温度勾配下加熱による高温超電導性YBaCuO系酸化物の結晶配向性制御と活性化焼結

概要

論文の詳細を見る
Possibility of grain orientation controlling and activated sintering by thermal diffusion treatment (named heterogeneous sintering) was studied for the superconductive Y1Ba2Cu3Oy ceramics, starting raw materials were mixed powder compacts of Y2O3, BaCO3 and CuO. Heating rate, upper surface temperature, effective temperature gradient, sintering time and cooling rate were approximately, 2K/s, 1240K, 10K/s, 1.8 ks18 ks and 1.4K/s at 750K, respectively; (1) The grains in Y1Ba2Cu3Oy ceramics produced by thermal diffusion treatment were found to be oriented with the c-axis along a heat flow direction, showing a fairly well-oriented grain structure. (2) Clear differences in temperature dependent electric resistivity between heterogeneously and homogeneously (conventionally) sintered ceramics were recognized as; Critical temperature (Tconset)of superconductivity for the sample which was hetrogeneously sintered for 1.8 ks and cooled at 1.4 K/s in air was both 90 K for the A-B plane (perpendicular to a heat flow direction) and the C-plane (parallel to a heat flow direction). Contrary to this, Tconset for the sample which was homogeneously sintered under the same condition as the above has never appeared in the temperature range down to 77K of liquid nitrogen temperature.
社団法人粉体粉末冶金協会の論文