Investigation of Aluminium and Manganese doped BiFeO3 Multiferroic

Abstract

ABSTRACT newline newline Among all the multiferroics BiFeO3 (BFO) is considered one of the prime candidates that exhibit strong coupling between ferroelectric and ferromagnetic behavior at room temperature which further leads to room temperature device applications. BiFeO3 possesses high Curie temperature (TC~830°C) and antiferromagnetic Neel temperature (TN ~370°C). So, in the present investigation pure BFO, iron excess and deficient samples were synthesized via citrate precursor method sintered at 600°C for two hours. The samples were characterized using different techniques such as X-ray diffraction, Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, Raman, Vibrating sample magnetometer, Polarization-Electric field loop Tracer and Keithey to study the various structural, morphological, optical, electrical and magnetic properties. The values of retentivity, coercivity and saturation magnetization in iron excess BFO sample was found to be 0.047 emu/g, 102 Oe and 0.567 emu/g respectively which is almost double the value of pure BFO. Among the three samples, BiFe1.2O3 is found to have good electrical, dielectric and magnetic properties. newline newlineA series of Manganese doped BFO with composition BiMnxFe1-xO3 (x = 0.0, 0.025, 0.05, 0.075 and 0.1) has been prepared via citrate precursor method sintered at 600°C. Structural, morphological, optical, electrical and magnetic properties were investigated by XRD, FESEM, TEM, FTIR, RAMAN, VSM, P-E loop Tracer and Keithley. All the samples exhibit improved magnetic, dielectric and electrical properties. M-H loop illustrated that by introducing Mn at B-site, the retentivity of the samples increases from 0.0514 emu/g of BFO to 0.0931 emu/gm of 10% of Mn doping. Saturation magnetization was observed to be increase from 0.671 emu/g for BFO to 0.8025 emu/g for 7.5% Mn doping and then decrease to 0.6725% emu/g for 10% Mn doping BFO. At x= 0.1, dielectric constant was observed to be 142 measured at 1 kHz. The increased magnetization, high dielectric constant and good electrical properties of Mn doped BFO provides new impulse in the development of new devices such as magnetic random access memories, spintronics and data storage devices. newline newlineAnother series of Al doped BFO with composition BiAlxFe1-xO3 (x = 0.0, 0.025, 0.05, 0.075 and 0.1) was prepared via citrate precursor method sintered at 500°C. School of Physics and Materials Science newlineNo structural change was observed with the introduction of Al at B-site. It was found that substituting Al at octahedral site greatly reduced the leakage current density and hence enhances the ferroelectric properties. Dielectric properties increased with the Al doping content and found to be maximum for x= 0.1. In addition to this, low dielectric loss tangent was observed in the samples. However, magnetization decreases with the incorporation of a non-magnetic Al3+ ion at B-site. Substitution of Al in pure BFO leads to improved dielectric and electrical properties in the samples and hence makes this material useful in various multifunctional device applications. newline newline newline