Study On The Synthesis Of Barium Titanate Nanopowder For Ceramic Capacitor Medium

Multilayer Ceramic Capacitor(MLCC)is one of the most widely used component in modem electronics.Barium titanate(BaTiO3)nano-powder is the key raw material for the development and production of high performance MLCC.A large number of studies have been taken to demonstrate that the comprehensive performance of MLCC,especially dielectric constant and breakdown performance,depend mostly on the synthesis method of BaTiO3 nano-powders.For this reason,BaTiO3 nano-powders were synthesized by four different synthetic methods:PECHINI,electrochemical method,hydrothermal method and microwave-assisted hydrothermal method.Also and their phase composition,grain size,morphology and distribution range were characterized.The results of X-ray diffraction and Raman spectroscopy analysis show that the main crystalline phase of BaTiO3 nano-powders synthesized by the above four methods is cubic phase,but contains a very small amount of tetragonal phase.BET measurements show that the specific surface area of BaTiO3 nano-powders obtained by the above-mentioned methods varies in the range of 10-10 m2 g-1.Among these methods,Pechini method can obtain smallest grain size,about 44 nanometers.Through electrochemical synthesis,the average diameter of the grain is 67±20 nm,but the distribution range of the grain diameter is larger.At the same time,the study also shows that through hydrothermal method,the grain size of BaTiO3 nano-powders is 180±60 nm,while when synthesized by microwave-assisted hydrothermal method,smaller BaTiO3 nano-crystals(66±16 nm)can be obtained in a shorter reaction time.BaTiO3 nano-powders with different grain size and distribution characteristics can be synthesized effectively by these four methods.In order to compare the effect of powder synthesized on MLCC performance,50 nm(microwave hydrothermal process)and 200 nm(hydrothermal synthesis process),were used as raw materials for the preparation MLCC layers(2.6-2.8 ?m),which were prepared according to the existing process flow.The final performance analysis shows that the MLCC prepared with 50 nm BaTiO3 nano-powder has larger capacitance(larger dielectric constant)and higher breakdown voltage,compared with MLCC prepared with 200 nm BaTiO3 nano-powder.The results show that the synthesis of BaTiO3 nano-powder by microwave hydrothermal process not only has smaller grain size and narrower particle size distribution,but also is easier to densify during final sintering.Therefore,the comprehensive performance of MLCC can be further improved.