X-ray absorption near edge spectroscopy of thermochromic phase transition in CuMoO4
I. Jonane1, A. Cintins1, A. Kalinko2, R. Chernikov3, and A. Kuzmin1
1Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., Riga LV-1063, Latvia
2Universität Paderborn, Naturwissenschaftliche Fakultät, Department Chemie, 100 Warburger Str., Paderborn 33098, Germany
3DESY Photon Science, 85 Notkestraße, Hamburg D-22607, Germany
Received October 26, 2017
Thermochromic phase transition was studied in CuMoO4 using the Cu and Mo K-edge x-ray absorption spectroscopy in the temperature range of 10–300 K. The hysteretic behavior has been evidenced from the temperature dependence of the pre-edge shoulder intensity at the Mo K-edge, indicating that the transition from brownish-red γ-CuMoO4 to green α-CuMoO4 occurs in the temperature range of 230–280 K upon heating, whereas the α-to-γ transition occurs between 200 and 120 K upon cooling. Such behavior of the pre-edge shoulder at the Mo K-edge correlates with the change of molybdenum coordination between distorted tetrahedral in α-CuMoO4 and distorted octahedral in γ-CuMoO4. This result has been supported by ab initio full-multiple-scattering x-ray absorption near edge structure (XANES) calculations.
PACS: 61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.;
Key words: x-ray absorption spectroscopy, CuMoO4, thermochromism, phase transition.
Published online: March 27, 2018