Non-cubic layered structure of Ba(1-x)K(x)BiO3 superconductor

TL;DR

This study reveals that Ba(1-x)K(x)BiO3 superconductors have a non-cubic layered structure with an ordered arrangement of barium and potassium, challenging previous crystallographic assumptions and linking them more closely to cuprate superconductors.

Contribution

The paper uncovers the non-cubic layered and non-centrosymmetric structure of Ba(1-x)K(x)BiO3, providing new insights into its crystallography and relation to high-Tc superconductors.

Findings

The structure is non-cubic and layered.

The structure is non-centrosymmetric.

Contains an ordered arrangement of Ba and K.

Abstract

Bismuthate superconductor Ba(1-x)K(x)BiO3 (x=0.27-0.49, Tc=25-32K) grown by an electrolysis technique was studied by electron diffraction and high-resolution electron microscopy. The crystalline structure thereof has been found to be non-cubic, of the layered nature, and non-centrosymmetric, with the lattice parameters a ~ ap, c ~ 2ap (ap is a simple cubic perovskite cell parameter) containing an ordered arrangement of barium and potassium. The evidence for the layered nature of the bismuthate superconductor removes the principal crystallographic contradiction between bismuthate and cuprate high-Tc superconductors.