High-Pressure Synthesis of Fully Occupied Tetragonal and Cubic Tungsten Bronze Oxides

Angewandte Chemie - International Edition

4 years ago

High-Pressure Synthesis of Fully Occupied Tetragonal and Cubic Tungsten Bronze Oxides

Taito Murakami, Cédric Tassel, Hiroshi Kageyama, Yoshihiro Goto, Yuya Ikeuchi, Hiroshi Takatsu

A high-pressure reaction yielded the fully occupied tetragonal tungsten bronze K3W5O15 (K0.6WO3). The terminal phase shows an unusual transport property featuring slightly negative temperature-dependence in resistivity (dρ/dT<0) and a large Wilson ratio of RW=3.2. Such anomalous metallic behavior possibly arises from the low-dimensional electronic structure with a van Hove singularity at the Fermi level and/or from enhanced magnetic fluctuations by geometrical frustration of the tungsten sublattice. The asymmetric nature of the tetragonal tungsten bronze KxWO3-K0.6−yBayWO3 phase diagram implies that superconductivity for x≤0.45 originates from the lattice instability because of potassium deficiency. A cubic perovskite KWO3 phase was also identified as a line phase—in marked contrast to NaxWO3 and LixWO3 with varying quantities of x (<1). This study presents a versatile method by which the solubility limit of tungsten bronze oxides can be extended. A full house: A tetragonal tungsten bronze KxWO3 featuring fully occupied potassium ion sites (x=0.6) was accessed by a high-pressure reaction. K3W5O15 (K0.6WO3) fails to exhibit charge ordering despite strong electron–electron correlations, but shows an anomalous metallic behavior attributed to the frustrated geometry of the tungsten sublattice.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201701732