Raman spectra and dielectric properties of the nanocrystalline Li0.43Nb0.57O3+δ

The Li0.43Nb0.57O3+δ material was synthesized by a combustion method and sintered at various temperatures. The crystal structure, surface morphology, and dielectric properties of the as-prepared lithium niobate bulks were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectrum and an LCR meter. After sintering at 1100 °C, the structure of the Li0.43Nb0.57O3+δ was similar to the single crystal of lithium niobate. The thermal vibration of the elements caused the bond length of the Nb3O framework and angle bending of the O3Nb3O increase, and the structure was restored by the formation of square crystals in the quasi-melting Li0.43Nb0.57O3+δ matrix. The dielectric constant increased with the increasing sintering temperature before 1000 °C, and then fell due the formation of a split seam. The reduction in defects forming from the Li-site vacancies lowered the dissipation factor at higher sintering temperatures.