铅在铋系110K超导相中的位置和作用

研究表明铅离子既可进入110K 相中铋离子的格位也可以进入锶离子的格位.铅离子主要占据的格位与样品的名义组成有关.铅离子的掺杂有利于110K 相的形成,但若铅离子进入锶离子格位将使110K 相的性质变坏.     

RE1—xBxF3—y（RE=Y,La,Ce,Gd;B=Ca,Ba）的敏感性质的研究

LaF_3作为离子选择性电极和对气体的敏感性质已进行了一定的研究,但其他稀土氟化物的敏感性质却未见报道。本文合成了RE_(1-x)B_xF_(3-y),研究了它们的结构、电学性质及敏感性质,得到有可能在150℃使用的固体电解质氧敏材料。 (一) RE_(1-x)B_xF_(3-y)的结构分析 结构分析表明,Ca、Ba置换RE的含量少时,如La_(0.95)Ba_(0.05)F_(3-y)、Ce_(0.95)Ca_(0.05)F_(3-y)的X射线衍射分析结果与LaF_3、CeF_3相似,说明它们是固溶体。而Ca置换RE含量较多时,如Y_(0.71)Ca_(0.29)F_(3-y)、Gd_(0.85)Ca_(0.15)F_(3-主)的X射线衍射分析结果却与相应的YF_3和GdF_3完全不     

铅在铋系110K超导相中的位置和作用

研究表明铅离子既可进入110K 相中铋离子的格位也可以进入锶离子的格位.铅离子主要占据的格位与样品的名义组成有关.铅离子的掺杂有利于110K 相的形成,但若铅离子进入锶离子格位将使110K 相的性质变坏.     

LaSr2-xCaxV3O9±y的制备、结构和价态影响

采用新的合成方法制备了一类新的化合物LaSr2-xCaxV3O9±y, X射线粉末衍射分析证实它们是单一化合物。利用计算机及自编软件对其进行了指标化并计算了它们的晶胞常数。结构数据表明, 随钙含量的增加, LaSr2-xCaxV3O9±y发生了从立方到正交到立方的相转变。热重和光电子能谱表明, 新化合物中的钒是以V^3^+和V^4^+的低价态形式存在, 它们具有较低的电阻率。     

110K铋基超导相形成的组成条件

Bi-Sr-Ca-Cu-O超导材料中存在110K和80K2个超导相。其组成是Bi_2Sr_2Ca_2Cu_3O_y和Bi_2Sr_2CaCu_2O。但迄今为止,在按2223组成比合成的未掺杂Bi系超导材料中从未得到过纯的110K相,也未见过组成为2223,零电阻温度在100K以上材料的报道。为了探索形成110K相的最佳条件,本文以2223组成比为参考,合成了5个系列材料:Bi_xSr_2Ca_2Cu_3O_y,Bi_2Sr_xCa_2Cu_3O_y,Bi_2Sr_2Ca_xCu_3O_y,Bi_2Sr_2Ca_2Cu_xO_y,Bi_i Sr_uCa_yCu_wO_s。     

Sol-gel synthesis and electrical properties of ceria-based solid electrolytes

A series of solid electrolytes (Ce_(0.8)RE_(0.2))_(1-x)M_xO_(2-δ)(RE: Rare earth, M: Alkali earth) were prepared by sol-gel methods. XRD indicated that a pure fluorite phase was formed at 800℃. The synthesis temperature by the sol-gel methods was about 700℃ lower than by the traditional ceramic method. The electrical conductivity and impedance spectra were measured. XPS showed that the oxygen vacancy increased obviously by doping MO, thus, resulting in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte was improved. The effects of RE_2O_3 and MO on the electrical properties were discussed. The conductivity and the oxygen ionic transport number of (Ce_(0.8)Sm_(0.2))_(1-0.05)Ca_(0.05)O_(2(?)δ) is 0.126 S·cm~(-1) and 0.99 at 800℃, respectively.     

(Ce0.8RE0.2)1-xMxO2-δ固体电解质的溶胶-凝胶合成及其电性质

利用溶胶 凝胶法合成了 (Ce0 .8RE0 .2 ) 1-xMxO2 -δ(RE :稀土 ,M :碱土 )系列固体电解质 ,XRD表明 80 0℃即形成萤石结构 ,较高温固相反应合成温度低约 70 0℃ .测定了样品的电导率和阻抗谱 .XPS测试表明 ,掺杂碱土氧化物后吸附氧浓度明显增大 ,氧空位增多 ,电导率和氧离子迁移数增大 ,改善了CeO2 基固体电解质的性能 .讨论了碱土及稀土离子对电性质的影响 .(Ce0 .8Sm0 .2 ) 1-0 .0 5 Ca0 .0 5 O2 -δ80 0℃时电导率0 1 2 6S·cm-1,氧离子迁移数 0 .99.     

Low temperature preparation and fuel cell properties of rare earth doped barium cerate solid electrolytes

The solid electrolytes, BaCe_(0.8) Ln_(0.2)O_(2.9) (Ln: Gd, Sm, Eu), were prepared by the sol-gel method. XRD indicated that a pure orthorhombic phase was formed at 900℃. The synthesis temperature by the sol-gel method was about 600℃ lower than the high temperature solid phase reaction method, The electrical conductivity and impedance spectra were measured and the conduction mechanism was studied. The grain-boundary resistance of the solid electrolyte could be reduced or eliminated by the sol-gel method. The conductivity of BaCe_(0.8)Gd_(0.2)O_(2.9) is 7.87×10~(-2) S·cm~(-1) at 800℃. The open-circuit voltage of hydrogen-oxygen fuel cell using BaCe_(0.8) Gd_(0.2)O_(2.9) as electrolyte was near to 1 V and its maximum power density was 30 mW·cm~(-2).     

磷化镝与磷化镱的光学性质和电学性质

用X射线衍射法确定了DyP和YbP的晶体结构,研究了它们的吸收光谱。得出其禁带宽度分别为1.15eV和1.30eV,电阻率为～10~(-2)Ω-cm,载流子浓度约10~(18)～10~(19)cm~(-3),霍尔迁移率8.5—80cm~2/V·s。它们与P型Si有明显的整流效应,表明形成了DyP/Si和YbP/Si异质结。文中提出了它们的可能能带图,解释了它们的光学性质和电学性质。