LiErP4O12的晶体结构

对于盐熔法合成的LiErP₄O₁₂单晶进行了X射线衍射分析。该晶体属于单斜晶系,空间群为C2/c,z=4,晶胞参数为:a=16.229?,b=7.009?,c=9.524?,β=125.92°。包括把二次消光作为晶体结构参数的全矩阵最小二乘法修正给出1282个独立反射的R=0.058。基本的结构单位为(PO₃)_n的螺旋带,它们由共角的四面体构成。十二面体ErO₈不共有任何O原子,从这意义来说是相互分立的。 关键词：     

LiNdP4O12的晶体结构

对于盐熔法合成的LiNdP₄O₁₂单晶进行了X射线衍射分析,该晶体属于单斜晶系,空间群为C2/c,z=4,晶胞参数为:α=16.486?,b=7.073?,c=9.775?,β=126.23°,全矩阵最小二乘法修正给出1251个独立反射的R=0.054,R_ω=0.050,经吸收和次级消光校正后,R=0.048,R_ω=0.043,基本的结构单位是(PO₃)_n的螺旋带,它们由共角 关键词：     

Y2O3·Cr2O3复合氧化物热力学性质的研究

在1182—1386K温度范围内,用固体电解质氧浓差电池:Mo|Cr,Y₂O₃,Y₂O₃·Cr₂O₃|ZrO₂(+MgO)|Cr,Cr₂O₃|Mo测定了复合氧化物Y₂O₃·Cr₂O₃的热力学性质。对于反应Y_{2关键词：}     

Synthesis and properties of Au-Fe3O4 and Ag-Fe3O4 heterodimeric nanoparticles

Monodisperse Au-Fe 3 O 4 heterodimeric nanoparticles (NPs) were prepared by injecting precursors into a hot reaction solution.The size of Au and Fe 3 O 4 particles can be controlled by changing the injection temperature.UV-Vis spectra show that the surface plasma resonance band of Au-Fe 3 O 4 heterodimeric NPs was evidently red-shifted compared with the resonance band of Au NPs of similar size.The as-prepared heterodimeric Au-Fe 3 O 4 NPs exhibited superparamagnetic properties at room temperature.The Ag-Fe 3 O 4 heterodimeric NPs were also prepared by this synthetic method simply using AgNO 3 as precursor instead of HAuCl 4.It is indicated that the reported method can be readily extended to the synthesis of other noble metal conjugated heterodimeric NPs.     

用会聚束电子衍射测定LiZnTa3O9,LiCaTa3O9的对称性

本文用会聚束电子衍射方法测定了我们生长的新晶体LiZnTa₃O₉和LiCaTa₃O₉的对称性,得出LiZnTa₃O₉晶体属三方晶系,点阵参数a=0.557nm,a=56.12°,点群为3m,空间群为R3c。LiCaTa₃O₉晶体属四方晶系,点阵参数a=0.778nm,c=0.783nm,点群为4/mmm。 关键词：     

Al2O3增强的Co2-C98/Al2O3/Si异质结的光伏效应

随着能源危机的加剧,太阳能电池作为开发和利用太阳能的一种普遍形式, 日益受到世界各国的重视.随着太阳能电池向着高效率、薄膜化、无毒性和原材料丰富的方向发展, 单纯的硅系太阳能电池已经无法达到这样的要求,因此新的材料和工艺的开发利用迫在眉睫. 本文研究了碳材料在硅异质节上实现光伏效应的改善及其可能在太阳能电池上的应用. 采用脉冲激光沉积方法制备的Co₂-C₉₈/Al₂O₃/Si异质结构在标准日光照射 (AM1.5, 100 mW/cm²)条件下,可获得0.447 V的开路电压和18.75 mA/cm²的电流密度, 转换效率可达3.27%.通过电容电压特性和暗条件下的电输运性能测量, 证明了氧化铝层的引入不但对单晶硅的表面起到了物理钝化作用,减小了反向漏电流, 使异质结界面缺陷、界面能级和复合中心减少,还起到了场效应钝化作用, 增加了异质结界面的势垒高度,增加了开路电压,使异质结的光伏效应显著增强.     

Preparation and characteristics of?a?BaO–Al2O3–B2O3–SiO2–La2O3 glass ceramic via spray pyrolysis

The characteristics of a BaO–Al₂O₃–B₂O₃–SiO₂–La₂O₃ glass ceramic prepared by spray pyrolysis were studied. Glass powders with spherical shape and amorphous phase were prepared by complete melting at a preparation temperature of 1 500°C. The mean size and geometric standard deviation of the powders prepared at the temperature of 1 500°C were 0.6 μm and 1.3. The glass powders had similar composition to that of the spray solution. The glass transition temperature (T _g) of the glass powders was 600.3°C. Two crystallization exothermic peaks were observed at 769.3 and 837.8°C. Densification of the specimen started at a sintering temperature of 600°C, in which Ba₄La₆O(SiO₄)₆ as main crystal structure was observed. Complete densification of the specimen occurred at a sintering temperature of 800°C. The specimens sintered at temperatures above 800°C had main crystal structure of BaAl₂Si₂O₈.     

