The Effect of Ionic Radius Difference of RE3+and Ba2+on the Shock Synthesis of REBa2Cu3Oy(RE=Y, Eu, La)

• Published in: Journal of solid state chemistry Vol. 136; no. 1; pp. 74 - 78
• Main Authors: Hikosaka, Hideaki, Kusaba, Keiji, Fukuoka, Kiyoto, Kikuchi, Masae, Syono, Yasuhiko
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15-02-1998; Elsevier
• Subjects: Chemistry; Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...); Exact sciences and technology; Inorganic chemistry and origins of life; Preparations and properties; Compression; Europium Oxides; Transition metal Compounds; Lanthanum Oxides; Ionic radius; Experimental study; Mechanical activation; Alkaline earth metal Compounds; Shock wave; Copper Oxides; Barium Oxides; Quaternary compound; Yttrium Oxides; Chemical preparation; Lanthanide Compounds; High temperature superconductor
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1997.7658

Shock-synthesis experiments of REBa2Cu3Oy(RE=Y, Eu, and La) were carried out for the mixture of component oxides as starting materials using a 25 mm-bore propellant gun. Both tetragonal EuBa2Cu3Oywithc/a=3.00 and cubic LaBa2Cu3Oywere successfully synthesized by shock compression, but YBa2Cu3Oywas synthesized only partly. The optimum condition for obtaining maximum yield of shock-synthesized EuBa2Cu3Oyand LaBa2Cu3Oywas shock compression of the starting materials with 40% porosity to 30 GPa. La1+xBa2−xCu3Oycould also be synthesized, but Eu1+xBa2−xCu3Oycould not. Shock-synthesized EuBa2Cu3Oyand LaBa2Cu3Oywere in a metastable phase in which RE3+and Ba2+were not ordered perfectly; they converted to the phase synthesized by conventional solid state reaction when annealed above 900°C. Only after annealing above 900°C, followed by oxidation at 400°C, did EuBa2Cu3Oyexhibit superconductivity withTc≒71 K. These results suggest that shock synthesis of REBa2Cu3Oybecomes easier with a decrease in the difference between ionic radii of RE3+and Ba2+.