Effect of Sr^2＋ on Properties of Li0.2375＋xLa0.5875-xSrxTiO3-LaPO4 System

Ionicconductingsolidmaterialshavereceivedconsiderableattentioninthelastfewyearsduetotheirpotentialutilityinhighenergybatteriesandotherelec trochemicaldevices .SeveralsystemsoflithiumfastionconductorsareknowntoshowhighlithiumionconductivitysuchasγLi3PO4 typesolidsolution[1] ,LiTi2 (PO4 ) 3anditsderivations[2～4 ] andLi14 Zn(GeO4 ) 3solidsolution[5] .However ,exceptforlowpowerapplications ,onemajorproblemwiththepracticalapplicationsisitslowconductivityatroomtemperature .Recentyears ,morean…     

Preparation of Solid Solutions [Li3xLa0.67-xYyTi1-2yNbyO3] and Its Lithium-ion Conductivity

Ａｗｉｄｅｖａｒｉｅｔｙｏｆｆａｓｔｉｏｎｃｏｎｄｕｃｔｏｒｓ (ａｌｓｏｂｅｃａｌｌｅｄａｆｔｅｒｓｏｌｉｄｅｌｅｃｔｒｏｌｙｔｅｓ)ｗｉｔｈｈｉｇｈｉｏｎｉｃｃｏｎｄｕｃｔｉｖｉｔｙｈａｓｂｅｅｎｄｉｓｃｏｖｅｒｅｄｆｏｒｔｈｅｌａｓｔｔｗｏｄｅｃａｄｅｓ[1 ] .ＬｉｔｈｉｕｍｉｏｎｃｏｎｄｕｃｔｏｒｓａｒｅａｍｏｎｇｔｈｅｍｏｓｔａｔｔｒａｃｔｉｖｅｂｅｃａｕｓｅＬｉｓｙｓｔｅｍｈｏｌｄｓｔｈｅｇｒｅａｔｐｒｏｍｉｓｅｔｏｂｅｕｓｅｄｉｎｈｉｇｈｅｎ ｅｒｇｙｄｅｎｓｉｔｙｂａｔｔｅｒｉｅｓ ,ｄ…     

Interactions in the LiPO3 — MoO3, NaPO3 — MoO3, and KPO3 — MoO3 systems

The MPO₃ — MoO₃ (M=Li, Na, K) pseudobinary systems have been examined by differential thermal analysis and x-ray phase analysis. The phase diagrams have been derived, and the temperatures and compositions of the eutectics have been determined. The compounds have been examined by x-ray phase analysis, infrared spectroscopy, and diffuse reflection spectroscopy. The conductivity and optical properties of the compounds MMoO₂(PO₄) (M=Li, Na, K) have been determined. The coordinates of the liquidus lines have been used to calculate the activities of the components in the MPO₃ — MoO₃ systems. Those activities show large negative deviations from ideal solutions. This indicates strong interaction between particles in the liquid state. Translated from Poroshkovaya Metallurgiya, Nos. 3–4(412), pp. 33–40, March–April, 2000.     

Microwave dielectric properties of Ba6-3xLa8+2x(Ti1-zZrz)18O54(x=2/3)ceramics

Zr substitution for Ti was investigated to modify the dielectric properties of Ba6-3xLa8+2xTi18O54(x=2/3) ceramics.A single-phase solid solution with tungstenbronze-like structure was formed in the range of 0     

CaMoO_4∶Eu~(3+),M~+(M=Li,Na,K)粉体的制备与发光性能研究

采用溶胶-凝胶法制备了Ca_(1-1.5x)MoO_4∶xEu~(3+)和Ca_(0.5)MoO_4∶0.25Eu~(3+),M~+(M=Li,Na,K)荧光粉,并对样品的物相结构、颗粒形貌及发光性能进行了分析。结果表明,样品属于四方晶系,颗粒接近八面体形状,大小为2~3μm。激发光谱显示,样品的激发中心分别位于364 nm、386 nm、396 nm、419 nm和466 nm,最大激发峰值位于396 nm。在396 nm近紫外光激发下,样品的发射中心分别位于596 nm、616 nm、656 nm、704 nm,特征发射峰为616 nm,Eu3+离子掺杂浓度为25%(体积分数)时发光强度最强,引入的3种电荷补偿剂M~+(M=Li,Na,K)中,Li+对发光强度的提高最为显著。     

MNO_3–Ca(NO_3)_2 (M=Li,Na,K)二元相图的热力学优化

基于CALPHAD方法对MNO3-Ca(NO3)2(M=Li,Na,K)二元相图的试验数据首次进行了热力学优化拟合,得到了3个二元相图的过量混合热力学性质的参数及Ca(NO3)2的熔化吉布斯自由能随温度变化的函数表达式,并用拟合的参数计算了3个二元相图,最后将计算得到的相图与试验相图进行了比较。     

Ti掺杂LiNiO2第一性原理研究

采用基于密度泛函理论的第一性原理超软贋势平面波法,对Ti掺杂LiNiO₂的几何结构进行优化,计算其晶体结构、原子布局、态密度、能带结构及电子结构.结果表明: Ti掺杂LiNiO₂,降低系统能量,结构更加稳定,并且使得晶胞参数c及c/a比值增大,层间距增大,有利于Li+脱嵌和迁移,从而改善其电化学性能;同时, 掺杂Ti影响周边O和Ni电子排布,使得周边O-Ni键增长, 减弱O与Ni之间的相互作用,O-Ti与O-Ni键长相近,抑制因Jahn-Teller效应导致的八面体扭曲,增强结构稳定性,改善循环性能;Ti掺杂还使得禁带宽度、能隙及电子跃迁所需能量均减小,且此时Li在材料中以离子形态存在,有利于脱嵌和扩散,增强导电性.      

