Preparation And Properties Research Of BST Ceramic Doped By Glass Additives

Barium strontium titanate was an important non-linear dielectric electroceramic materialwith perovskite-type structure. BST was complete solid solutions formed by BaTiO₃andSrTiO₃, and it had the characteristics of high dielectical property of BaTiO₃and low dielectricloss and structural stability of SrTiO₃. The dielectric constant and Curie temperature could beadjusted within a relatively wide range by changing the Ba/Sr ratio and the material dielectricconstant-temperature stability could be ensured. BST material was used widely in the fields ofmicrowave transmission, signal processing and information storage.Pure Ba_0.6Sr_0.4TiO₃and Ba_0.6Sr_0.4TiO₃doped Dy-B-Si-O glass additive were prepared bysol-gel method with barium acetate, strontium acetate, titanium tetrabutoxide as raw materialsand dysprosium acetate, tributyl borate, silicic acid tetracthyl ester as dopants. Pure BSTceramics and BST ceramics doped Dy-B-Si-O glass additive were obtain sintering at differenttemperature. Main phases structure, particle size, the chemical reaction and energy changes inthe calcination process of Ba_0.6Sr_0.4TiO₃powder and Ba_0.6Sr_0.4TiO₃powder doped Dy-B-Si-Oglass additive were analyzed by X-ray diffraction, laser particle size analyzer, differentialthermal analyzer. Microstructures and dielectric properties of BST ceramics and BSTceramics doped Dy-B-Si-O glass additive were analyzed by SEM and automatic componentanalyzer.The results showed that the main crystal phase of pure BST ceramics was a perovskite typestructure and the BST ceramics with appropriate B₂O₃-SiO₂in Dy-B-Si-O glass additive had aperovskite type structure. However, the secondary phase Ba₂TiSi₂O₈was detected whenB₂O₃-SiO₂in Dy-B-Si-O glass additive excess doped and increased with the increasing ofB₂O₃-SiO₂. The best calcination temperature and sintering temperature of BST dry gel withDy-B-Si-O glass additive was700℃and1100℃respectively. The temperature decreasedby about100℃and150℃compared with pure BST.The density of BST ceramics increasedand the grain size of BST powder decreased by doping Dy-B-Si-O glass. With the increasingof Dy2O₃content in Dy-B-Si-O glass additive, the dielectric constant increased and the dielectric loss increased firstly and then decreased. With the increasing of B₂O₃-SiO₂contentin Dy-B-Si-O glass additive, the dielectric constant increased firstly and then decreased, thedielectric loss decreased firstly and then increased, the Curie temperature moved toward tolower temperature firstly and then to higher temperature.