Structural, magnetic and catalytic properties of La2-xBaxCuO4 (0 <= x <= 0.5) perovskite nanoparticles

Barium doped La2CuO4 perovskite nanoparticles were synthesized via microwave assisted combustion method. The effects of Ba2+ doping on structural, optical, magnetic and catalytic activity of La2CuO4 have been studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) and vibrating sample magnetometer (VSM) techniques. The XRD patterns of pure La2CuO4 and La1.9Ba0.1CuO4 confirmed the formation of perovskite structure without impurities. However, with increasing Ba2+ content in the range 0.2-0.5, phase transformation from orthorhombic to tetragonal structure, occurred. The average crystallite size of orthorhombic and tetragonal phases were in the range 45.2-52.2 nm and 0.5-41 nm, respectively. The appearance of FT-IR bands at around 685 and 517 cm(-1) were correlated to the La-O and Cu-O stretching modes of orthorhombic La2CuO4 phase. The direct band gap estimated using Kubelka-Munk (K-M) method decreased with the increase in Ba2+ content (1.88-1.64 eV), due to the formation of sub-bands in the energy band gap. Magnetic measurements of doped La2CuO4 samples showed either para- or ferro-/para- magnetic behaviour at room temperature. The catalytic activity (oxidation) tests carried out in a batch reactor operating under atmospheric conditions indicated that the prepared catalysts, in particular (La1.7Ba0.3CuO4), showed excellent catalytic activity.