Development and characterization of spark plasma sintered bismuth ferrite (BiFeO3) multiferroic ceramics

Abstract

BiFeO3 (BFO) Ferrite ceramics were synthesized by an improved solid-state technique in conjunction with high-energy ball milling. Calcination was carried out at 800°C for 2 hours at a heating rate 5 °C/min and cooling rate was same as heating rate. High density BiFeO3 ceramics were further sintered using by Spark Plasma Sintering (SPS) at different temperatures. Comparatively minimal amount of secondary phases was achieved than conventional sintering because of the higher heating rate with less holding time. They were contrived by different characterization techniques such as X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDS), Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Ferromagnetic, Ferroelectric and Piezoelectric Measurements, Raman Spectroscopy, Fourier-Transform Infrared Spectroscopy (FTIR) as well as shaped up Linear Optical Properties. The sintering conditions were optimized in order to attain high density, minimal amount of secondary phases and improved magnetic, piezoelectric and optical properties. The optimal structure and properties were achieved after Spark Plasma Sintering at 750°C for 5 minutes, under uniaxial pressure of 50 MPa. It was found that with decreasing grain size there occurs an enhancement in magnetization. This enriched magnetization is attributed to the improved grain boundaries. BFO-750 showed copious % transmittance about 27 with a long-range wavenumber. Piezoelectric measurements using a quasi-static method based on the Berlincourt method confirmed that conspicuous d33 coefficient measured maximum 7.2 ± 0.5 pCN-1 without poling. Ferroelectric hysteresis loop measurement revealed that the samples have good ferroelectricity except BFO-800 and BFO-825 samples. Raman spectroscopy confirmed that there were maximum 13 modes formed in BFO-750. SPS + high density ball milling was supposed to be responsible for the outstanding obtained properties.

Keywords: Multiferroic, Perovskite, SPS, BFO, Piezoelectric, Optical properties.