,there are four steps for finishing determination of an isotherm of CO 2or N 2by using Rubotherm magnetic suspension balance.These detail steps are shown by the operation manual of Rubotherm maganetic suspension balance.H 2O adsorption measurementsThe water adsorption measurements were conducted on a computer-controlled DuPont Model 990TGA.The partial pressure of water was varied by changing the blending ratios of water-saturated nitrogen and pure nitrogen gas streams.Before measurement,the modified ZIF-8samples were acti-vated at 423K for 6h.Results and DiscussionStructure and pore characterizationFigure 1exhibits the adsorption-desorption isotherms of N 2at 77K on the two samples ZIF-8and ED-ZIF-8.It can be seen that both samples show type-I behavior,indicating they are microporous in nature.Table 1lists structure param-eters of the two samples.These data indicate that the BET surface area and micropore volume of the ED-ZIF-8sample are significantly higher than those of the original ZIF-8sam-ple,with an increase of $39%and 35.6%,respectively.Yaghi and his coworkers reported a pore volume of 0.66cm 3/g for ZIF-8from the single crystal structure.For the ZIF-8sample,the total pore volume is calculated to be 0.54cm 3/g,because part of the pores might be blocked.However,after the postsynthetic modification,the blocked pores were reopened,and at meanwhile,some new pores were formed.64,65Thus,the total pore volume of the ED-ZIF-8sample is greatly improved.Figure 2shows the powder X-ray diffraction (PXRD)pat-tern of the modified ZIF-8sample.It can be seen that the main peaks of the modified ZIF-8sample are very clear,and similar to those of the original ZIF-8sample,indicating that the integrity of the modified ZIF-8sample maintains well af-ter the postsynthetic modification.However,for a deep look-ing,it can be found that the major peaks of ED-ZIF-8all shifted to the left side (low-angle area)a little bit,which means after modification,the lattice distance increased.In order to obtain information concerning changes in the surface groups,FTIR experiments were carried out to char-acterize the samples.Figure 3a shows the FTIR spectra of the original ZIF-8and the ED-ZIF-8sample.It is noticed that the spectra for the two samples show high similarities,and the main peaks of both ZIF-8samples match well with the published FTIR spectra for the ZIF-8.However,someTable 1.Porous Structure Parameters of the Modified ZIF-8CrystalsSample BET surface area (m 2.g 21)Langmuir surface area (m 2.g 21)Micropore volume(cm 3.g 21)Total pore volume (cm 3.g 21)Micropore diameter (nm)Mesopore diameter (nm)ZIF-8102513520.450.540.352 4.43ED-ZIF-8142818970.610.750.5444.53Figure 1.N 2adsorption-desorption isotherms of ZIF-8and ED-ZIF-8samples.[Color figure can be viewed in the online issue,which is available at .]Figure2.PXRD patterns of ZIF-8and ED-ZIF-8samples.[Color figure can be viewed in the online issue,which is available at .]AIChE Journal June 2013Vol.59,No.6Published on behalf of the AIChE DOI 10.1002/aic2197differences are also observed.For example,the spectrum of the ED-ZIF-8sample is different from that of the ZIF-8sam-ple in that (1)as shown in Figure 3b there is a new peak at 3381cm 21which is assigned to N A H group appeared on the spectrum of the ED-ZIF-8sample,suggesting some N A H groups have been introduced on the surfaces of the sample ED-ZIF-8,and (2)a peak at 3626cm 21assigned to O A H of the adsorbed H 2O is present in the spectrum of the ZIF-8sample,which is absent in the spectrum of the ED-ZIF-8sample,as shown in Figure 3b.CO 2and N 2adsorption isothermsFor comparison,Figure 4shows the isotherms of CO 2on the ZIF-8and ED-ZIF-8samples.It is visible that the amount adsorbed of CO 2increases as temperature decreases.This suggests that the adsorption of CO 2is mainly physical adsorption.More importantly,it is found that the ED-ZIF-8sample had higher CO 2adsorption capacities compared to the ZIF-8sample,indicating that the adsorption capacities of the modified ZIF-8toward CO 2are greatly improved,nearly being twice as much as the ZIF-8.One of the reasons is that the surface area (BET)of the ED-ZIF-8increases by 39%,as indicated in Table 1.The other reason is that adsorptioncapacity per unit surface area of the ED-ZIF-8for CO 2increases due to an introduction of N A H groups by postsyn-thetic modification.To further understand that,Figure 4a and 4b are separately transferred into Figure 5a and 5b in which the equilibrium uptakes of CO 2based on unit surface area (BET)of the two samples are plotted as a function of CO paring Figure 5b and Figure 5a shows that the CO 2uptake per surface area (BET)of the ED-ZIF-8is obvi-ously higher than that of the ZIF-8,which is mainly ascribed to the introduction of N A H groups,as shown in Figure 3.Figure 6a and 6b show the N 2adsorption isotherms on the two samples.It is visible that the N 2uptakes on the modified ZIF-8samples are slightly higher than that on the ZIF-8due to its larger surface area and pore volume after modification.However,after Figure 6a and 6b are converted into Figure 7a and 7b in which the equilibrium uptakes of N 2based on unit surface area of the two samples are plotted as a function of pressure,it is found from Figure 7that the equilibrium uptakes of N 2per surface area of the ED-ZIF-8are slightly lower than that of the ZIF-8,which means that ED-ZIF-8sample has less affinity toward N 2than ZIF-8sample.This will be helpful to enhance the adsorption selectivity for CO 2/N 2.Figure 3.a.FTIR spectra of the modified ZIF-8crystalsbetween 4,000–400cm 21;b.FTIR spectra of the modified ZIF-8crystals between 4000–2,400cm 21.