PHASE TRANSITION OF CaFeO2.5 AT HIGH TEMPERATURE

Labii, T; Ceretti, M; Boubertakh, A; Paulus, W; Hamamda, S

Sciences & technologie. A, sciences exactes
Volume 0, Numéro 34, Pages 29-34
2011-12-31

Phase Transition Of Cafeo2.5 At High Temperature

Authors : Labii T . Ceretti M . Boubertakh A . Paulus W . Hamamda S .

Abstract

The numerous studies conducted on the structure of CaFeO2.5 showed that the material undergoes a series of transformations based on temperature. The first one appears around 700 K and indicates the evolution of the phasemagnetic material to a paramagnetic phase. At about 970 K the structure of CaFeO2.5 changes from rhombohedral to centered structure. Finally, around 1180 K it undergoes the transition to a structure that has been described as incommensurate modulated structure. We have observed the behavior of the material beyond this temperature by dilatometry, DSC and TGA. The tests conducted on a single crystal CaFeO2.5 confirm the changes already observed.For the first time there was a dilatometric anomaly (confirmed by DSC and TGA) at 1310 K. This anomaly appears only in the crystallographic direction b which should probably be a commensurate transformation of the material.