第52卷第10期2023年10月人㊀工㊀晶㊀体㊀学㊀报JOURNAL OF SYNTHETIC CRYSTALS Vol.52㊀No.10October,2023LaNbO 4ʒDy 3+,Ca 2+荧光粉的制备及发光性能研究陆㊀琴,方传利,王㊀游,吴冬妮,王誉洁,娄成龙(贵州师范大学物理与电子科学学院,贵阳㊀550025)摘要:为提高蓝绿色荧光粉的发光性能,本文采用传统的高温固相法合成LaNbO 4ʒDy 3+及LaNbO 4ʒDy 3+,Ca 2+荧光粉样品㊂通过测试样品的XRD㊁荧光光谱和CIE 色度坐标,研究Dy 3+单掺,Dy 3+㊁Ca 2+共掺对LaNbO 4荧光粉性能的影响㊂结果表明:LaNbO 4ʒDy 3+及LaNbO 4ʒDy 3+,Ca 2+荧光粉的衍射峰都与标准卡衍射峰的位置相匹配㊂样品的激发光谱均由两个宽带激发峰和一系列尖锐激发峰组成,LaNbO 4ʒDy 3+和LaNbO 4ʒDy 3+,Ca 2+样品的最强激发峰位分别是387和472nm㊂在波长为387nm 激发下,样品的最强发射峰值分别是575和477nm㊂且当Dy 3+掺杂浓度为0.05时,样品发光强度最佳㊂当Dy 3+和Ca 2+共掺,且Ca 2+浓度为0.05时,样品的发光性能最好㊂通过色卡坐标可以观察到在蓝绿色区域LaNbO 4ʒDy 3+,Ca 2+比LaNbO 4ʒDy 3+的坐标更加集中,由此可知Dy 3+和Ca 2+共掺LaNbO 4发光效果更好,发光性能更加稳定,表明该荧光粉是一种可被紫外光激发并且光致发光性能稳定的蓝绿色荧光粉㊂关键词:荧光粉;稀土铌酸盐;高温固相法;发光性能;共掺;蓝绿光中图分类号:TQ422;TN312+.8㊀㊀文献标志码:A ㊀㊀文章编号:1000-985X (2023)10-1816-06Preparation and Luminescence Properties of LaNbO 4ʒDy 3+,Ca 2+PhosphorsLU Qin ,FANG Chuanli ,WANG You ,WU Dongni ,WANG Yujie ,LOU Chenglong (School of Physics and Electronic Science,Guizhou Normal University,Guiyang 550025,China)Abstract :To improve the luminescence property of blue-green phosphors,the conventional high-temperature solid-phase method was used to synthesize LaNbO 4ʒDy 3+and LaNbO 4ʒDy 3+,Ca 2+phosphors in this paper.The XRD,fluorescence spectra and CIE chromaticity coordinates of the samples were tested to investigate the effects of Dy 3+doping and Dy 3+,Ca 2+co-doping on the performance of niobate phosphors.The results show that the diffraction peaks of LaNbO 4ʒDy 3+as well as LaNbO 4ʒDy 3+,Ca 2+phosphors all match the diffraction peaks of standard card.The excitation spectra of the samples are composed of two broadband excitation peaks and a series of sharp excitation peaks,the strongest excitation peaks of LaNbO 4ʒDy 3+and LaNbO 4ʒDy 3+,Ca 2+are 387and 472nm,respectively.Under excitation at a wavelength of 387nm,the strongest emission peaks of the sample are 575and 477nm,respectively.The best luminescence intensity is obtained when the concentration of Dy 3+doping is 0.05.When Dy 3+and Ca 2+are co-doped,the sample has the best luminescence property when the concentration of Ca 2+is 