[Color figure can be viewed in the online issue,which is available at .]Figure 4.a.Isotherms of CO 2on the ZIF-8sample withdifferent temperatures; b.isotherms of CO 2on the ED-ZIF-8sample with different temperatures.[Color figure can be viewed in the online issue,which is available at .]2198DOI 10.1002/aicPublished on behalf of the AIChE June 2013Vol.59,No.6AIChEJournalMultiple cycles of CO 2adsorption-desorption on the ED-ZIF-8To evaluate the regeneration performance of the modified sample or the reversibility of CO 2adsorption on the modi-fied sample,the experiments of multiple cycles of CO 2adsorption-desorption on the ED-ZIF-8were performed in the Rubotherm system at 298K.For adsorption process,the adsorption pressure were targeted for 25bar;while for de-sorption process the system pressure was targeted for 1mbar,and then the desorption system was quickly depressur-ized by using vacuum pumping.Figure 8shows the variation curve of the amounts adsorbed of CO 2on the ED-ZIF-8dur-ing four consecutive cycles of CO 2adsorption-desorption experiments at 298K.It was visible clearly that during the desorption,the amounts adsorbed of CO 2on the ED-ZIF-8sample decreased sharply with time,and then reached a very low content,about 2.21wt %of residual CO 2which was present on the sample after desorption at 1mbar.The effi-ciency of CO 2desorption was nearly up to 98%over the entire four circles.It indicated further that CO 2adsorption was reversible with very little accumulation of irreversible bound CO 2on the ED-ZIF-8framework.In addition,it wasalso observed from Figure 8that the curves representing the cycles of CO 2adsorption-desorption experiments were very similar,suggesting that adsorption and desorption properties of the sample ED-ZIF-8for CO 2were stable or repeatable.It also proved that the pressure swing was effective in strip-ping adsorbed CO 2from the ED-ZIF-8.H 2O adsorption isothermsFigure 9shows the water isotherms on the modified ZIF-8samples at 298K.The water uptake on the ED-ZIF-8sample is less than that on the ZIF-8sample,indicating that the sur-face of the modified sample became more hydrophobic com-pared to the ZIF-8sample.It also means that the interaction of the water molecule with the modified sample became weaker as compared to that with the ZIF-8.Ideal adsorbed solution theory (IAST)selectivity of CO 2/N 2The ideal adsorbed solution theory (IAST)developed by Myers and Praunitz 66provides an effective method to predict the adsorption selectivity and the adsorption equilibrium of gas mixtures from the isotherms of the pure components.Figure 5.a.Isotherms of CO 2on the ZIF-8samplebased on unit surface area;b.isotherms of CO 2on the ED-ZIF-8sample based on unit surface area.[Color figure can be viewed in the online issue,which is available at .]Figure 6.a.Isotherms of N 2on the ZIF-8sample atdifferent temperatures;b.isotherms of N 2on the ED-ZIF-8sample at different temperatures.[Color figure can be viewed in the online issue,which is available at .]AIChE JournalJune 2013Vol.59,No.6Published on behalf of the AIChE DOI 10.1002/aic2199Previous work reported that the IAST can accurately predict gas mixture adsorption in a number of zeolites and MOF materials.10,48,67–70The IAST assumes that the adsorbed mixture is an ideal solution at constant spreading pressure and temperature,where all the components in the mixture conform to the rule analogous to Raoult’s law,and the chemical potential of the adsorbed solution is considered equal to that of the gas phase at equilibrium.From the IAST,the spreading pressure p is given byp 0i ðp 0i Þ5RT A ðp 0iqd ln p (1)p Ã5p A 5ðp 0i 0q i dp (2)Where A is the specific surface area of the adsorbent,p andp *are the spreading pressure and the reduced spreading pres-sure,separately.p 0i is the gas pressure of component i corre-sponding to the spreading pressure p of the gas mixture.At a constant temperature,the spreading pressure of single component is the samep Ã15p Ã25…5p Ãn 5p(3)For binary adsorption of component 1and 2,the IASTrequiresy 1p t 5x 1p 1ð12y 1Þp t 5ð12x 1Þp 2(4)Where y 1and x 1denote the molar fractions of component 1in the gas phase and in the adsorbed phase,respectively.p t is the total gas pressure,p 1and p 2are the pressures of com-ponent 1and 2at the same spreading pressure as that of the mixture,respectively.Adsorption selectivity in a binary mixture of component 1and 2is defined asS 125x 1x 2 y 2y 1 (5)For the application of IAST to predict adsorption separa-tion selectivity,the following two conditions are necessary:good quality adsorption data of each single component;and excellent curve fitting model for such data.48,71,72In order to perform the integrations of Eqs.