Influence of Firing Temperatures on Crystal Structure and Microstructure of LiNbO3 Ceramics

Abstract

The effects of calcination temperature (500–800°C for 2 h) and sintering temperature (900–1025°C for 2 h) on the crystal structure and microstructure of perovskite lithium niobate (LN) ceramics were investigated. The LN ceramics were synthesized using the solid-state reaction method. The phase formation and microstructure of samples were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD results showed a single phase of LN powders which was successfully obtained using a calcination temperature of 600°C for 2 h with a heating/cooling rate of 5°C/min. With increased firing temperatures, the lattice parameter a of the calcined powders and sintered ceramics increased from 5.4912 to 5.4945 Å and 5.4952 to 5.5086 Å, respectively. The SEM result showed that the average particle size (0.31–0.39 μm) and the average grain size (0.63–2.81μm) increased with the increase of calcination and sintering temperatures, respectively. The maximum density and dielectric constant (4.46 g/cm3 and 754) were obtained from the sample sintered at 1000°C for 2 h.