0.05.Through the color card coordinates,it can be observed that LaNbO 4ʒDy 3+,Ca 2+is more concentrated in the blue-green region than LaNbO 4ʒDy 3+,which shows that Dy 3+and Ca 2+co-doped LaNbO 4have better luminescence effect,and the co-doped samples show more stable luminescence property,indicating that the phosphor is a more stable blue-green phosphor that can be excited by UV light.Key words :phosphor;rare earth niobate;high temperature solid state method;luminescence property;co-doping;blue-green light ㊀㊀收稿日期:2023-03-12㊀㊀作者简介:陆㊀琴(1998 ),女,贵州省人,硕士研究生㊂E-mail:2801774023@ ㊀㊀通信作者:方传利㊂E-mail:20010070232@ 0㊀引㊀㊀言白光发光二极管(white light emitting diode,WLED)作为第四代照明光源,具有发光效率高㊁照明时间长㊁节能等优点,被广泛应用于探测㊁显示㊁医疗等领域[1-3]㊂目前主要有两种方式可以获得WLED,一种是由㊀第10期陆㊀琴等:LaNbO4ʒDy3+,Ca2+荧光粉的制备及发光性能研究1817㊀蓝色LED芯片和黄色荧光粉组合;另一种是通过近紫外LED芯片激发三基色(红㊁绿㊁蓝)荧光粉[4]㊂Dy3+作为一种常见的荧光粉激活剂,被近紫外光(350nm)激发时,会产生蓝色(470~500nm)和黄色(570~660nm)特征发射,这来自于电子从激发态4F9/2能级到基态6H15/2和6H13/2能级的跃迁[5-6],在特定的基质中发出白光而得到了广泛关注[7]㊂然而,对稀土掺杂荧光粉的发光性能来说,基质材料的选择也十分重要㊂常见的基质材料有硅酸盐㊁铝酸盐㊁铌酸盐等㊂硅酸盐荧光粉价格低㊁性质稳定,但是发光性能不好[8];铝酸盐荧光粉成本低,但是不够稳定[9]㊂铌酸盐是一种受温度影响小并且可以降解有机污染物的基质材料[10],由于其具有稳定的化学性质㊁良好的光学性能及低成本等优点被广泛应用于发光二极管㊁太阳能电池㊁金属离子检测㊁催化剂和激光等领域㊂其中,铌酸镧(LaNbO4)具有稳定的结构㊁较低的晶格声子能量[11],且其材料成本低,易获得,发光效率高,有利于提高上转换发光效率,是良好的发光基质[12-13]㊂近年来有许多关于铌酸盐荧光粉的研究报告㊂Yang等[14]通过水热法成功制备了GdNbO4ʒLn3+(Ln=Dy, Eu)单晶荧光粉,在Dy3+掺杂中,荧光粉样品在不同激发波长下有明亮的白色光发出,量子效率为21.1%;而当Eu3+掺杂时,荧光粉样品在近紫外光的激发下有明显的亮红色发出,这是由于[Nb4]3-基团的有效能量转移,量子效率为43.2%㊂Xiao等[15]采用常规的高温固相法成功制备了Li3Mg2NbO6ʒCr3+荧光粉,在蓝色光(460nm)的激发下,得到了拥有650~950nm宽带近红外发射荧光粉,这是由于Cr3+掺杂在不同的晶体场中取代了三个不同晶体位置的发射组成,表明Li3Mg2NbO6ʒCr3+荧光粉是宽带近红外的理想材料,为探索用于转换LED的新型过渡金属离子宽带近红外材料提供了重要参考㊂Lin等[16]通过熔盐法在1150ħ下合成了LiNbO3ʒPr3+,Mg2+钙钛矿结构长余辉红色荧光粉㊂其中由Mg2+代替基质中的Li+和Nb3-,形成Mg+和Mg3-的缺陷态,增加了费米能量,被认为在长余辉发光中起着关键作用,并提出了一种基于缺陷态在中间带隙跃迁的电荷弛豫机制㊂说明共掺二价离子对增强荧光粉发光性能有一定的研究意义,目前关于共掺二价离子增强LaNbO4ʒDy3+的光致发光特性研究很少㊂因此,本文首先通过高温固相法制备了掺杂Dy3+的LaNbO4荧光粉,并选择Ca2+共掺制备了LaNbO4ʒDy3+,Ca2+荧光粉,探究了掺杂不同浓度对荧光粉发光强度的影响㊂1㊀实㊀㊀验1.1㊀实验原料和制备方法本实验采用传统的高温固相法制备了铌酸镧荧光粉[17]㊂以La2O3(纯度99.9%)㊁Nb2O5(纯度99.9%)㊁Dy2O3(纯度99.9%)和CaCO3(纯度99.9%)为原料,分别制备了LaNbO4ʒx Dy3+(x=0.01㊁0.03㊁0.05㊁0.07)和LaNbO4ʒ0.05Dy3+,y