Optimizing the physical characterizations of orthoferrites to be used as pressure and gamma sensor

The magnetic and electrical properties of a series of orthoferrites: R0.7Ca0.3FeO3, R = La, Dy, Y, Er and Gd, were investigated from room temperature up to about 800 K. All samples were antiferromagnetic with a weak ferromagnetic component due to small canting of the Fe3+ moments. The correlation between magnetic transition and structural distortion is discussed on the basis of the variation of the Néel temperature as a function of the tolerance factor. The ac resistivity data at different frequencies from 100 kHz to 5 MHz is presented and discussed in view of structural characterization. The effect of γ-irradiation on both ac resistivity and magnetic susceptibility is investigated. Also, the influence of mechanical pressure on the dc resistivity was studied.