Abstract
SrTiO3 solid solutions containing Sr0.5NbO3 were studied by X-ray diffraction and dielectric measurements. Single-phase perovskite solid solutions were formed up to the composition containing 30 mole % Sr0.5 NbO3. The addition of niobium resulted in a symmetry change from cubic (SrTiO3) to tetragonal (solid solution) and the c/a ratio increased with increasing niobium content. The dielectric constant for the solid solutions was lower than that for SrTiO3. Pronounced dielectric relaxation peaks and dispersion in permittivity were observed for the composition 7SrTiO3:3Sr0.5NbO3. The activation energy for the relaxation process is about 0.42 ev. It is suggested that the existence of the A-site vacancy in the perovskite ABO3 lattice introduced by the niobium substitution distorts the oxygen octahedra, producing more than one possible “noncentral” site for the Ti4+ ion. The relaxation arises from the thermal motion over potential barriers separating these alternative sites.
Published Version
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