AlF3-(Li,Na)F-(Al2O3-Y2O3)熔盐体系物理化学性质研究

为进一步优化电解制备Al-Cu-Y合金的热、动力学条件,对AlF₃-(Li, Na)F-(Al₂O₃-Y₂O₃)熔盐体系的密度、黏度及电导率变化规律进行研究。分别采用阿基米德法、连续变化电导池常数法和旋转法测定AlF₃-(Li, Na)F-(Al₂O₃-Y₂O₃)熔盐体系在温度为900~1 000 ℃范围内,n((Li, Na)F): n(AlF₃)=2.5时的密度(ρ)、电导率(σ)、黏度(η)随温度和组分的变化规律,结果表明:在温度900~1 000 ℃范围内,AlF₃-(Li, Na)F-(Al₂O₃-Y₂O₃)体系中Al₂O₃和Y₂O₃的含量一定,密度-温度、黏度-温度和电导率-温度之间均呈线性关系。在温度为950 ℃条件下,熔盐体系的密度随Al₂O₃含量的增加而线性减小,随Y₂O₃含量的增加而线性增加; 电导率随Y₂O₃或Al₂O₃含量的增加而线性减小; 体系的黏度则随Y₂O₃或Al₂O₃含量的增加而线性增加。      

Hydrothermal synthesis and luminescent properties of BaMoO_4:Sm~(3+) red phosphor

Trivalent samarium doped barium molybdate(BaMoO_4:Sm~(3+)) red phosphor was successfully synthesized by hydrothermal method. The crystal structure, morphology and photoluminescent property were characterized by X-ray diffraction, field environmental scanning electron microscopy and photoluminescence spectroscopy. The results indicated that the synthesized BaMoO_4:Sm~(3+)phosphor consisted of a pure phase with an octahedral structure. The main excitation peaks were located at 362, 404, 445 and 477 nm, respectively, and were obviously observed. The main emission peaks were located at 533, 566, 602 and 646 nm, respectively. The phosphors exhibited a red performance at 646 nm, which was appropriate for the ultraviolet-light emitting diode(UV-LED) and blue LED. The luminescent intensity of BaMoO_4:Sm~(3+) increased with an increase in the doping amount of Sm~(3+). The luminescent intensity had the optimal value for x=0.03. When the doping amount of Sm~(3+) was further increased, the concentration quenching phenomenon was observed. Monovalent lithium(Li+) cation was used as a charge compensator. The luminescence intensity first increased with increasing Li+ doping concentration, and then decreased. The optimal content of Li+ was about 2%. The BaMoO_4:Sm~(3+) phosphor prepared in this study could act as superior red phosphor for white LEDs.     

Thermodynamic studies and the phase diagram of the Li-Mg system

By means of the electromotive force (emf) method of concentration cells of the following scheme: Li (1) / LiCl-LiF (eut) or LiCi-KCl (eut) / Li-Mg (1) or Li (1) / LiCl-LiF (eut) / Li-Mg (s) Li activities for liquid and solid alloys at the (Mg), (Li), and (Mg) + (Li) two-phase region of the Li-Mg system were determined. Liquid alloys were examined at temperatures from 638 to 889 K at various Li concentrations. The (Mg) solid solutions were investigated in two series: at constant temperatures between 773 and 876 K, with varying Li content, and at fixed Li concentrations, equal to 0.125 and 0.160 molar fractions, at different temperatures between 772 and 849 K. At the two-phase region, (Mg) + (Li), emf measurements were performed in the temperature range 773 to 838 K, with fixed Li concentrations equal to 0.20, 0.25, and 0.275 molar fractions. For (Li) solid alloys, experiments were done at temperatures 773 to 849 K for several constant Li concentrations, between 0.30 to 0.45 molar fractions, respectively. Studies on solid alloys enabled us also to determine the boundaries (Li)/[(Mg) + (Li)] and (Mg)/[(Mg) + (Li)] at temperatures 773 to 831 K. The resulting thermodynamic and phase boundary data of this study were used with other selected references for a critical assessment of the Li-Mg system. The Lukas BINGSS optimization program and BINFKT for the calculation of the thermodynamic functions and of the phase diagram were used. The calculated equilibrium phase diagram at temperatures below 750 K indicates a slightly lower solid solubility of Mg in (Li) in comparison with results from thermal analysis and the recently published Saunders evaluation.