This article is cited in 9 papers

Phase transitions

Features of the Jahn-Teller transition in Ni$_{1-x}$Co$_x$Cr$_2$O$_4$ solid solutions

A. S. Mikheikin^ab, D. Yu. Chernyshov^b, A. A. Bush^c, A. S. Prokhorov^de, Yu. I. Yuzyuk^a, V. P. Dmitriev<sup>b

a</sup> Southern Federal University, Rostov-on-Don
^b Swiss-Norwegian Beamlines at the European Synchrotron Radiation Facility, Grenoble, France
^c MIREA — Russian Technological University, Moscow
^d Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow
^e Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region

Abstract: The structure of Ni$_{1-x}$Co$_x$Cr$_2$O$_4$ solid solutions has been investigated by synchrotron X-ray powder diffraction in the temperature range of 90–350 K for compositions $x$ = 0, 0.005, 0.01, 0.015, 0.02, 0.1, 0.5, and 0.8, and their structures have been refined using the Rietveld analysis. The $T-x$ phase diagram for solid solutions in the studied range of temperatures and concentrations has been constructed based on the obtained data. The revealed structural phase transitions have been explained from the viewpoint of the crystal field theory and the Jahn–Teller cooperative effect. Distortions of polyhedra, which are the cause of the structural phase transition, have been evaluated. The applicability of the Landau phenomenological theory and the possibility of using the magnitude of spontaneous strains as the order parameter have been discussed.

Received: 03.10.2013

 English version: Physics of the Solid State, 2014, 56:4, 785–791

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