Study of the thermochromic phase transition in CuMo$_{1-x}$W$_x$O$_4$ solid solutions at the W L$_3$-edge by resonant X-ray emission spectroscopy

Abstract

Polycrystalline CuMo 1−x W x O 4 solid solutions were studied by resonant X-ray emission spectroscopy (RXES) at the W L 3 -edge to follow a variation of the tungsten local atomic and electronic structures across thermochromic phase transition as a function of sample composition and temperature. The experimental results were interpreted using ab initio calculations. The crystal-field splitting parameter ∆ for the 5d(W)-states was obtained from the analysis of the RXES plane and was used to evaluate the coordination of tungsten atoms.Temperature-dependent RXES measurements were successfully employed to determine the hysteretic behaviour of the structural phase transition between the α and γ phases in CuMo 1−x W x O 4 solid solutions on cooling and heating, even at low (x < 0.10) tungsten content. It was found that tungsten ions