(1)and (2)required by IAST,the single-component isotherms should be fitted by a proper isotherm model.In practice,several meth-ods are available.In this work,it is found that the dual-site Langmuir-Freundlich (DSLF)equation can be successful to fit this set of adsorption data.The dual-site Langmuir-Freundlich model can be expressed as followsq 5q m ;13b 1p 1=n 111b 1p 11q m ;23b 2p 1=n 211b 2p 2(6)Where p is the pressure of the bulk gas at equilibrium with the adsorbed phase (kPa),q m,1,q m,2are the saturation capaci-ties of sites 1and 2(mmol/g),b 1and b 2are the affinity coefficients of sites 1and 2(1/kPa),and n 1and n 2are the deviations from an ideal homogeneous surface.Figure 10shows a comparison of the model fits and the isotherm data.It is visible that the DSLF model can be applied favorably for fitting experimental data of CO 2and N 2adsorption.Table 2presents the fitting parameters ofFigure 7.a.Isotherms of N 2on the ZIF-8sample basedon unit surface area;b.isotherms of N 2on the ED-ZIF-8sample based on unit surface area.[Color figure can be viewed in the online issue,which is available at .]Figure 8.Recycle runs of CO 2adsorption-desorptionon the ED-ZIF-8at 298K and 25bar for adsorption and 1mbar for desorption.[Color figure can be viewed in the online issue,which is available at .]2200DOI 10.1002/aicPublished on behalf of the AIChE June 2013Vol.59,No.6AIChEJournalDSLF equation as well as the correlation coefficients (R 2).Examination of the data shows that this DSLF model is able to fit the adsorption data well since the correlation coeffi-cients R 2are up to 0.9997.In this work,the equilibrium adsorption data of single component CO 2as well as N 2are available,and the DSLF model can fit the experimental isotherms of CO 2and N 2adsorption very well.Therefore,the DSLF model can be combined with the ideal adsorbed solution theory (IAST)to predict the mixture adsorption isotherms and calculate the selectivities of the two samples for CO 2/N 2adsorption.Figure 11a and 11b present,respectively,the adsorption isotherms predicted by IAST for equimolar mixtures of CO 2/N 2in the samples ZIF-8and ED-ZIF-8as a function of total bulk pressure.It can be seen that CO 2is preferentially adsorbed over N 2on the two samples because of stronger interactions between CO 2and the ZIF-8sample,and the amount adsorbed of N 2is much lower in the mixtures than that in single-component adsorption because of competition adsorption from CO 2,which adsorbs more strongly.Figure 12shows the IAST-predicted selectivities of the two samples for equimolar CO 2and N 2mixtures at 298K as a function of total bulk pressure.It can be seen that the adsorption selectivity of the two samples for CO 2/N 2dropped with an increase in the pressure.More importantly,Figure 9.H 2O adsorption isotherms on the modifiedZIF-8samples at 298K.[Color figure can be viewed in the online issue,which is available at .]Table 2.The Fitting Parameters of the Dual-site Langmuir-Freundlich Equations for the Pure Isotherms of CO 2and N 2at 298KZIF-8ED-ZIF-8CO 2N 2CO 2N 2R 20.99970.99990.99970.9999q m,1(mmol/g)27.2527.8748.8828.32q m,2(mmol/g) 2.122 1.919 4.672 1.847b 1(atm 21)0.015330.0011700.012590.001388b 2(atm 21)0.0068950.026090.029480.02504n 1 1.6000.7875 1.4040.7704n 20.32440.96340.44300.8671Figure 10.DSLF fitting of the CO 2and N 2isotherms onZIF-8and ED-ZIF-8at 298K.[Color figure can be viewed in the online issue,which is available at .]Figure11.a.The IAST -predicted isotherm forequimolar CO 2/N 2mixtures of the ZIF-8sample at 298K as a function of total bulk pressure; b.the IAST -predicted isotherm for equimolar CO 2/N 2mixtures of the ED-ZIF-8sample at 298K as a function of total bulk pressure.[Color figure can be viewed in the online issue,which is available at .]AIChE Journal June 2013Vol.59,No.6Published on behalf of the AIChE DOI 10.1002/aic2201the adsorption selectivity of CO 2/N 2on the sample ED-ZIF-8is always higher than that on the sample ZIF-8,especially in the low-pressure region.For example,at 0.1and 0.5bar,the selectivity of the sample ED-ZIF-8for CO 2/N 2were up to 23and 13.9separately,which is almost twice of those of the sample ZIF-8.Figure 13a and 13b show,respectively,the IAST-pre-dicted selectivities of the samples ZIF-8and ED-ZIF-8for CO 2/N 2at different mixture compositions and different pres-sures.It is noticed that the selectivity increases rapidly as the gas-phase mole fraction of N 2approaches unity.For example,at yN 250.9,a typical feed composition of flue gas,high selectivities are obtained.Even at yN 250.5,the selectivity of the ED-ZIF-8for CO 2/N 2is in the range of 6–24,much higher than those on the ZIF-8sample and many other MOF samples such as ZIF-7030,ZIF-6830and MOF-508b.73This property is very important since some separa-tion processes could be operated at low pressures,such as vacuum swing adsorption (VSA),which could be extremely efficient by using the sample ED-ZIF-8because