Dependence on sintering temperature of structure, optical and magnetic properties of La0.625Ca0.315Sr0.06MnO3 perovskite nanoparticles

Abstract

Abstract In this study, La0.625Ca0.315Sr0.06MnO3 (LCSMO) nanoparticles were prepared by facile sol-gel method at low crystallization temperatures. Various test methods were used to characterize structure, optical and magnetic properties of LCSMO nanoparticles. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) suggested complete crystallization of LCSMO nanoparticles sintered at 700 °C. In addition, unit cell volume and grain size increased with sintering temperature. Besides, X-ray photoemission spectroscopy (XPS) fitting results of Mn2p core level peaks confirmed the increase in Mn3+ ion concentration with sintering temperature, mainly attributed to formation of more oxygen vacancies. Raman microscopy and Fourier transform infrared spectrometry (FTIR) jointly depicted the existence of Mn–O bond, indicating that sintering temperature definitely impacted vibration mode of Mn–O and affected both crystal structure and performance. UV–vis optical band gap width of LCSMO nanoparticles sintered at 700 °C, 1000 °C, and 1500 °C decreased from 1.2 to 0.75 eV as sintering temperature increased, suggesting the semiconducting properties of nanoscale LCSMO particles. Magnetization dependent temperature (M-T) and magnetic field (M-H) measurements revealed degradation in magnetic properties of the specimens with temperature. Overall, LCSMO nanoparticles sintered at different sintering temperatures provided novel insights into properties of rare earth doped perovskite manganites.