Synthesis and Thermostructural Studies of a CuFe_1−<i>x</i>Cr_<i>x</i>O₂ Delafossite Solid Solution with 0 ≤ <i>x</i> ≤ 1

Abstract

In this work, different CuFe(1-x)Cr(x)O(2) compositions with 0 <or= x <or= 1 were prepared by a standard solid-state reaction. These oxides crystallize with the delafossite structure. The phase stability and thermal behavior of the complete CuFe(1-x)Cr(x)O(2) solid solution was studied by thermogravimetric analysis and high-temperature X-ray diffraction experiments under an air atmosphere up to 1000 degrees C. For x = 0, CuFeO(2) is oxidized into the spinel (CuFe(2)O(4)) and copper monoxide (CuO) phases, whereas for x = 1, CuCrO(2) is thermally stable. For all of the intermediate compositions (0 < x < 1), complex oxidation, reduction, and phase transitions between delafossite and spinel have been observed. chromium tends to stabilize the stoichiometric delafossite phase, while iron favors the delafossite-to-spinel phase transition.