Hydrothermal synthesis and characterization of LiNbO3 crystal

Lithium niobate crystal was successfully synthesized via hydrothermal synthesis method using LiOH·H2O or LiNO3 and Nb2O5 as starting materials in water or ammonia solution. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectra and Scanning electron microscopy (SEM) were used to characterize the as-prepared samples. The synthesis conditions such as crystallization temperature and time as well as ammonia concentration (when using LiNO3 as Li source) were investigated. The results demonstrate that the crystallization and purity of the as-prepared samples were increased with the increase of time when temperature was at 260 °C. When using LiNO3 as Li source a basic solution was necessary to synthesize LiNbO3. In the present work ammonia solution was used instead of water to obtain alkalescence solvent. XRD results revealed that the as-prepared samples had a hexagonal structure. FT-IR results displayed that the LiNbO3 phase could be completely formed and no secondary phase was found under proper conditions. SEM picture showed that the morphology of the sample was more perfect and bigger with increasing reaction time.