Elastic and thermal properties of the layered compound (CH 3 NH 3 ) 2 FeCl 4
1982; IOP Publishing; Volume: 15; Issue: 14 Linguagem: Inglês
10.1088/0022-3719/15/14/011
ISSN1747-3802
AutoresT. Goto, M. Yoshizawa, Akira Tamaki, T. Fujimura,
Tópico(s)Perovskite Materials and Applications
ResumoSeveral elastic constants of the perovskite-type layer-structure compound (CH3NH3)2FeCl4 have been measured. The anomaly of the C66 mode and the lambda -type heat capacity near the structural phase transition from the tetragonal high-temperature phase to the orthorhombic room-temperature phase gave the critical exponents for heat capacity alpha = alpha '=0, the amplitude ratio A/A'=1.01 and the crossover exponent phi =1.21. This set of exponents confirms the results of the renormalisation group methods for the three-dimensional XY model (n=2, d=3). The elastic soft mode C66 in the tetragonal low-temperature phase has been observed. The authors surveyed the somewhat questionable orthorhombic low-temperature phase under hydrostatic pressure up to 6 kbar.
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