its selectiv-ity increases dramatically with decreasing pressure.Ideal adsorbed solution theory (IAST)selectivity of CO 2/N 2/H 2OThe major challenge of CO 2capture from power plant flue gas wastes is the separation of CO 2/N 2.In addition,competition adsorption of water molecule must be taken into account,because these flue gas wastes are usually saturated with certain amount of water (5–7%by volume)for the industrial postcombustion processes.Thus,for real industrial use of adsorbents,the effect of water on CO 2/N 2selectivity is another crucial factor that needs to be considered and evaluated.Here,the IAST was adopted to evaluate the ter-nary mixture CO 2/N 2/H 2O adsorption on the modified ZIF-8samples.First,the experimental isotherms of water on the modified ZIF-8samples at 298K were fitted using the DSLF model.Table 3presents the fitting parameters of DSLF equation as well as the correlation coefficients.It can be seen that theDSLF model fits the H 2O adsorption on both samples very well.Second,the DSLF model was combined with the ideal adsorbed solution theory (IAST)to predict the mixture adsorption isotherms,and then calculate the selectivities of the two samples for CO 2/N 2adsorption.Figure 14shows the predicted isotherms of ternary mix-ture CO 2/N 2/H 2O on the modified ZIF-8samples at 298K.It can be observed that in comparison with the ZIF-8,after modification,the CO 2adsorption capacity of the ED-ZIF-8in the ternary mixture obviously increased,and its N 2adsorption capacity somewhat increased,which made CO 2/N 2adsorption selectivity of the ED-ZIF-8increase.More importantly,its water adsorption capacity in the ternary mix-ture became lower compared to the ZIF-8,and it was also lower than the single component water uptake.It means the competition adsorption of H 2O in the ternary mixture was weakened on the surfaces of the ED-ZIF-8sample.Figure 12.The IAST -predicted selectivity for equimolarCO 2and N 2at 298K as a function of total bulk pressure.[Color figure can be viewed in the online issue,which is available at .]Figure 13.a.The IAST predicted selectivities atdifferent mixture compositions and different pressures for the ZIF-8sample at 298K;b.the IAST predicted selectivities at different mixture compositions and different pressures for the ED-ZIF-8sample at 298K.[Color figure can be viewed in the online issue,which is available at .]2202DOI 10.1002/aicPublished on behalf of the AIChE June 2013Vol.59,No.6AIChEJournal。

第三章理想⽓体的性质与热⼒过程第三章理想⽓体的性质和理想⽓体的热⼒过程英⽂习题1. Mass of air in a roomDetermine the mass of the air in a room whose dimensions are 4 m×5 m×6 m at 100 kPa and 25℃2. State equation of an ideal gasA cylinder with a capacity of 2.0 m 3contained oxygen gas at a pressure of 500 kPa and 25℃ initially. Then a leak developed and was not discovered until the pressure dropped to 300 kPa while the temperature stayed the same. Assuming ideal-gas behavior, determine how much oxygen had leaked out of the cylinder by the time the leak was discovered.3. Two tanks are connected by a valve. One tank contains 2 kg of carbon monoxide gas at 77oC and0.7 bar. The other tank holds 8 kg of the same gas at 27oC and 1.2 bar. The valve is opened and the gases are allowed to mix while receiving energy by heat transfer from the surrounding. The final ideal gas equilibrium temperature is 42℃ Using the model, determine (a) the final equilibrium pressure, in bar, and (b) the heat transfer for the process,in kJ.4. Electric heating of air in a houseThe electric heating systems used in many houses c o nsist of a simple duct with resistance wires. Air is heated as it flows over resistance wires. Consider a 15-kW electric system. Air enters the heating section at 100 kPa and 17oC with a volume flow rate of 150 m 3/min. If heat is lost from the air in the duct to the surroundings at a rate of 200 W, determine the exit temperature of air.C P =1.005 kJ/(kg. K).5. Evaluation of the Δu of an ideal gasAir at 300 K and 200 kPa is heated at constant pressure to 600 K. Determine the change in internal energy of air per unit mass, using (a) data from the air table, (b) the functional form of the specific heat, and (c) the average specific heat value.6. Properties of an ideal gasA gas has a density of 1.875 kg/m 3at a pressure of 1 bar and with a temperature of 15oC. A mass of 0.9 kg of the gas requires a heat transfer of 175 kJ to raise its temperature from 15oC to 250oC while the pressure of the gas remains constant. Determine (1) the characteristic gas constant of the gas, (2) the specific heat capacity of the gas at constant pressure, (3) the specific heat capacity of the gas at constant volume, (4) the change of internal energy, (5) the work transfer.7. Freezing of chicken in a boxCarbon2kg, 77oCarbon 8kg, 27oMonoxide C 0.7bar Monoxide C 1.2bar valve Tank 1Tank 2FIGURE 3-1FIGURE 3-2FIGURE 3-3A supply of 50 kg of chicken at 6℃ contained in a box is to be frozen to -18℃ in a freezer. Determine the amount of heat that needs to be removed. The latent heat of the chicken is 247 kJ/kg, and its specific heat is 3.32 kJ/kg.℃ above freezing and 1.77 kJ/kg.