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구연산법에 의한 고온 산화물 초전도체 YBa2Cu3O7-x의 제조에서 pH와 소결온도의 영향
The Effects of pH and Sintering Temperature in Preparing High-Tc Oxide Superconductor YBa2Cu3O7-x by Amorphous Citrate Process
HWAHAK KONGHAK, August 1990, 28(4), 444-450(7), NONE
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Abstract
YBa2Cu3O7-x 초전도체를 구연산법을 이용하여 제조하였으며, 천이온도에 대한 pH와 소결온도의 영향을 조사하였다. 투명한 암청색 sol을 pH=5.5-6.5, 양이온몰비 Y:Ba:Cu=1:2:3으로 혼합된 질산 수용액으로부터 얻었으며, 거의 단일상의 YBa2Cu3O7-x 초전도체를 소결온도 900℃, 소결시간 2시간 공기분위기 하에서 얻었다. YBa2Cu3O7-x 초전도체 제조시 pH는 천이온도에 거의 영향을 미치지 않았으며 최적의 소결온도는 900-950℃로 그 때의 천이온도는 94-97K였다. 동의 평균 원자가와 산소함량이 증가할수록 천이온도는 높아졌으며, pH=6.05, 소결온도 950℃에서 천이온도 97K로 가장 높게 나타났다. 박막제조의 기초연구로서 YBa2Cu3O7-x와 ZrO2, SiO2, γ-Al2O3, MgO의 반응성을 조사하였는데, MgO는 다른 산화물과는 달리 YBa2Cu3O7-X중의 Ba과 반응하지 않아 초전도 박막제조의 substrate로 사용할 수 있을 것으로 기대된다.
YBa2Cu3O7-x superconductor was prepared by amorphous citrate process and the effects of pH and sin-tering termperature on transition temperature were examined. Kark blue transparent sol was obtained from the nitrate solution which has cation mole ratio of Y:Ba:Cu=1:2:3 and initial pH of the solution in the range of 5.5-6.5. YBa2Cu3O7-x powders of nearly pure phase were prepared by sintering the citrate precursor in air atmosphere at 900℃ for 2 hours. In preparing YBa2Cu3O7-x superconductor, it was found that pH has almost no influence on transi-tion temperature and that optimum sintering temperature was in the range from 900 to 950℃. Its sintering tempera-ture was in the range from 900 to 950℃. Its sintering temperature was between 94 to 97K. As the aberage copper valence and the content of oxygen were increased, the transition temperature was increased. The highest transition temperature attained at pH of 6.05 and sintering temperature of 950℃ was 97K. As basic work for manufacturing thin film of superconductor, the reactions between YBa2Cu3O7-x and ZrO2, SiO2, γ-Al2O3, MgO were tested as substrate. Among them, MgO was not reacted with Ba in YBa2Cu3O7-x.
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