Crystal structure, electro conductivity and thermal expansion coefficient of Sr1-xGdxFe12-xCoxO19 (0 ≤ x ≤ 0,5) ferrites

Abstract

Sr_1-xGd_xFe_12-xCo_xO₁₉ (x = 0; 0,1; 0,2; 0,3; 0,4; 0,5) ferrites have been prepared by solid-state method in air at 1473 K. XRD has shown that samples with x ≥ 0,2 contained not only main phase with the magnetplumbite structure, but also the a-Fe₂O₃ and Gd₃Fe₅O₁₂ phases. There were GdFeO₃ and CoFe₂O₄ phases present in the samples with x = 0,3; 0,4; 0,5, samples with x = 0,4; 0,5 also contained Gd₂O₃ phase. It has been found that the conductivity activation energy for Sr_1-xGd_xFe_12-xCo_xO₁₉ (x = 0-0,4) ferrites at temperatures above the T_frac 1næ dependence of T^-1 is 0,13-0,18 eV higher than the activation energy in the temperature range below the T_frac. The coefficient of linear thermal expansion (a) for Sr_1-xSmGd_xFe_12-xCo_xO₁₉ ferrites changes slightly in the x range from 1,13^.10^-5 K^-1 to 1,27^.10^-5 K^-1.