℃ below freezing. The container box is 1.5 kg, and the specific heat of the box material is 1.4 kJ/kg.℃. Also, the freezing temperature of chicken is -2.8℃.8. Closed- system energy balanceA rigid tank which acts as a perfect heat insulator and which has a negligible heat capacity is divided into two unequal partsA andB by a partition. Different amounts of the same ideal gas are contained in the two parts of the tank. The initial conditions of temperature T, pressure p, and total volume V are known for both parts of the tank. Find expressions for the equilibrium temperature T and pressure P reached after removal of the partition. Calculate the entropy change for A and B and the totalentropy change of the tank. Assume that Cv,m is constant,9. Thermal processes of an ideal gasAn air receiver has a capacity of 0.85 m 3and contains air at a temperature of 15℃ and a pressure of 275 kN/m 3. An additional mass of 1.7 kg is pumped into the receiver. It is then left until the temperature becomes 15℃ once again. Determine (1) the new pressure of the air in the receiver, (2) the specific enthalpy of the air at 15℃ if it is assumed that the specific enthalpy of the air is zero at 0℃. Take cp=1.005 kJ/kg.K, cc=0.715 kJ/kg.K.10. Air is compressed steadily by a reversible compressor from an inlet state of 100KPa and 300K toan exit pressure of 900 kPa. Determine the compressor work per unit mass for isentropic compression with k=1.4, (1) isentropic compression with k=1.4, (2) polytropic compression with n=1.3, (3) isothermal compression, and (4) ideal two-stage compression with intercooling with a polytropic exponent of 1.3.11. A rigid cylinder contains a “floating” piston, free to mo ve within the cylinder without friction. Initially,it divided the cylinder in half, and on each side of the piston the cylinder holds 1 kg of the same ideal gas at 20oC, and 0.2 MPa . An electrical resistance heater is installed on side A of the cylinder, and it is energized slowly to P A2=P B2=0.4 MPa. If the tank and the piston are perfect heat insulators and are of negligible heat capacity, cv=0.72 kJ/(kg·K). Calculate （1）the final temperatures, volumes of A,B sides, （2）the amount of heat added to the system by the resistor. (3）the entropy changes of A,B sides, （4）the total entropy change of the cylinder.⼯程热⼒学与传热学第三章理想⽓体的性质和热⼒过程习题1 理想⽓体的c p 和c V 之差及c p 和c V 之⽐是否在任何温度下都等于⼀个常数？习题0.20.1MPa 300K 0.01m 3AMPa 300K 0.01m 3BFIGURE 3-42如果⽐热容是温度t 的单调增函数，当t 2 >t 1时平均⽐热容2121,,00t t t t c c c 中哪⼀个最⼤？哪⼀个最⼩？ 3如果某种⼯质的状态⽅程式遵循T R pv g ，这种物质的⽐热容⼀定是常数吗？这种物质的⽐热容仅是温度的函数吗？ 4在p-v 图上画出定⽐热容理想⽓体的可逆定容加热过程，可逆定压加热过程，可逆定温加热过程和可逆绝热膨胀过程。

PRESSURE EFFECT AND SPECIFIC HEAT OF RB a2Cu3O x AT DISTINCT CHARGE CARRIER CONCENTRATIONS: POSSIBLE INFLUENCE OF STRIPESS. I. SCHLACHTER1,U. TUTSCH1, W. H. FIETZ1, K.-P. WEISS1, H. LEIBROCK1, K. GRUBE1, Th. WOLF1, B. OBST1, P. SCHWEISS2, AND H. WÜHL1,3.Forschungszentrum Karlsruhe, 1ITP and 2IFP, 76021 Karlsruhe, Germany.3Universität Karlsruhe, IEKP, 76128 Karlsruhe, Germany.In YBa2Cu3O x, distinct features are found in the pressure dependence of the transition temperature,d T c/d p, and in ∆C p⋅T c, where ∆C p is the jump in the specific heat at T c: d T c/d p becomes zero when∆C p⋅T c is maximal, whereas d T c/d p has a peak at lower oxygen contents where ∆C p⋅T c vanishes.Substituting Nd for Y and doping with Ca leads to a shift of these specific oxygen contents, since oxygen order and hole doping by Ca influences the hole content n h in the CuO2 planes. Calculating n hfrom the parabolic T c(n h) behavior, the features coalesce for all samples at n h≈ 0.11 and n h≈ 0.175, irrespective of substitution and doping. Hence, this behavior seems to reflect an intrinsic property ofthe CuO2 planes. Analyzing our results we obtain different mechanisms in three doping regions: T c changes in the optimally doped and overdoped region are mainly caused by charge transfer. In theslightly underdoped region an increasing contribution to d T c/d p is obtained when well ordered CuO chain fragments serve as pinning centers for stripes. This behavior is supported by our results on Zndoped NdBa2Cu3O x and is responsible for the well known d T c/d p peak observed in YBa2Cu3O x atx ≈ 6.7. Going to a hole content below n h≈ 0.11 our results point to a crossover from an underdoped superconductor to a doped antiferromagnet, changing completely the physics of these materials.1IntroductionIn the past years a lot of work has been done to investigate the T(n h) phase diagram of cuprate superconductors, where n h denotes the hole concentration in the CuO2 planes. For n h = 0 the cuprates are Mott insulators with long-range antiferromagnetic order. With increasing n h this antiferromagnetic order is destroyed rapidly and superconductivity sets in. The superconducting transition temperature T c grows with n h in the underdoped region up to a maximum transition temperature T c,max at optimum doping n h,opt and then decreases again in the overdoped region.There is growing evidence that some physical peculiarities in the underdoped region and possibly the superconductivity