La2O3对Yb:Y2O3透明陶瓷光谱性能的影响

研究了La₂O₃对Yb：Y₂O₃透明陶瓷光谱性能的影响，添加适量La₂O₃以后，Yb：Y₂O₃透明陶瓷的吸收峰和发射峰的位置不变，但由于La³⁺的离子半径大于Y³⁺的离子半径，在Y₂O₃中引入La³⁺离子后，导致Y₂O₃晶格常数变大，晶场强度变弱，同时降低了Y₂O₃晶体的有序度，致使发射峰强度有所下降，发射截面变小.过量的La₂O₃（x=0.16）造成Yb³⁺激活离子发射强度明显下降；其荧光寿命在添加La₂O₃后总体增大45%—60%. 关键词： 氧化镧 氧化钇 透明陶瓷 光谱性能     

CoFe2O4和MnFe2O4纳米复合介质的制备及其磁性研究

采用热分解法制备了分散程度高且平均晶粒尺寸为20 nm的CoFe₂O₄和MnFe₂O₄复合介质.低温磁化曲线测量显示,制备的复合介质具有软-硬磁交换弹性耦合效应,且合成温度以及软磁和硬磁相的成分比例对磁交换弹性耦合的强度有很大的影响.变温磁测量显示,温度为20K时,复合纳米介质的表面自旋冻结效应导致饱和磁化强度显著增加.Henkel测量显示,对分散的CoFe₂O₄和MnFe₂O₄复合介质,磁偶极相互作用占主导作用.     

Exchange bias behavior of monodisperse Fe3O4/γ-Fe2O3 core/shell nanoparticles

We have carried out systematic studies on well-characterized monodisperse Fe₃O₄/γ-Fe₂O₃ core/shell nanoparticles of 2-30 nm having a very narrow size distribution and possessing a uniquely mono-layer of surface γ-Fe₂O₃. This unique core-shell structure, probably having a disordered magnetic surface state, leads us to three key observations of unusual magnetic properties: i) a very large magnetic exchange anisotropy reaching over 7 × 10⁶ erg/cm³ for the smaller particles, ii) exchange bias behavior in the magnetization data of the core/shell Fe₃O₄/γ-Fe₂O₃ nanoparticles, and iii) the temperature dependence of the coercive field following an unusual exponential behavior.     

LiAl5O8高压相变研究

 运用金刚石压砧同步辐射X射线衍射,对尖晶石结构的LiAl₅O₈进行了高压原位研究。实验发现：在高压下,一组LiAl₅O₈的新相衍射峰出现,随着压力的增加,其新相衍射峰逐渐增强,当压力增加到45.0 GPa时,LiAl₅O₈的低压相衍射峰全部消失,而形成了一组高压新相衍射峰。采用指标化程序对衍射数据进行处理和分析,确定这一高压新相为正交晶系结构,其晶胞参数为a=0.995 9 nm,b=0.644 7 nm,c=0.333 4 nm ,空间群为Pmm2。     

Eu2O3在η-Al2O3和SiO2上固体-固体表面相互作用的研究

用穆斯堡尔谱和X射线衍射技术研究了Eu₂O₃在η-Al₂O₃和硅胶上的固体表面吸附。 关键词：     

PbBi2Nb2O9的晶体结构

PbBi₂Nb₂O₉晶体属正交晶系,空间群为D_2h²³-Fmmm。晶胞参数为a=5.4806(7)?,b=5.4791(7)?,c=25.416(3)?,α=β=γ=90.0(0)°,V=763.2(2)?³。单位晶胞内化学式数z=4,D_obs=7.91g/cm³,D_x=8.26g/cm³ 关键词：     

