Effect of vanadium doping on sintering and dielectric properties of strontium barium niobate ceramics

摘要

Strontium barium niobate, Sr_(0.5)Ba_(0.5)Nb_2O_6 (SBN50) ceramics doping up to 3 wt% V_2O_5 were fabricated by solid state reaction route, starting from raw materials (oxides and carbonates) of analytical grade. The phase composition, microstructure and dielectric properties were investigated by X-ray diffraction, scanning electric microscope and impedance analyzer. The results show that the addition of V_2O_5 improves sintering densification of SBN ceramic samples. The relative density of the samples firstly increases and then slightly decreases with increasing amounts of V_2O_5 and sintering temperature. With the help of the additive of 1 wt% V_2O_5, the relative density of the sample sintered at 1,280 ℃ for 3 h can reached 97.2%. Only single tetragonal tungsten bronze phase SBN exists in all the doped samples. With increase in V_2O_5 content, the dielectric constant of SBN ceramics at both room temperature and in the vicinity of the phase transition temperature increases significantly and the Curie temperatures (Tc) obviously shifts to low temperature as well as the dielectric loss remains below 0.06. The diffuseness in the phase transition is found to increase with increase in vanadium doping level. The addition of V_2O_5 results in an increased grain size associated with rod-like grain growth.