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Barium Rare‐Earth Hafnates: Synthesis, Characterization, and Potential Use as Substrates for YBa 2 Cu 3 O 7 ‐delta Superconductor
Author(s) -
John Asha Mary,
Jose Rajan,
Kurian Jose,
Sajith Poo Koodan,
Koshy Jacob
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb01933.x
Subject(s) - electrical resistivity and conductivity , materials science , superconductivity , barium , isostructural , analytical chemistry (journal) , crystallite , mineralogy , transition temperature , high temperature superconductivity , crystallography , crystal structure , condensed matter physics , chemistry , metallurgy , physics , engineering , chromatography , electrical engineering
A new group of complex perovskites Ba 2 REHfO 5.5 (where RE = La, Pr, Nd, and Eu) has been synthesized and sintered as single‐phase materials with high sintered density and stability using a solid‐state reaction method for the first time. The structure of Ba 2 REHfO 5.5 has been studied by X‐ray diffactometry (XRD) and all of the perovskites are isostructural and have a cubic structure. The dielectric constant and loss factor values of these materials are in a range suitable for their use as substrates for YBa 2 Cu 3 O 7‐delta superconductors. XRD and resistivity measurements show that there is no detectable reaction between YBa 2 Cu 3 O 7‐delta and Ba 2 REHfO 5.5 , even when the two substances are mixed thoroughly and sintered at 950°C for 15 h. The addition of Ba 2 REHfO 5.5 up to 20 vol% in YBa 2 Cu 3 O 7‐delta ‐Ba 2 REHfO 5.5 composite shows no detrimental effect on the superconducting transition temperature of YBa 2 Cu 3 O 7‐delta . Thick films of YBa 2 Cu 3 O 7‐delta fabricated on polycrystalline Ba 2 REHfO 5.5 substrate have a superconducting zero resistivity transition of 92 K, indicating the suitability of these new materials as substrates for YBa 2 Cu 3 O 7‐delta films.