BaO-Li2O-B2O3三元系中BaB2O4-Li2B2O4和BaB2O4-Li2O截面相平衡关系的研究

本文用X射线和差热分析方法对BaO-Li₂O-B₂O₃三元系中的两个截面:BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O作了研究。在BaB₂O₄-Li₂B₂O₄赝二元系中发现了一个新的化合物4BaB₂O₄·Li₂B₂O₄。化合物在930±3℃由包晶反应形成,并与Li₂B₂O₄形成共晶反应。共晶温度为797±3℃,共晶点组分为79mol％Li₂B₂O₄。在BaB₂O₄-Li₂O截面中也存在化合物4BaB₂O₄·Li₂B₂O₄,其包晶反应温度从930±3℃随Li₂O含量增加下降到908±3℃。在组分60mol％Li₂O处形成另一个新的化合物2BaB₂O₄·3Li₂O。该化合物在630±3℃也是由包晶反应形成,并与Li₂O和Li₂CO₃分别形成共晶反应,共晶温度分别为400±3℃和612±3℃。在BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O体系中都没有观察到固溶体。用计算机程序分别对化合物4BaB₂O₄·Li₂B₂O₄和2BaB₂O₄·3Li₂O的X射线粉末衍射图案进行了指标化,其结果:4BaB₂O₄·Li₂B₂O₄的空间群为Pmma,a=13.033?,b=14.630?,c=4.247?,每个单胞包含两个化合式单位;2BaB₂O₄·3Li₂O的空间群为Pmmm,a=4.814?,b=9.897?,c=11.523?,每个单胞也含有两个化合式单位。 关键词：     

Al2O3衬底MgB2超薄膜的研究

我们利用混合物理化学气相沉积法(Hybrid physical-chemical vapor deposition简称为HPCVD)在(000l)Al2O3衬底上制备了系列干净的MgB2超薄膜,并通过R-T测量、SEM测量、M-T测量、XRD测量对它们进行了表征,探究了其超导电磁性能和薄膜的生长机制.其中的7.5nm厚的MgB2超薄膜为已报导的蓝宝石衬底上生长的性能最高的超薄膜.     

Investigation of structural,physical and optical properties of CeO2–Bi2O3–B2O3 glasses

xCeO₂–30Bi₂O₃–(70−x) B₂O₃ glasses are synthesized by using the melt quench technique. A number of studies such as XRD, density, molar volume, optical band gap, refractive index and FTIR spectroscopy are employed to characterize the glasses. The band gap decreases from 2.15 to 1.61 eV, refractive index increases from 2.67 to 2.93 and density increases from 4.151 to 4.633 g/cm³. The decrease in band gap with CeO₂ doping approaches the semiconductor behavior. FTIR spectroscopy reveals that incorporation of CeO₂ into glass network helps to convert the structural units of [BO₃] into [BO₄] and results in Bi–O bond vibration of [BiO₆].     

Mn3O4包覆对LiNi0.5Mn1.5O4正极材料界面电化学性能的提高

本文采用化学湿磨法,首次将金属氧化物Mn₃O₄包覆于LiNi_0.5Mn_1.5O₄颗粒表面,使得电极材料的电子电导率从1.53×10^-7 S/cm 提高到3.15×10^-5 S/cm. 电化学测试结果表明Mn₃O₄包覆大大提高LiNi_0.5Mn_1.5O₄正极材料的倍率性能和高温循环稳定性. 最佳包覆样品为2.6wt% Mn₃O₄包覆的LiNi_0.5Mn_1.5O₄,在10 C倍率下具有108 mAh/g的高放电容并且在55 °C下100次循环后仍有78%的容量保持率,远大于未包覆样品67%的容量保持率.     

(Ce0.8Sm0.2O2-δ/Y2O3:ZrO2)N超晶格电解质薄膜的制备及表征

采用脉冲激光沉积技术(PLD), 在MgO单晶基底上, 依次沉积氧化钐掺杂的氧化铈(Ce_0.8Sm_0.2O_2-δ, SDC)和钇稳定氧化锆(8 mol%Y₂O₃:ZrO₂, YSZ)制备了五种(SDC/YSZ)_N (N=3, 5, 10, 20, 30) 超晶格电解质薄膜. 利用X射线衍射(XRD)、高分辨透射电子显微镜(HR-TEM)和交流阻抗对其形貌、相结构和电学性能进行了表征. 结果显示, (SDC/YSZ)_N超晶格电解质薄膜之间形成了明显的界面和较好的超晶格结构; 薄膜表面颗粒生长均匀、致密、平滑, 在薄膜的界面处没有元素相互扩散也未出现裂纹, 外延生长良好; 电导率随着(SDC/YSZ)_N超晶格电解质界面数的增加而增加, 而活化能则随之减少, 是较为理想的低温固体氧化物燃料电池电解质.     

YBa2Cu3O7－δ/SrNb0.01Ti0.99O3 p-n结的制备及其特性

采用脉冲激光沉积技术，在n型SrNb001Ti099O3(SNTO)单晶基片上生长p型YBa2Cu3O7-δ(YBCO)薄膜，制备出YBCO/SNTO p n结.YBCO薄膜是高度c轴织构的超导薄膜，且具有良好的超导电性.YBCO/SNTO p n结具有较好的整流特性和很好的温度与磁场稳定性. 关键词： YBa2Cu3O7-δ SrNb001Ti099O3 p n结