Structural phase transition and suppressed Griffiths-like phase induced by Sr2+-doping in LaCr0.5Mn0.5O3 compound

Abstract

We have investigated the influence of heat treatment and Sr-doping on the structural and magnetic properties of the LaCr0.5Mn0.5O3 compound produced by the modified combustion method using urea as fuel. It was shown that the undoped sample can be produced with heat treatment at a temperature as low as 300 °C. However, the addition of 10% Sr makes it difficult to be obtained at low temperatures, and hence, the desired phase was reached with a heat treatment above 800 °C. Moreover, the Sr-doping induced a structural phase transition from orthorhombic to rhombohedral, which is attributed to an increase of the ionic radius on the perovskite A-site. The observed deviation of the Curie-Weiss (C-W) law adjusted above the magnetic ordering temperature of the LaCr0.5Mn0.5O3 sample was attributed to the presence of Griffiths-like phase (GP) with Griffiths temperature at TG = 280 K, nevertheless, this deviation was suppressed with the Sr-doping. Finally, Sr-doping induces an increase of Cr4+ and Mn4+ valence states, enabling the existence of more double-exchange interactions, which is responsible for the increase of the magnetization and magnetic ordering temperature.