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Barium Holmium Zirconate, A New Complex Perovskite Oxide: I, Synthesis, Characterization, and Potential Use as a Substrate for High‐Critical‐Temperature Superconductors
Author(s) -
Jose Rajan,
John Asha Mary,
Koshy Jacob
Publication year - 2002
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.1151-2916.2002.tb00469.x
Subject(s) - materials science , perovskite (structure) , zirconate , electrical resistivity and conductivity , barium , lattice constant , dielectric , mineralogy , sintering , oxide , analytical chemistry (journal) , ceramic , crystallography , diffraction , composite material , chemistry , metallurgy , optics , physics , optoelectronics , chromatography , electrical engineering , titanate , engineering
Barium holmium zirconate, a new complex perovskite ceramic oxide, has been synthesized through liquid‐phase sintering for the first time. The conventional solid‐state reaction method using constituent oxides and carbonates was found to be inadequate for the synthesis of Ba 2 HoZrO 5.5 material. During high‐temperature annealing, the development of stable BaZrO 3 and BaHoO 2.5 phases prevented the formation of Ba 2 HoZrO 5.5 as a single‐phase material, even at 1650°C. However, an addition of a small amount of CuO (1 wt%) in the reaction mixture has resulted in the formation of an ordered complex perovskite Ba 2 HoZrO 5.5 phase during the heating process. The structure of Ba 2 HoZrO 5.5 was studied by X‐ray diffraction and found to have a cubic perovskite structure with a lattice constant of a = 8.482 Å. Dielectric constant and loss factor values of Ba 2 HoZrO 5.5 are also in the range suitable for use as a substrate for microwave applications. The X‐ray diffraction and resistivity measurements have shown that there is no detectable chemical reaction in YBa 2 Cu 3 O 7−δ –Ba 2 HoZrO 5.5 and Bi(2212)–Ba 2 HoZrO 5.5 composites, even under extreme processing conditions. Dip‐coated and melt‐textured YBa 2 Cu 3 O 7−δ and Bi(2212) thick films developed on polycrystalline Ba 2 HoZrO 5.5 gave zero‐resistivity transition temperatures of T c (0) = 92 and 85 K, respectively.