Ca2+(y=0.01㊁0.03㊁0.05㊁0.07)荧光粉样品㊂将以化学式和掺杂比例称取好的原料放入研钵中研磨1h,使其充分混合,然后将样品装入坩埚在700ħ的空气中煅烧6h㊂让样品冷却到室温后,将样品再次研磨1h,在1200ħ的空气中进行二次煅烧3h,最后将样品研磨成粉进行进一步表征㊂1.2㊀性能测试样品的激发光谱和发射光谱是通过HORIBA公司的FIuoro max-4荧光光谱仪在室温下进行测试的,激发光源为氙灯150W,测量光谱范围为250~600nm㊂样品的物相表征采用日本科学智能实验室的X射线衍射仪,辐射源为Cu靶,管电流为150mA,扫描步长为0.02ʎ,扫描范围为10ʎ~80ʎ㊂色彩坐标的计算是根据光的辐射学和色度学的有关内容,利用光谱数据,根据国际照明委员会(Commission Internationale de lᶄEclairage,CIE)1931表的色系统中的坐标计算出色度坐标㊂2㊀结果与讨论2.1㊀LaNbO4ʒx Dy3+㊁LaNbO4ʒDy3+,y Ca2+荧光粉的物相分析图1(a)㊁(b)分别展示了样品LaNbO4ʒx Dy3+(x=0.01㊁0.03㊁0.05㊁0.07)㊁LaNbO4ʒ0.05Dy3+, y Ca2+(y=0.01㊁0.03㊁0.05㊁0.07)的XRD图谱㊂从图1可以看出,荧光粉样品主要衍射峰的位置与LaNbO4标准卡PDF#32-0496衍射峰的位置相匹配㊂在图1(a)中,10ʎ㊁23ʎ以及32ʎ左右的衍射峰与LaNbO3标准卡1818㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷PDF#45-0546衍射峰的位置较为匹配,由此可知该样品应为双相㊂而在图1(b)中,10ʎ左右的峰变弱,23ʎ处的衍射峰与LaNbO 3标准卡衍射峰的位置相匹配,最强衍射峰的位置由32ʎ向30ʎ偏移,表明荧光粉为双相㊂而最强衍射峰的偏移可能是煅烧时温度不均引起的内部残余应力导致晶格畸形㊂但是衍射峰尖锐,衍射强度高,表明晶型良好㊂图1不同浓度LaNbO 4ʒDy 3+㊁LaNbO 4ʒDy 3+,Ca 2+荧光粉的XRD 图谱Fig.1㊀XRD patterns of LaNbO 4ʒDy 3+,LaNbO 4ʒDy 3+,Ca 2+phosphors with different concentrations 2.2㊀LaNbO 4ʒx Dy 3+的激发光谱图分析图2是样品LaNbO 4ʒx Dy 3+(x =0.01㊁0.03㊁0.05㊁0.07)的激发光谱㊂从图中可观察到,当掺杂的Dy 3+浓度x =0.05时,样品的发光强度达到最大,而掺杂浓度为0.01时的发光强度紧随其后,当x =0.03时,其发光强度并不突出㊂浓度x =0.07时,荧光粉激发光谱强度明显降低,这是因为当浓度接近临界点时,Dy 3+离子之间会发生非辐射能量跃迁过程,发生浓度猝灭㊂激发光谱由在570nm 处监测到的300~500nm 一系列的显著峰形成,这主要是源于Dy 3+的电子从能级6H 15/2跃迁到亚稳能级6P 5/2㊁11G 4/2和4I 15/2,从而导致尖锐激发峰,其中显著激发峰的位置分别为387㊁427㊁451和473nm,最强激发峰为387nm,说明样品LaNbO 4ʒDy 3+在该处能被最有效激发㊂2.3㊀LaNbO 4ʒx Dy 3+的发射光谱图分析图3是样品LaNbO 4ʒx Dy 3+(x =0.01㊁0.03㊁0.05㊁0.07)的发射光谱㊂从图中可以观察到,在激发波长为387nm 时,样品LaNbO 4ʒDy 3+的发射光谱由450~600nm 的宽带及一系列锐利的发射峰组成,而且发射光谱的形状和位置基本不变㊂宽带是由[NbO 4]3--O 2-基团的电荷转移引起的,显著发射峰位分别在477和575nm,其中最强发射峰是575nm㊂这主要是源于Dy 3+在紫外光激发下出现的蓝色区域和黄色区域的特征发射,由477nm 处的磁偶极跃迁4F 9/2ң6H 15/2和575nm 处的电偶极跃迁4F 9/2ң6H 13/2组成㊂2.4㊀LaNbO 4ʒ0.05Dy 3+,y Ca 2+的激发光谱图分析图4所示是样品LaNbO 4ʒ0.05Dy 3+,y Ca 2+(y =0.01㊁0.03㊁0.05㊁0.07)的激发光谱㊂从图4可以观察到,随着掺杂Ca 2+浓度的浓度,LaNbO 4ʒDy 3+,Ca 2+荧光粉的发光强度逐渐增强,当Ca 2+浓度y =0.05时,激发光谱强度达到最强,浓度y =0.07时,激发光谱强度明显降低,这是因为当Ca 2+浓度接近临界值时,样品内形成了聚合体,并以非辐射的形式放出能量,而并不是将能量转移到掺杂的稀土离子中,说明Ca 2+浓度的大小可能成为能量转移的阻碍,从而导致荧光猝灭㊂共掺杂Dy 3+㊁Ca 2+荧光粉和单掺杂Dy 