MOD法制备YBa2Cu3O7—x超导薄膜

用Ｙ、Ｂａ、Ｃｕ的三氟乙酸盐溶液，通过ＭＯＤ法在ＳｒＴｉＯ３（１００）衬底上成功地制得了黑色的、表面光滑的ＹＢＣＯ超导薄膜。研究了两种理想的成膜烧结工艺，对膜进行了物相研究。结果表明：在８５０℃，潮湿氧气氛中烧结的薄膜具有一定的择优取向；而在７５０℃，潮湿的低氧气氛中烧结的薄膜则具有高度的ｃ轴织构，前者的Ｔｃ（ｏｎｓｅ）≈９０Ｋ，Ｔｃ０≈７９Ｋ，较低的氧分压似乎有利于ｃ轴结构。     

YBa2Cu3O7—x—Ag界面与表面的研究

使用XRD,SEM-EDX和LAS-3000联合谱仪研究了YBCO-Ag界面与表面。结果表明,YBCO体内掺0.4 mol Ag对123结构无影响.Ag偏聚在晶界上使晶粒间变得明显清晰;AES分析指出Ag偏聚在表面上,降低了YBCO-金属导线的接触电阻.实验还证实,不论掺入的原料是单质(Ag粉)还是化合物(Ag_2O,AgNO_3),经高温退火处理,Ag总是以单质形态固溶和偏聚在晶界及表面上,由于Ag的室温电阻率很小,有利于增强超导颗粒间的连通性。     

STUDY OF INTERFACES AND SURFACES OF YBa_2Cu_3O_(7-x)-Ag

Interfaces and surfaces of YBa_2Cu_3O_(7-x)(YBCO)-Ag have been studied by SEM-EDXand AES.No effect of Ag on 123 structure in X-ray diffraction pattern was observedfor 0.4 mol Ag doped YBCO.AES analysis indicated that Ag segregated on surfaceof YBCO and resulted in decrease of YBCO-metal lead resistance.In addition,solutionand segregation of Ag as elemental state were often appeared on interfaces and surfacesof high temperature annealed YBCO,whether elemental Ag or compound Ag_2O andAgNO_3 adopted as doping material.     

YBa_2Cu_3O_7能隙及低温物性的第一原理计算

采用密度泛函理论（DFT）中的BLYP和ROBLYP交换．相关泛函,基于YBa2Cu3O7单晶胞即39个原子组成的团簇模型,计算了其能隙、磁化系数、电子比热及比热系数随温度的变化关系,并分析了在不同温度下其最高占据态的分子轨道图。结果表明,YBa2Cu3O7存在3个特征温度Tc、T^＊和T^0,在正常态存在赝能隙,并且其超导能隙和赝能隙均具有d波对称性。     

{001}LaAlO_3衬底上沉积YBa_2Cu_3O_（7-x）薄膜的HRXRD研究

采用脉冲激光沉积技术（PLD）在{001}LaAlO3（LAO）衬底上生长YBa2Cu3O7-x（YBCO）薄膜,并通过极图、摇摆曲线以及倒易空间图谱等高分辨X射线衍射技术（HRXRD）对其微结构进行表征。结果表明,YBCO薄膜的晶粒取向主要为{001}YBCO//{001}LAO,〈100〉YBCO//〈100〉LAO,但还有2%的{001}YBCO//{001}LAO,〈110〉YBCO//〈100〉LAO取向。摇摆曲线结果表明,YBCO的面外取向有一定的漫散（宽度为0.75°）;薄膜面内存在90°±0.65°〈110〉孪晶畴结构,主要是由四方到正交的相变过程中较大的局部应力以及〈100〉和〈010〉方向应力差异引起的。     

THE EFFECT OF SUBZERO TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Y_2O_3-ZrO_2 CERAMIC

The effect of subzero treatment on the microstructure and mechanical properites of Y_2O_3-ZrO_2 ceramic have been investigated by TEM,X-ray diffraction and test of mechanicalproperties.It was shown that the microstructre of 3Y-PSZ after subzero treatment byliquid nitrogen exhibits very long and parallel laths of m-phase and some microcracksaround the larger and finer lath of m-phase may be discovered.Suitable subzero treatmentcan improve the strength and toughness of Y-PSZ efficiently because of decreasing thestability of t-phase and incresing the amount of t-m transformation when exerting astress.However,when the time of subzero treatment exceeds,the over aging effect mayarise.which can decrease the strength and toughness of the material.     

冷处理对Y2O3—ZrO2陶瓷的显微结构和力学性能的影响

通过TEM显微结构分析,XRD相分析和力学性能测试,研究了冷处理对Y_2O_3—ZrO_2、陶瓷的显微结构与力学性能的影响。结果表明:Y_2O_3—ZrO_2(3Y—PSZ)陶瓷经液氮处理后、产生平行排列的m相板条,同时,m相板条周围出现微裂纹,适当的冷处理降低了t相的稳定性,导致施加应力时t→m相变量增加,可以有效地改善Y_2O_3-ZrO_2陶瓷的强度和韧性,但冷处理时间过长,则出现过时效现象。