BaTiO3 powders were prepared by sol-gel method from different concentration of KOH aqueous solution and Ba/Ti molar ratio. Particle shape, size and crystal structure of prepared BaTiO3 powders were analyzed by SEM, XRD, and FT-IR. As the result of KOH concentration changing, spherical particles were obtained by condition more than 3 M and particle size decreased as concentration increasing. Different appearance showed between dried and sintered powders against changing of Ba/Ti molar ratio. In case of dried powders, the crystallinity decreased as molar ratio increasing. On the other hand, increased as molar ratio increasing in case of sintered powders.
Multilayer ceramic capacitor (MLCC) miniaturization has increased the demand for superfine powder due to its thin dielectric layer. Hydrothermally synthesized powder a pseudo-cubic phase resulting in poor dielectric properties due to size effect and hydroxyl ion inclusion in the lattice. We attempted a superfine (lower than 100 nm) highly tetragonal powder via a solvothermal method without precipitating agent. The lattice parameters and the relative amounts of tetragonal and cubic phases were determined using Rietveld refinement.
In this study, high purity fine powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of , the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives
The ferroelectric properties of barium titanate strongly depend on its microstructure, in particular, grain size and distribution. During sintering, usually exhibits abnormal grain growth, which deteriorates considerably the ferroelectric properties. A typical technique to suppress the abnormal grain growth is the addition of dopants. Dopant addition, however, affects the ferroelectric properties and thus limits the application of . Here, we report a simple but novel technique to prevent the abnormal grain growth of and to overcome the limitation of dopant use. The technique consists of stepwise sintering in a reducing atmosphere and in an oxidizing atmosphere. The materials prepared by the present technique exhibit uniform grain size and high dielectric properties. The technique should provide opportunities of having -based materials with superior ferroelectric properties.