STRUCTURE, MICROSTRUCTURE AND MAGNETIC PROPERTIES STUDY OF CERAMIC COMPOSITE (La0.67Ca0.33MnO3)1-x/(Nano-sizedα-Fe2O3)x

Abstract

The structural, microstructure and magnetic properties of polycrystalline (La_0.67Ca_0.33MnO₃)1-x/(α-Fe₂O₃)x composites where x = 0%, 5%, 10%, 15%, 20% were investigated. Polycrystalline La_0.67Ca_0.33MnO₃ (LCMO) was synthesized via solid state reaction at high sintering temperature while for nano-sized Fe₂O₃ (20-50 nm) a commercial product was used. X-ray diffraction (XRD) patterns show that parent compound of La_0.67Ca_0.33MnO₃ is a single phase without any detectable impurity and give orthorhombic structure with space group Pbnm (62) while α-Fe₂O₃ is in cubic form with space group I a -3 (206). As Fe₂O₃ content x increases, the magnetization M values decrease as observed via Vibrating Sample Magnetometer (VSM) at room temperature. Higher magnetization is noticed inpure LCMO rather than in LCMO composites added with α-Fe₂O₃. However, Scanning Electron Microscopy (SEM) shows that nano-sized Fe₂O₃ mainly distributed at the grain boundary of La_0.67Ca_0.33MnO₃. The particle size of LCMO composites shows fluctuation; meanwhile particle size of α-Fe₂O₃ shows almost similar values except for sample with the addition of 15% of α-Fe₂O₃ where lowest particle size with higher coercivity and retentivity are observed. As compared to pure La_0.67Ca_0.33MnO₃, Fe₂O₃ doping level at the grain boundaries can be assumed to modify the magnetic properties of La_0.67Ca_0.33MnO₃.