Magnetic properties of nano-clusters lanthanum chromite powders doped with samarium and strontium ions synthesized via a novel combustion method

A novel approach to synthesize a single-phase orthorhombic perovskite lanthanum chromite LaCrO3 clusters doped with Sm3+ and Sr2+ ions via gel combustion route was reported. The producing materials were synthesized using metal nitrates as oxidizers and triethanol amine (TEA), N-butyl amine (NBA) or ethylene diamine (EDA) as a fuel. The effect of the annealing temperature, type of organic fuel and the variation of the samarium and/or strontium substitution and its impact on crystal structure, crystallite size, microstructure and magnetic properties of the LaCrO3 powders formed was systematically studied. The results revealed that a well crystalline single phase of pure LaCrO3 can be achieved at annealing temperature from 800 to 1000 degrees C for 2 h. Moreover, each organic carrier materials exhibited a different degree of effectiveness in the synthesis of the mixed oxide powders. The crystal structure was influenced by doped Sm3+ and/or Sr2+ ions. The crystallite size of the produced powders was increased with the increase the annealing temperature, increasing the Sm3+ ion and the decrease of Sr2+ ion substitution. The microstructures of the produced powders were found to be nanoclusters octahedra-like shaped. The saturation magnetization of the LaCrO3 powders increased continuously with an increase in the Sm3+ ion concentration and it decreased with an increase in the Sr2+ ion up to 0.3 at annealing temperature of 1000 degrees C for 2 h. The maximum saturation magnetization (0.279 emu/g) was achieved at the Sm3+ ion molar ratio 0.3 and annealing temperature 1000 degrees C. Moreover, wide coercivities can be obtained at different synthesis conditions (49.25 to 522 Oe). (C) 2010 Elsevier Ltd. All rights reserved.