高T_c陶瓷中非超导相的EPMA研究

EPMA Study on Non-Superconducting Phases of High T_c Ceramics

用 EPMA 的背散射电子像和相的元素分析发现,在 Ag-EuBa_2Cu_(3-x)O_7高 T_c 陶瓷中存在富 Ag 贫Cu 和无 Eu 二种非超导相,在 Ag-YBa_2Cu_(3-x)O_7中存在富 Ag 贫 Cu,富 Y 贫 Cu 和无 Y 富 Cu 三种非超导相,减少非超导相和气孔的数量是提高超导氧化物陶瓷临界电流密度的重要途径。对高 T_(?)陶瓷显微结构的观察度现,T_c 对显微结构因素不敏感,T_c 相同的超导陶瓷显微结构可有明显差异;断裂方式与烧结温度有关。

Some non-superconducting phases have been found in polished section of thesintered Ag-EuBa_2Cu_((?)-x)O_7 and Ag-YBa_2Cu_(3-x)O_7 superconductors by backscatteredelectron composition image and elements analysis of EPMA.There are two non-superconducting phases in Ag-EuBa_2Cu_(3-x)O_7:Ag-rich and Cu-poor phase,and Euabsent phase;and there are three non-superconducting phases in Ag-YBa_2Cu_(3-x)O_7:Ag-rich and Cu-poor phase,Y-rich and Cu-poor phase,and no Y and Cu-richphase.The amount of non-superconducting phase and porosity can influence thecritical current density of superconducting ceramies greatly.We have found that T_c is not sensitive to the microstructure of high T_cceramics,and the fracture type of the sample is concerned with its sintering tem-perature.