Study On Piezoelectric Catalytic Activity Of Niobate Lead-free Piezoelectric Ceramics

Piezoelectric ceramics are a kind of multifunctional materials.The unique piezoelectric effect of piezoelectric ceramics makes piezoelectric ceramics have significant advantages in piezoelectric catalysis.Potassium sodium niobate(KxNa1-xNbO3,KNN)based ceramics have become one of the preferred piezoelectric materials because of their high piezoelectric constant.In this paper,niobate ceramic powders with different morphologies were prepared by hydrothermal method and molten salt method,and the samples were annealed in atmosphere.The effects of morphology,defects and reaction conditions on piezoelectric catalytic activity were studied.The main research contents of this paper are as following:(1)The cubic NaNbO3(NN)powders were prepared at different temperatures and time.The particle size decreased with the increase of reaction temperature and increased with the increase of reaction time.The NN ceramic powder with smaller particles shows better piezoelectric catalytic activity than the ceramic powder with larger particles.The ceramic powder was annealed in N2 atmosphere,which significantly improved the piezoelectric catalytic activity of NN ceramic powder.The sample annealed at 180℃ for 12 h showed the best piezoelectric catalytic activity,and the degradation efficiency constant reached K=131.7×10-3 min-1.The leading role of hydroxyl in the catalytic process was determined by free radical trapping experiments.(2)The rod-like K2Nb8O21 precursor was prepared by solid-state reaction method,and the rod-like KNN ceramic powder was prepared by molten salt method.The effect of reactant ratio on the composition of the product and the piezoelectric catalytic activity of KNN ceramic powder were studied.The sample showed the best piezoelectric catalytic activity when the K/Na in the product was close to 1.The ceramic powders were annealed in different atmospheres to form the piezoelectric catalytic activity.The sample with Na2CO3:K2CO3=53:47 showed the best piezoelectric catalytic activity,and the degradation efficiency constant K=162.6 × 10-3 min-1.