3+荧光粉样品的㊀第10期陆㊀琴等:LaNbO4ʒDy3+,Ca2+荧光粉的制备及发光性能研究1819㊀激发光谱的范围都是在300~500nm,显著激发峰的峰位相似,其中最显著激发峰为472nm㊂但是从图中可以看出,加入Ca2+之后的激发光谱的显著峰更多,峰值也更高㊂图2㊀LaNbO4ʒx Dy3+(x=0.01㊁0.03㊁0.05㊁0.07)荧光粉的激发光谱Fig.2㊀Excitation spectra of LaNbO4ʒx Dy3+ (x=0.01,0.03,0.05,0.07)phosphors图3㊀LaNbO4ʒx Dy3+(x=0.01㊁0.03㊁0.05㊁0.07)荧光粉在387nm激发下的发射光谱Fig.3㊀Emission spectra of LaNbO4ʒx Dy3+ (x=0.01,0.03,0.05,0.07)phosphors excited at387nm图4㊀LaNbO4ʒ0.05Dy3+,y Ca2+(y=0.01㊁0.03㊁0.05㊁0.07)荧光粉的激发光谱Fig.4㊀Excitation spectra of LaNbO4ʒ0.05Dy3+,y Ca2+ (y=0.01,0.03,0.05,0.07)phosphors图5㊀LaNbO4ʒ0.05Dy3+,y Ca2+(y=0.01㊁0.03㊁0.05㊁0.07)荧光粉在387nm激发下的发射光谱Fig.5㊀Emission spectra of LaNbO4ʒ0.05Dy3+,y Ca2+ (y=0.01,0.03,0.05,0.07)phosphors excited at387nm2.5㊀LaNbO4ʒ0.05Dy3+,y Ca2+的发射光谱图分析图5是样品LaNbO4ʒ0.05Dy3+,y Ca2+(y=0.01㊁0.03㊁0.05㊁0.07)的发射光谱㊂由图5可以观察到,在紫外光激发下LaNbO4ʒDy3+,Ca2+的发射光谱由450~600nm宽带和一系列锐利的发射峰组成,与LaNbO4ʒDy3+的发射光谱一致且峰值位置基本不变,分别集中于蓝色区域(477nm)及黄色区域(575nm)㊂而且可以看出Ca2+加入之后,样品的发射峰增强,尤其是在蓝色发射区域有明显增强的现象,这表明该样品在蓝色荧光粉中有潜在应用㊂2.6㊀LaNbO4ʒx Dy3+和LaNbO4ʒ0.05Dy3+,y Ca2+的CIE色度坐标分析利用LaNbO4ʒx Dy3+和LaNbO4ʒ0.05Dy3+,y Ca2+样品的发射光谱数据,通过CIE1931色度坐标计算软件得到相对应的CIE色度坐标㊂表1给出了样品LaNbO4ʒx Dy3+,LaNbO4ʒ0.05Dy3+,y Ca2+荧光粉的CIE坐标值㊂图6标出了LaNbO4ʒx Dy3+在387nm光激发下的CIE色度坐标位置㊂LaNbO4ʒx Dy3+的色度坐标计算结果表明,荧光粉样品的发光基本集中在色度坐标的蓝绿色区域,浓度的变化对发光颜色没有影响,这证明了LaNbO4ʒx Dy3+荧光粉在WLED上有一定的潜在应用㊂图7标出了LaNbO4ʒ0.05Dy3+,y Ca2+在387nm光激发下的CIE色度坐标位置㊂LaNbO4ʒ0.05Dy3+,y Ca2+的色度坐标计算结果表明,样品发光都集中在蓝绿色区域,随着Ca2+浓度不断增大,其发光更加集中于蓝色区域,色坐标基本没有发生改变,表明该荧光粉样品的光色呈现一致性㊂1820㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷表1㊀LaNbO 4ʒx Dy 3+和LaNbO 4ʒ0.05Dy 3+,y Ca 2+荧光粉在387nm 激发下的CIE 坐标值Table 1㊀CIE coordinates of LaNbO 4ʒx Dy 3+and LaNbO 4ʒ0.05Dy 3+,y Ca 2+phosphors excited at 387nmLabel point Sample Excitation wavelength /nm CIE coordinate1LaNbO 4ʒ0.01Dy 3+387(0.2669,0.3832)2LaNbO 4ʒ0.03Dy 3+387(0.2555,0.3721)3LaNbO 4ʒ0.05Dy 3+387(0.2741,0.3774)4LaNbO 4ʒ0.07Dy 3+387(0.2473,0.3721)5LaNbO 4ʒ0.05Dy 3+,0.01Ca 2+387(0.2769,0.3560)6LaNbO 4ʒ0.05Dy 3+,0.03Ca 2+387(0.2679,0.3599)7LaNbO 4ʒ0.05Dy 3+,0.05Ca 2+387(0.2740,0.3634)8LaNbO 4ʒ0.05Dy 3+,0.07Ca 2+387(0.2724,0.3601)图6㊀LaNbO 4ʒx Dy 3+(x =0.01㊁0.03㊁0.05㊁0.07)荧光粉在387nm 激发下的CIE 坐标图Fig.6㊀CIE coordinates of LaNbO 4ʒx Dy 3+(x =0.01,0.03,0.05,0.07)phosphors excited at 387nm 图7㊀LaNbO 4ʒ0.05Dy 3+,y Ca 2+(y =0.01㊁0.03㊁0.05㊁0.07)荧光粉在387nm 激发下的CIE 坐标图Fig.7㊀CIE coordinates of LaNbO 4ʒ0.05Dy 3+,y Ca 2+(y =0.01,0.03,0.05,0.07)phosphors excited at 387nm 3㊀结㊀㊀论本文采用高温固相法制备了不同浓度的LaNbO 4ʒDy 3+和LaNbO 4ʒDy 3+,Ca 2+荧光粉样品,研究其光致发光性能㊂XRD 图谱显示,样品的衍射峰均与标准卡的数据吻合良好㊂结合激发光谱㊁发射光谱和CIE 色度坐标图分析,样品的猝灭浓度都为0.05,LaNbO 4ʒDy 3+中的Dy 3+之间和LaNbO 4ʒDy 3+,Ca 2+中的Ca 2+之间都会发生非辐射能量跃迁过程,发生浓度猝灭,说明掺杂浓度到达临界值时会阻碍能量转移㊂而且共掺Ca 2+后没有改变Dy 3+的发射峰位置,但在蓝色发射区域有明显的增强,且样品的色坐标都集中在蓝绿色区域,证明掺杂Ca 2+后样品发光性能更加稳定,也表明了LaNbO 4ʒDy 3+㊁LaNbO 4ʒDy 3+,Ca 2+荧光粉是一种具有应用前景的蓝绿色荧光材料㊂参考文献[1]㊀刘芳芳,赵㊀旺,孙春艳.基于LED 用红色荧光粉研究进展的研究[J].无线互联科技,2020,17(2):126-127.LIU F F,ZHAO W,SUN C Y.Research on progress of red phosphor based on LED[J].Wireless Internet Technology,2020,17(2):126-127(in Chinese).[2]㊀怀素芳,李㊀旭,崔敏敏.新一代照明光源白光LED 的发展概况[J].物理通报,2007(11):53-55.HUAI S F,LI X,CUI M M.Development of white LED as a new generation of lighting source[J].Physics Bulletin,2007(11):53-55(inChinese).[3]㊀李高锋.蓝光激发的白光LED 用荧光粉的研究[D].杭州:中国计量学院,2012.LI G F.Investigation on phosphors under blue light excitation for white light emitting diodes[D].Hangzhou:China University of Metrology,2012(in Chinese).[4]㊀江鹏强.三基色荧光玻璃制备及其白光LED 封装应用研究[D].武汉:华中科技大学,2018.㊀第10期陆㊀琴等:LaNbO4ʒDy3+,Ca2+荧光粉的制备及发光性能研究1821㊀JIANG P Q.Preparation of multi-color phosphor-in-glass and its application for LED packaging[D].Wuhan:Huazhong University of Science and Technology,2018(in Chinese).[5]㊀王林香,孙德方,李㊀晴,等.Dy3+和Ce3+共掺Y3Al5O12荧光粉的制备及发光性质[J].发光学报,2020,41(2):160-167.WANG L X,SUN D F,LI Q,et al.Luminescent properties of Dy3+,Ce3+co-doped Y3Al5O12phosphors[J].Chinese Journal of Luminescence,2020,41(2):160-167(in Chinese).[6]㊀韩华丽.LaNbO4基稀土掺杂(Ln=Dy,Tb,Eu,Sm)材料的制备及发光性质的研究[D].长春:东北师范大学,2013.HAN H L.Preparation and luminescence properties of LanbO4-based rare-earth-doped(Ln=Dy,Tb,Eu,Sm)[D].Changchun:Northeast Normal University,2013(in Chinese).[7]㊀GAO H Y,LI P L.Luminescence and energy transfer of white emitting phosphor Ba3Ce(PO4)3ʒDy3+[J].Optik,2018,170:272-277.[8]㊀张丁非,汤㊀安,杨㊀柳,等.基于硅酸盐体系白光LED用荧光粉的研究现状[J].