Cooperative Jahn-Teller Phase Transition in the Nickel-Zinc-Chromite System

Autor:	B. Lüthi, M. E. Mullen, Yoshihiro Kino
Rok vydání:	1972
Předmět:	Phase transition Materials science Condensed matter physics Jahn–Teller effect Analytical chemistry General Physics and Astronomy Nickel zinc Soft modes Chromite First order Thermal expansion Ion
Zdroj:	Journal of the Physical Society of Japan. 33:687-697
ISSN:	1347-4073 0031-9015
DOI:	10.1143/jpsj.33.687
Popis:	Results of thermal expansion and sound velocity measurements are presented for the Nickel-Zinc-Chromite system (Ni x Zn 1- x Cr 2 O 4 ). It is found that for x >0.6 this system exhibits a cooperative Jahn-Teller phase transition which occurs at a temperature T a higher than the magnetic phase transition at T N . Both transitions at T a and T N are of first order. The temperature dependence of the soft mode c 11 – c 12 could only be measured for T > T a . From its temperature dependence, we conclude that the electronic state of the Ni 2+ ion couples predominantly to the macroscopic strains. A comparison between our sound velocity data and the Kataoka-Kanamori theory gives only fair agreement for T > T a . It is found that the low temperature magnetic phase transition influences the cooperative J-T-transition considerably.
Databáze:	OpenAIRE
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