Preparation and Superconductivity of Dy-Sr-Ba-Cu-O

• Main Authors: Jean Yeong-Shing, 簡永興
• Other Authors: Wang Chii-Ming
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/80274737564369803752

碩士 === 淡江大學 === 化學學系 === 82 === A series of single phase Dy-Sr-Ba-Cu-O superconductors (abbreviated as Dy series) with tetragonal triple-pervoskite structure is prepared by either the solid state neaction or the citrate precursor method. Reactant mixtures are calcined at 900degreeC-950degreeC for 4hour, sintered at 900degreeC for 6hour in static air or dioxide, and annealed at 500degreeC for 8hour in folwing dioxide atmosphere. The resultion materials are then examined by the powder X-ray diffraction and thermal analysis to determined their phase purity. The solubility limit for Dy series is 0.6.ltoreq.X.ltoreq.1.0. Unit cell parameters, such as a axes and all volumes, Decreases monotonically with increase of Sr substitution due to the smaller Sr2+ ionic radius compared with Ba2+. In order th have superconductivity for the Dy series, unit cell a axes and hole concentrations(p) must be in between 3.823-3.844.ANG. and 0.1511-0.2313 respectivity. Moreover the critical temperature(Tc) increases with increasing X ans hole concentration. The highest Tc observed is 77K at X=1.0 with p=0.2313.