材料导报,2010,24(21):5-9.ZHANG D F,TANG A,YANG L,et al.Progress based on silicate system as white-light phosphors used for LED[J].Materials Review,2010, 24(21):5-9(in Chinese).[9]㊀夏㊀茂,曾少波,王姣忠.白光LED用铝酸盐荧光粉的研究进展[J].中国照明电器,2015(1):9-12.XIA M,ZENG S B,WANG J Z.Research progress on photoluminescence phosphors of aluminate for white LEDs[J].China Light&Lighting, 2015(1):9-12(in Chinese).[10]㊀陈㊀浩,刘㊀琳,徐飞翔,等.Sm3+掺杂LnNbO4(Ln=La,Y)红色荧光粉的性能分析[J].厦门理工学院学报,2020,28(5):81-88.CHEN H,LIU L,XU F X,et al.A study on the properties of Sm3+doped LnNbO4(Ln=La,Y)red phosphors[J].Journal of Xiamen University of Technology,2020,28(5):81-88(in Chinese).[11]㊀张志力,翟洪祥,金宗哲,等.正铌酸镧(LaNbO4)及其掺杂粉体的发光特性[J].中国稀土学报,2003,21(S1):8-12.ZHANG Z L,ZHAI H X,JIN Z Z,et al.Luminescence properties of LaNbO4and(La,Tb)NbO4powders[J].Journal of the Chinese Rare Earth Society,2003,21(S1):8-12(in Chinese).[12]㊀张焕君,董兴邦,彭㊀科,等.LaNbO4ʒTm,Yb荧光材料的上转换发光及温度传感特性研究[J].化工新型材料,2020,48(8):263-266.ZHANG H J,DONG X B,PENG K,et al.Upconversion luminescence and temperature sensing property of LaNbO4ʒTm,Yb phosphor[J].New Chemical Materials,2020,48(8):263-266(in Chinese).[13]㊀王㊀伟,朱红波.水热法合成NaYF4ʒYb3+-Er3+及其上转换发光性质[J].人工晶体学报,2018,47(8):1742-1746.WANG W,ZHU H B.Hydrothermal synthesis of NaYF4ʒYb3+-Er3+and its up-conversion luminescence properties[J].Journal of Synthetic Crystals,2018,47(8):1742-1746(in Chinese).[14]㊀YANG M,ZHAO X D,JI Y,et al.Hydrothermal approach and luminescent properties for the synthesis of orthoniobates GdNbO4ʒLn3+(Ln=Dy,Eu)single crystals under high-temperature high-pressure conditions[J].New Journal of Chemistry,2014,38(9):4249-4257. [15]㊀XIAO F,XIE C N,XIE S K,et al.Multi-site Cr3+occupation-related broadband NIR luminescence in Cr3+-doped Li3Mg2NbO6[J].CrystEngComm,2021,23(33):5585-5594.[16]㊀LIN S P,XIONG C W,MA D C,et al.Persistent luminescence found in Mg2+and Pr3+co-doped LiNbO3single crystal[J].Journal ofMaterials Chemistry C,2018,6(37):10067-10072.[17]㊀林㊀莹,高绍康.白光LED用荧光粉制备方法的研究与分析[J].广东化工,2020,47(12):137-138.LIN Y,GAO S K.The preparation method research and analysis of phosphors for white LED[J].Guangdong Chemical Industry,2020,47(12): 137-138(in Chinese).。