are a result of a spin-charge separation in the CuO2 planes into line-shaped spin- and hole-rich regions. This so-called stripe phase seems to vanish beyond n h,opt where magnetic correlations become negligible. The observed stripes at 1/8 doping (n h = 0.125) in the La214 compound show that stripe mobility has crucial influence on superconductivity [1]. The introduction of Zn in the CuO2 planes, for example, suppresses superconductivity most likely due to the pinning of fluctuating stripes [2].In the RBa2Cu3O x system (R123, R = rare earth element) the whole underdoped, the optimally doped and the slightly overdoped region can be investigated by varying the oxygen content x. With partial substitution of Ca2+ for Y3+ experiments can even be extended to the heavily overdoped region. In contrast to the La214 compounds the R123 system contains also CuO chains serving as a charge reservoir. This allows changes of the hole concentration of a sample via pressure application without changing the chemistry of the sample, because application of pressure leads to charge transfer from the CuO chains to the CuO2 planes due to different length changes of hard and soft bonds [3]. In this workhydrostatic pressure effect d T c/d p and thespecific heat of Ca doped Y123 and Zn dopedNd123 single crystals.2ExperimentalIn order to determine the pressuredependence of T c(p) we performed ac-susceptibility measurements under absolutelyhydrostatic pressure conditions (p≤ 0.6 GPa)with He gas as pressure-transmitting medium.Pressure-induced oxygen-ordering effects [4],leading to the creation of additional holes inthe CuO chains and therefore as well to anincrease of the hole concentration in theCuO2 planes, have been avoided by exposingthe samples to high pressures only at temperatures below 110 K.The specific-heat measurements were performed by a continuous heating technique with samples of about 30 mg. To substract the normal state background from the specific heat we used data from a Nd/Ba substituted sample with a strong depressed superconducting transition. A mean-field type specific-heat jump ∆C p/T c at T c has been obtained, analyzing the superconducting transition with an entropy conserving construction.The Y1−y Ca y Ba2Cu3O x, as well as the NdBa2(Cu1-z Zn z)3O x samples were grown in Y stabilized ZrO2 crucibles. EDX analysis showed that in the Nd123 samples, corrosion of the crucibles during the growth process lead to a small occupation of about 7 at% Y on Nd sites. Since, however, T c and pressure effect of these samples and of Y free Nd123 samples grown in BaZrO3 crucibles show only very small differences compared to T c and pressure effect of pure Y123 (Fig. 1), in the following w e will not distinguish between Nd123 with and without Y impurities. EDX analysis and neutron diffraction studies gave no hints for other impurities or Nd/Ba misoccupations.The oxygen contents x(T, p) of our samples were adjusted by annealing the samples under flowing oxygen, oxygen/argon or oxygen/nitrogen mixtures. For the Y123 and Nd123 samples the appropriate temperature and oxygen partial pressure for a distinct oxygen content were deduced from Refs. [5] and [6]. In Y1−y Ca y Ba2Cu3O x (YCa123) the oxygen content is reduced in comparison to the expected values from Refs. [5] and [6] by approximately y/2 due to the different valence of Y3+ and Ca2+ [7].3Results and DiscussionsFor many cuprate superconductors, including La2−x Sr x CuO4, La2−x Sr x CaCu2O6 and Y1−y Ca y Ba2Cu3O x with various Ca and oxygen contents, T c(n h) follows a universal parabolic behavior [8]. The optimum hole concentration n h,opt≈ 0.16 is common for all these superconductors, whereas the maximal achievable T c depends on the particularsystem.Following this dependence we measured for each sample the T c values at various oxygen contents to obtain T c,max . With these values we determined n h for each single crystal at the particular oxygen content. In Fig. 2,these n h values are plotted versusoxygen content. For the pure Y123 we find at an oxygen content of6.5 < x < 6.65 the well known 60 K plateau which is caused by oxygen ordering. Due to the larger latticeparameters of Nd123, oxygen ordering is diminished. Therefore, the doping efficiency of oxygen is also diminishedand the same n h values require higher oxygen contents than in Y123 [9]. Due to the doping effect of Ca, the Ca doped Y123 samples show much higher hole concentrations than Y123 at the same oxygen content. The missing signature of the 60 K plateau is caused by the decreasing tendency to a well-ordered oxygen sublattice with increasing Ca content.When our results are plotted as a function of the hole content, however, despite the different doping mechanisms, the d T c /d p (n h ) dependence of the different systems look quite similar, as well as the ∆C p ⋅T c (n h ) dependence (Fig. 3). In the underdoped region the pressure effects of the different systems peak at n h ≈ 0.11, where ∆C p ⋅T c vanishes. On the other hand, in the overdoped region the pressure effects of all samples show an almost linear behavior