YBCO熔融织构准单晶中的进氧和脱氧扩散研究  

The oxygen in-and out-diffusion behavior in melt-textured YBCO measured by thermogravimetry

作　　者：张玉龙[1] 姚忻[1,2] 张宏[3] 金燕苹[4] 

机构地区：[1]上海交通大学物理系 [2]上海交通大学金属基复合材料国家重点实验室,上海200030 [3]中国科学院上海微系统与信息技术研究所 [4]上海交通大学金属基复合材料国家重点实验室

出　　处：《物理学报》2005年第7期3380-3385,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50272038);博士点科研基金(批准号:20030248010);科技部项目(批准号:2002AA306261;G1999064606)资助的课题.~~

摘　　要：采用热重法研究了YBCO熔融织构准单晶中氧的化学扩散过程.与以往的实验不同,采用固定氧偏压变化温度的方法获得氧浓度梯度.拟合实验所得重量等温弛豫曲线可知,在375—600℃温区内,熔融织构准单晶的氧化学扩散系数比单晶体高出约50%,但都约为10-10cm2s-1,激活能为～1eV.对YBCO熔融织构准单晶中的进氧和脱氧研究表明两者具有相同的速率,证实实验过程中环境氧分压的改变会导致进氧和脱氧过程不一致.The chemical oxygen in- and out-diffusion in melt-textured YBa2Cu3O7-delta (YBCO) is investigated by thermogravimetry. The weight relaxations resulting from the sudden change of temperature at a fixed oxygen partial pressure of 0.33 x 10(5) Pa are recorded. By fitting the isothermal curves, the chemical diffusion coefficients at 375-600 degrees C are determined. It is found that the resultant numerical values for melt-textured YBCO are larger than that of crushed single crystal YBCO obtained in our previous study by about 50%, whereas all of them are of the order of 10(-10) cm(2) s(-1). The activation energies for both samples are estimated as similar to 1eV. It is believed that those values represent the nature of the lattice diffusion. The oxygen diffusion in melt-textured-grown-YBCO is attributed to the YBCO matrix and the micro-cracks are responsible for the huge diffusion coefficients. Moreover, the same kinetics of in- and out-diffusion is confirmed to be intrinsic, and it suggests that the different in- and out-diffusion coefficients measured in other works are controlled by the large concentration gradient and the shell effect.

关 键 词：熔融织构 YBCO 准单晶 氧扩散 扩散过程 浓度梯度 扩散系数 实验过程 热重法 600 激活能 氧分压 化学 脱氧 

分 类 号：O511[理学—低温物理]