Study On Preparation Of BaTiO₃ Adulteration Solid Solutions And Control Of Crystal Morphology

Nowadays, with development of electron industry, more highperformances of BaTiO₃ ceramic device are demanded, such as highprecision,high dependability,miniaturization,customization and so on.With improvement of microstructure and tissue through the adulteration andcontrol of crystal morphology routes, BaTiO₃ of different performance havebeen prepared, which could be applied in more fields. In this paper,spherical and fibrous/whiskery BaTiO₃ adulteration solid solutions havebeen synthesized respectively by the homogeneous precipitation method andthe hydrothermal-in-situ growth method.A series of Ba_1-xSr_xTiO₃ (BST) (0≤x≤1) and BaZr_xTi_1-xO₃ (BZT)(0≤x≤1) adulteration solid solutions have been synthesized through thehomogeneous precipitation route. Microcosmic Structure, composition andmorphology of those solid solutions were studied respectively by XRD,SEM and AFM. The results showed that their cell parameters were linearlyrelated with their composition, which accorded with Vegard's law and thatthe powders have mutual miscibility, spherical shape, uniform distributionand precision component. Study on the reaction condition showed that withthe increase of temperature, the crystallinity would be improved and grainsize would enlargen, that with the increase of reaction time, the crystallinitywould be improved and grain size would enlarge too a. firstly, the yield ofproduction would increase quickly, and after time, it would not almostchange. During the process of preparation, the pH value 3～4 should becontrolled strictly and TiCl₄ concentration of experiment should be 5% morethan that of theory. The compound mineralizing agent urged aggregationgrowth of the BST and BZT particles in solutions with dispersants viamaking the homogeneous reaction system and releasing hydroxyl.A series of Ba_1-xSr_xTiO₃ (BST) (0≤x≤1), BaZr_1-xTi_xO₃(BZT) (0.7≤x≤1) solid solutions whisker/fiber, which their cell parameters werelinearly related with their composition in accord with Vegard's law, weresynthesized through the hydrothermal-in-situ growth route. Study on thereaction condition show, that BST/BZT fiber should be synthesized through the hydrothermal-in-situ growth route at the temperature (160℃) above pH7, in the time (48 h). Through the high temperature 1200℃processingand recrystallization, BST,BZT fiber will change into whisker. At last, inthe paper, the growth-in-situ mechanism ofBST,BZT fiber was explained.