crossing zero at n h ≈ 0.175. Exactly at this doping level, ∆C p ⋅T c , which is a measure of the condensation energy, shows a maximum for all samples (except for Y123,where a further increase is visible because the well ordered CuO chains become superconducting). The maxima in the condensation energies and the zero pressure effectstogether with other experimentalresults in the literature [10] suggest that superconductivity in the slightlyoverdoped region is extremly stable.The almost linear decrease of the hydrostatic pressure effect in theoverdoped region can be understood in terms of pressure-induced charge-transfer [11] from the CuO chains to the CuO 2 planes, which is mainly caused by pressure along the c -axis direction. For pressure along the a -and b -axis direction pressure-induced charge-transfer can beneglected [12]. According to theparabolic T c (n h ) behavior, a constant pressure-induced charge-transfer rate d n h /d p leads to a lineard T c /d p (n h ) behavior with positive pressure effects in the underdoped, an h oxygen content x Fig. 2: Hole concentration determined from T c , T c,max and the parabolic T c (n h ) behavior [8] versus oxygen content.n h ∆C p * T c [a .u .] d T c /d p [K /G P a ]Fig. 3: a) Pressure effect d T c /d p and b) ∆C p ⋅T c versus hole concentration in the CuO 2 planes.zero pressure effect in the optimally doped and negative pressure effects in the overdoped region. Exactly this behavior was found for n h > 0.11 foruniaxial c -axis pressure, determined either by direct measurements [13] or by thermal expansion measurements via Ehrenfest’s theorem [14-16].Data from these investigations areshown in the inset of Fig. 4. The solid line for n h > 0.11 in the inset ofFig. 4 is the derivative of the T c (n h )parabola with d n h /d p ≈ 3.7⋅10-3 GPa -1[17]. In this doping regime, T cchanges by uniaxial c -axis pressure are therefore mainly caused by charge transfer. Due to this simple behavior for n h > 0.11 we can divide off the effect of charge-transfer bysubtracting the solid line in the insetof Fig. 4 from our hydrostatic T c (p ) data. As a result we obtain a measure for the in-plane compression, namely the sum of a - and b -axis pressure effect [18].In Fig. 4 the effect of in-plane compression on T c , d T c /d p ab , shows nearly constant values in the overdoped and optimally doped regime. For pure Y123 d T c /d p ab rises in the underdoped region with decreasing doping down to n h > 0.11. For Nd123 this effect is smaller and almost absent for the Ca doped samples. The fact that this behavior is not correlated to charge transfer is confirmed by the quite similar looking pressure effect of La 2−x Ba x CuO 4 where charge-transfer effects are known to be absent [19].This coincidence points to a possible explanation for the T c (p ) peak at n h ≈ 0.11. For La 2−x Ba x CuO 4 the drastic collapse of T c at n h = 1/8 was interpreted to be caused by stripe pinning. Under pressure these stripes are depinned and T c recovers [20].For fully oxygenated R123 we find no argument for the existence of stripe pinning.But with a reduction of the oxygen content we have in Y123 well ordered CuO chains in an oxygen depleted neighborhood and such a configuration may pin stripes. This idea would also explain the different T c (p ) changes under uniaxial a - or b -axis pressure [14,15] because a compression perpendicular or parallel to the stripe direction would naturally cause different effects on stripe pinning. An analysis of the experimental data shown in Fig. 4 supports this idea. With decreasing hole content we find a drastic d T c /d p increase for Y123. For Nd123 with a much lower tendency to oxygen ordering this increase is dramatically diminished and for Ca doped samples with a large disorder in the oxygen sublattice we have almost no peak effect in d T c /d p .Another striking feature of an in-plane compression on T c of the different R123systems with quite different structural parameters is that they show a sharp decrease of d T c /d p below n h ≈ 0.11. At the same hole concentration also the c -axis pressure effect (that is attributed to pressure-induced charge-transfer) rapidly decreases. In addition we find other physical properties of different cuprate superconductors showing peculiarities at this hole content. The copper isotope effect dln(T c )/dln(m Cu ) of YBa 2Cu 3O x [21] and the oxygen isotope effects dln(T c )/dln(m O ) of La 2−x Ba x CuO 4 [22] and La 2−x Sr x CuO 4 [23] show drastic changes at n h ≈ 0.11, quite similar to the doping dependence of the thermalFig. 