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

✍ Scribed by Hideaki Hikosaka; Keiji Kusaba; Kiyoto Fukuoka; Masae Kikuchi; Yasuhiko Syono

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 177 KB
• Volume: 136
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7658

✦ Synopsis

Shock-synthesis experiments of REBa 2 Cu 3 O y (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 EuBa 2 Cu 3 O y with c/a ‫؍‬ 3.00 and cubic LaBa 2 Cu 3 O y were successfully synthesized by shock compression, but YBa 2 Cu 3 O y was synthesized only partly. The optimum condition for obtaining maximum yield of shock-synthesized EuBa 2 Cu 3 O y and LaBa 2 Cu 3 O y was shock compression of the starting materials with 40% porosity to 30 GPa. La 1؉x Ba 2؊x Cu 3 O y could also be synthesized, but Eu 1؉x Ba 2؊x Cu 3 O y could not. Shock-synthesized EuBa 2 Cu 3 O y and LaBa 2 Cu 3 O y were in a metastable phase in which RE 3؉ and Ba 2؉ 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 EuBa 2 Cu 3 O y exhibit superconductivity with T c .

.71 K. These results suggest that shock synthesis of REBa 2 Cu 3 O y becomes easier with a decrease in the difference between ionic radii of RE 3؉ and Ba 2؉ .