摘要
报导了用熔融定向凝固工艺制备的有织构YBCO超导体的微结构变化及其特性。将YBCO坯料加热到1050—1120℃,分解成Y_2BaCuO_5(211)和液相(Ba-Cu-O),然后在50℃/cm的温度梯度下,慢速移动样品重新合成YBCO超导体。X光衍射结果证实,熔融样品具有较强的c轴织构。扫描电镜观察表明,熔融后晶粒形貌发生了显著变化:YBCO晶粒由原烧结块材的随机排列变为一致取向或局部取向排列的片状组织。熔融样品的J_c(77K,0T,>10000 A/cm^2)值比烧结块材J_c(750A/cm^2)值提高近两个数量级,在1T(H⊥I_c)下,J_c值达5790 A/cm^2。而且J_c随磁场增加而下降的趋势变平缓。
The microstructure changes and the properties of the YBCO superconductors with the texture prepared by a directional melt solidification process are reported in this paper. The YBCO blank heated to 1050～1120℃ will be decomposed into Y_2BaCuO_5(211) phase and liquid phase (Ba-Cu-O), but YBCO(123) superconductor will be recomposed when the sample is slowly translated at the temperature gradient of approximately 50℃/cm. X ray diffraction pattern confirms that the YBCO phase of the melted samples possesses a strong c axis texture. SEM observation reveals that the morphology of the YBCO grain in the melted samples changes significantly, the YBCO grain of melted samples will transform from random aligned into all or partial orientation aligned and form plate-like crystal structure after melting. The J_c (77K, 0T, >10000A/cm^2) value of the melted samples has increased approximately two orders of magnitude than that of the sintered bulk materials. At 77K, 1T, the J_c value reaches 5790A/cm^2 and the trend of the degradation of J_c as the increase of the magnetic field is slow down.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
1992年第1期25-29,共5页
Rare Metal Materials and Engineering