4: Non-charge-transfer pressure effect d T c /d p ab .Inset: d T c /d p c ·T c ,max -1 versus n h for Y123 (?, Refs. [13, 14),YCa123 (?, Refs. [15, 16]) and Nd123 (?, Ref. [16]). The solid line sketches the pure charge-transfer pressure effect calculated for d n h /d p ˜ 3.7·10-3 GPa -1 [17].resistivity of YBa 2Cu 3O x [24]. At n h ≈ 0.11 also the dopingdependence of the room-temperature thermopower of manycuprates changes from an exponential to a linear behavior[25]. Additionally, in La 1.6−x Nd 0.4Sr x CuO 4 atx = n h ≈ 0.11 the dopingdependence of the magnetic incommensurability ε, which is a measure for the distance of chargestripes, changes from ε = x to ε ≈ constant [26]. Hunt et al. [27]showed that below a hole contentn h ≈ 0.11 the amount of static stripes is increased drastically. From these arguments we conclude, that below n h ≈ 0.11 the physics in these materials is changing − above n h ≈ 0.11 we deal with a doped superconductor but below n h ≈ 0.11 we have to look at a doped antiferromagnet.In addition to the Ca doped R123 samples, we also investigated NdBa 2(Cu 0.98Zn 0.02)3O x single crystals. Zn is known to substitute for Cu in the CuO 2planes and to depress T c by pair-breaking effects. Therefore, n h could not be calculated from the parabolic T c (n h ) behavior. Assuming that Zn doping does influence neither the oxygen content achieved under certain annealing conditions nor the hole concentration in the CuO 2 planes, we estimated n h from the tempering conditions and the n h (x ) dependence of Zn free samples shown in Fig. 2. This assumption was confirmed for Zn-doped YCa123 [28].In Refs. [29] and [30] it was shown that around the Zn impurities small non-superconducting domains exist. Such non-superconducting domains may serve as pinning centers for stripes and would be independent of the oxygen content. In the pressure induced depinning picture one would then expect large pressure effects not only for underdoped samples but for fully oxygenated material, too. Fig. 5 shows the doping dependence of the pressure effects of our Zn doped samples in comparison to the pressure effects of the other R123 samples. At approximately optimum doping, where the pressure effects of the other samples are about 0.8 K/GPa the pressure effect of the Zn doped Nd123 samples is approximately 5 times larger. With decreasing hole concentration in the CuO 2 planes the pressure effect even increases to higher values than the maximum pressure effect of the Zn free Nd123 samples beeing consistent with the idea of pressure-induced depinning of stripes.4 Conclusions We measured T c , pressure effect d T c /d p and the specific heat of various Zn and Ca doped R123 single crystals and found two distinct charge carrier concentrations in the underdoped and overdoped region, where d T c /d p and ∆C p ⋅T c show distinct features. In the overdoped region around n h ≈ 0.175 superconductivity is very stable and T c changes under pressure are mainly caused by charge transfer. In the underdoped region the large pressure effects, which are not related to charge transfer, can be attributed to depinning ofn h d T c /d p [K /G P a ]Fig. 5: Pressure effect of Zn doped Nd123 (?) in comparison to the pressure effects of Zn free R123 samples.charged stripes. This idea is confirmed by the large pressure effect of Zn doped Nd123 samples even in the nearly optimally doped region. The breakdown of the pressure effects at n h < 0.11 with decreasing hole concentration is assigned to the crossover from a doped superconductor to a doped antiferromagnet.References1. S.A. Kivelson et al.; Nature393, 550 (1998).2. Y. Koike et al.; Proceedings of the 2000 international workshop onsuperconductivity, June 19-22, 2000; Shimane, Japan.3. J.D. Jorgensen et al.; Physica C 171, 93 (1991).4. R. Sieburger and J.S. Schilling; Physica C 173, 403 (1991). R. Benischke et al.;Physica C203, 293 (1992); W.H. Fietz et al.; Physica C 270, 258 (1996). V.G.Tissen et al.; Physica C316, 21 (1999).5. T.B. Lindemer et al.; J. Am. Ceram. Soc. 72, 1775 (1989).6. T.B. Lindemer et al.; Physica C255, 65 (1995).7. B. Fisher et al.; Phys. Rev. B 47, 6054 (1993); C. Glédel et al.; Physica C165, 437(1990).8. M.R. Presland et al.; Physica C176, 95 (1991); J.L. Tallon et al.; Phys. Rev. B51,12911 (1995).9. U. Tutsch et al.; J. of Low Temp. Physics117, 951 (1999).10. J.L. Tallon and J.W. Loram; cond-mat/0005063.11. J.D. Jorgensen et al.; Physica C171, 93 (1990).12. H.A. Ludwig et al.; Physica C197, 113 (1992).13. H.A. Ludwig, PhD Thesis, University of Karlsruhe (1998), FZKA6117; U. Welp etal.; J. of Supercond. 7, 159 (1994); U. Welp et al.; Phys. Rev. Lett. 69, 2130 (1992).14. O. Kraut et al.; Physica C205, 139 (1993).15. C. Meingast et al.; J. of Low Temp. Phys. 105, 1391 (1996).16. V. Pasler, PhD Thesis, University of Karlsruhe (1999), FZKA 6415.17. S.I. Schlachter et al., Physica C328, 1 (1999).18. W.H. Fietz et al.; to be published in Physica C.19. W.J. Liverman et al.; Phys. Rev. B 45, 4897 (1992).20. J.S. Zhou and J.B. Goodenough; Phys. Rev.B56, 6288 (1997).21. J.P. Franck and D.D. Lawrie; J. of Low Temp. Phys. 105, 801 (1996).22. M.K. Crawford et al.; Phys. Rev. B41, 282 (1990).23. G. Zhao et al.; J. Phys.: Cond. Mat. 10, 9055 (1998).24. J.L. Cohn et al.; Phys. Rev. B 59, 3823 (1999).25. S.D. Obertelli et al.; Phys. Rev. B 46, 14928 (1992).26. J.M. Tranquada et al.; Phys. Rev. Lett. 78, 338 (1997).27. A.W. Hunt et al.; Phys. Rev. Lett. 82, 4300 (1999).28. J.L. Tallon et al.; Phys. Rev. Lett. 75, 4114 (1995).29. B. Nachumi et al.; Phys. Rev. Lett. 77, 5421 (1996).30. S.H. Pan et al.; Nature403, 746 (2000).。