Low-Temperature Synthesis of Superconductor Ba_1-<em>x</em>K_<em>x</em>BiO₃

Abstract

was synthesized using a topotactic reaction, which involves a conventional solidstate synthesis of pure BaBiO3, using BaCO3 and Bi2O3 as the raw materials, and subsequent treatment of BaBiO3 in a KOH flux at low temperature. All samples were characterized using X-ray diffraction (XRD) and magnetic susceptibility measurements. The XRD patterns show that there is no apparent impurity in the obtained Ba1-xKxBiO3 samples, and all the diffraction data can be indexed using a pseudo-cubic cell. All the samples showed superconductivity, and the highest superconducting transition temperature (Tc) was 30.6 K. The influences of the reaction time and the ratio of the precursor to the molten salts on the transition temperature were investigated. The best reaction conditions were treatment at 450°C for 4 h, with BaBiO3:KOH:KF mass ratio of 1:5:2.5.