Synthesis of Al-substituted BiFeO3 powders and investigation of their properties

Abstract

Multiferroics with chemical formula BiAlxFe1-xO3 (x=0, 0.1, 0.2 and 0.3) and substituted by Al are synthesized using sol-gel auto-combustion method. These materials are sintered at temperature 500oC for 5 hours. In the ongoing study, the effects of Al substitution on the structure and different physical parameters of above described multiferroics have been discussed. The crystal structure of BiFeO3 was investigated by X-ray diffraction (XRD). After that, various characterization techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping images, Fourier transform infrared spectroscopy (FTIR), and vibration sample magnetometery (VSM) were used to investigate the synthesized samples. The rhombohedral single phase structure is confirmed by XRD analysis. The grain size is calculated by SEM results. EDX analysis was performed for the identification of the elements present in the specimens. The elemental mapping images investigate the distribution of the elements in the sample. FTIR spectrum of the sample shows the absorption peak of the Al doped sample. The VSM results of Al-doped BFO were performed at room temperature. It is well known that BiFeO3 crystals with size greater than 60 nm show anti-ferromagnetic behavior which is evident in the present study. The increase in Al doping results an increase in coercivity as both grain size and coercivity are inversely related with each other. This is because of the replacement of Fe3+ by Al3+ ions which weakens the sub-lattice interactions. It has been observed earlier that BiFeO3 materials with such parameters are favorable for ferroelectric random access memories (FeRAM), where data can be written electrically and read magnetically.