Study On Influence Of Rare Earth Element Oxide On Dielectric Properties Of Barium Strontium Titanium Oxide (BSTO) Ceramics

Barium strontium titanate ceramic-based samples were prepared with different raw materials, different BaTiO3/SrTiO3 ratio, different kinds and amount of rare earth oxides. Temperature and frequency dependence of dielectric constant were measured; microstructure of the samples were analyzed through X-ray diffraction patterns of the samples; morphology of the samples were observed; and tunability of part of the samples were obtained, on base of which phenomenological coefficient was calculated.Doping of rare earth oxides could improve temperature stability and dielectric constant at very high frequency of the samples, which is also beneficial for forming of other components. Different kinds of rare earth oxide took different effects in dielectric properties of BSTO ceramic at 1MHz, samples doped with heavy rare earth oxide possessed lower dielectric constant than that of light ones, while better temperature stability. Different effects also took on in the samples of different BaTiO3/Sr TiO3 ratio, when ratio of BaTiO3/SrTiO3 equal to 0.6/0.4, dielectric constant of doped samples were higher than the undoped one, while the opposite situation occurred to the samples when ratio of BaTiO3/SrTiO3 equal to 0.7/0.3.It could be certain that ion polarization took major role in the samples under high frequency, while relaxation polarization of spatial electrons under low range.X-ray diffraction patterns of the sample proved that ions of rare earth element took places of Ba2+ or Sr2+ of pervoskite structure of Ba1-xSrxTiO3.Influences on tunability of the samples were discussed. It was found that the raw materials, grain size and Curie temperature of sintered samples were the important ones. Phenomenological coefficient represented degree of order of the samples, the higher the Phenomenological coefficient, the higher the degree of order...