Barium Holmium Zirconate, A New Complex Perovskite Oxide: I, Synthesis, Characterization, and Potential Use as a Substrate for High‐Critical‐Temperature Superconductors

Abstract

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 Ba2HoZrO5.5 material. During high‐temperature annealing, the development of stable BaZrO3 and BaHoO2.5 phases prevented the formation of Ba2HoZrO5.5 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 Ba2HoZrO5.5 phase during the heating process. The structure of Ba2HoZrO5.5 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 Ba2HoZrO5.5 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 YBa2Cu3O7−δ–Ba2HoZrO5.5 and Bi(2212)–Ba2HoZrO5.5 composites, even under extreme processing conditions. Dip‐coated and melt‐textured YBa2Cu3O7−δ and Bi(2212) thick films developed on polycrystalline Ba2HoZrO5.5 gave zero‐resistivity transition temperatures of Tc(0) = 92 and 85 K, respectively.