Ba2RETaO6(RE= Pr, Nd, Eu, and Dy), A Group of Chemically Stable Substrates for YBa2Cu3O7−δFilms

✍ Scribed by T.G.N. Babu; J. Koshy

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 271 KB
• Volume: 126
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1996.0330

✦ Synopsis

ductors under severe heat treatment and have moderately A group of complex perovskites, Ba 2 RE TaO 6 (where RE ‫؍‬ low dielectric constant and loss factor. Here, we report the Pr, Nd, Eu, and Dy) has been synthesised and sintered as single synthesis, characterization, and sintering of Ba 2 RE TaO 6 phase materials with high sintered density and stability by solid ceramics and their suitability as potential substrates for state reaction. All compounds were found to be isostructural, YBCO superconductor films.

having a complex cubic perovskite crystal structure of the general formula A 2 (BB)O 6 with the lattice constant value in the range from 8.55 to 8.44 A ˚. The values of the dielectric constant 2. EXPERIMENTAL and the loss factor for these materials are in the range suitable for the use as substrates for microwave applications of super-

The polycrystalline Ba 2 RE TaO 6 (where RE ϭ Pr, Nd, conductor films. The YBa 2 Cu 3 O 7؊␦ superconductor showed no Eu, and Dy) compounds were synthesized by mixing stoichemical reaction with Ba 2 RETaO 6 ceramics even when they chiometric amounts of high purity (99.9%) rare earth oxwere mixed in composites of the form 80 vol% YBCO-20 vol% ides, BaCO 3 and Ta 2 O 5 , followed by calcination of pressed Ba 2 RETaO 6 and processed in air up to 1223 K. All the compos-pellets at 1373-1423 K for 50 h with three intermediate ites showed a T c(o) of 92 K. The YBCO thick films fabricated grindings. The calcined materials, after a thorough grindon polycrystalline Ba 2 RETaO 6 specimens by dip coating and ing, were pressed uniaxially at a pressure of 5 ton/cm 2 in partial melting techniques showed (00l ) orientation with T c(o) the form of disks with dimensions 13 mm in diameter and of 92 K.