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 °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 °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 °C. Moreover, wide coercivities can be obtained at different synthesis conditions (49.25 to 522  Oe).

Nanocrystalline Sm3+ and Sr2+ doped LaCrO3 powders have been synthesized through a novel gel combustion synthesis using triethanol amine (TEA). The saturation magnetization of the LaCrO3 increased with an increase Sm3+ ion and it decreased with an increase in the Sr3+ ion to 0.3 at temperature 1000 °C for 2 h due to the formation of a monodispersed uniform octahedral structure as shown in the Fig.Figure optionsDownload as PowerPoint slideResearch highlights▶ Single-phase orthorhombic lanthanum chromite LaCrO3 nanoclusters have been successfully synthesized through a novel gel combustion synthesis using triethanol amine (TEA). ▶ Sr2+ ions doped LaCrO3 increased the unit cell volume and the crystallite size whereas Sm3+ ions doped LaCrO3 decreased the unit cell volume and the crystallite size. ▶ The saturation magnetization of the LaCrO3 powders increased continuously with an increase in the Sm concentration and it decreased with an increase in the Sr ion up to 0.3 at annealing temperature of 1000 °C for 2 h.