Effect of Sintering Temperature on Nanostructured Multiferroic BiFeO₃ Ceramics

Abstract

Nanostructured multiferroic BiFeO3(BFO) powders were synthesized by using the co-precipitation method. Calcination of acquired powder was carried out at 400°C for 3h. Uniaxially pressed pellets were sintered at 500°C, 600°C, 700°C and 800°C for 2 hours in air. These samples were characterized for structural, thermal, electrical and magnetic properties. X-ray diffraction (XRD) confirmed the amorphous nature of the as driven powder and phase purity of the calcined BFO sample. The crystallite size varied with the sintering temperature from 52 to 70 nm. Sintering above 500°C induced impure phases due to oxygen vacancies and volumetric strain in crystal structure. Ferroelectric to paraelectric transition temperature TC~815°C was verified by the differential scanning calorimetry (DSC). Surface morphology and grain growth was observed using scanning electron microscopy (SEM). Electrical ac measurements were performed in the frequency range from 20 Hz to 3 MHz at room temperature. For a particular sample, capacitance decreased and susceptance increased with the increase of applied frequency signal. These parameters were increased with the increase of sintering temperature. Vibrating sample magnetometer (VSM) revealed the diverse weak ferromagnetic behavior for the samples sintered at different temperatures. Maximum coercivity (Hc~119.2 Oe) and maximum remnant magnetization (MR~2.1x10-3emu/g) were obtained for the sample sintered at 700°C for 2hr.

Structural, Dielectric, and Magnetic Properties of Ba-Doped Multiferroic Bismuth Ferrite

“…and Fe 3? ) cause a high leakage current in the material that degrades its ferroelectric properties [10][11][12]. On the other hand, the localized ferromagnetism produced by the canting of spins in BiFeO 3 vanishes at macroscopic level due to the spiral spin structure [8][9][10][11][12][13].…”

Impedance and Modulus Spectroscopy Characterization of Tb modified Bi0.8A0.1Pb0.1Fe0.9Ti0.1O3 Ceramics

“…The disadvantages of these materials are that they possess weak ferroelectric (polarization) and ferromagnetic order parameters. Large number of oxygen vacancies produced due to highly volatile nature of Bi and the multiple oxidation states of Fe (Fe 2+ and Fe 3+ ) cause a high leakage current in the material that degrades its ferroelectric properties [9][10][11] . In order to (i) enhance ferroelectric (polarization) and ferromagnetic order parameters and (ii) reduce leakage current several attempts have been made to replace A and B site of pure BiFeO 3 3 powders were found that bulk densities increased up to 93% of theoretical density and dielectric properties also improved by the Pb-doping as compare to pure BiFeO 3 19 .…”

Effect of sintering temperature on magnetoelectric properties of PbTiO3/NiFe2O4 composite ceramics

“…The dielectric loss is the largest when the sintering temperature is 950 °C. On the one hand, grain boundary, the defect will cause the change of dielectric loss value [29]. On the other hand, the irregular grain size will lead to the abnormal interaction between grains and grain boundaries, which will lead to the increase of friction caused by the domain wall motion and thus, leading to the increase of dielectric loss.…”