Preparation And Characterizations Of BaCeO3Nanopowders

BaCeO3is a very important ceramic material with wide application prospects as the catalysts for water splitting and exhaust gas purification, as proton conductor, so it has become an important member of the perovskite type oxides. In order to obtain excellent performances and good microstructure, BaCeO3powders are acquired to have the characteristics of fine particle size, narrow particle size distribution and good dispersion. So it is of great signification to study the preparation process of BaCeO3nanopowders. Single phase BaCeO3nanopowders with cubic structure were prepared by Pechini method and modified sol-gel method; the effects of the concentration of total metal nitrates, water-bath temperature on the quality of sol and gel formed were discussed; the phase transformation of the precursors during the calcinations was investigated by means of TG-DTA and XRD; the influences of reaction conditions on particle size and agglomeration degree of BaCeO3nanopowders were studied by SEM analysis.It is found that single phase BaCeO3nanopowders with cubic structure were prepared by Pechini method, using citric acid as a chelating agent. The results show the concentration of total metal nitrates and water-bath temperature could greatly influence on the formation of colloid, and the optimized concentration of total metal nitrates and water-bath temperature are0.05mol/L and70℃. The calcinations temperature, molar ratio of citric acid to metal nitrates and molar ratio of ethylene glycol to citric acid having great influence on the single phase formation was found through XRD analysis, the optimized calcinations temperature, molar ratio of citric acid to metal nitrates and molar ratio of ethylene glycol to citric acid are900℃,5:1and2:1respectively. SEM results show that the sample gained is most made up of plate shape aggregates composed of small particles, and made up of well dispersed and much smaller particles (about50nm) but only a few.Single phase BaCeO3nanopowders with cubic structure were synthetized by modified sol-gel method, using citric acid and EDTA as chelating agents. The results show that the gel obtained is transparent and homogenous, when the water-bath temperature is70℃and concentration of metal nitrates is0.005mol/L. The calcinations temperature and time having great influence on the single phase formation was fount through XRD analysis, the optimized calcinations temperature and time are900℃,4h respectively. SEM results show that the molar ratio of EDTA to citric acid, pH value, concentration of NH4NO3have certain influence on particle size and agglomeration degree. On the optimized reaction conditions (the molar ratio of EDTA to citric acid, pH value and concentration of NH4NO3are1:1,8-9, and0.02mol/L respectively), the sample was made up of much smaller (about100nm) and well dispersed particles.