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Microstructure and dielectric properties of La 2 O 3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La 2 O 3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V A . The unit cell volume increased and then decreased slightly with the increasing La 2 O 3 content. Relatively high non-stoichiometric level and high La 2 O 3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant rRT , dielectric loss tanδ RT and the maximum relative dielectric constant rmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La 2 O 3 doping content, the relative dielectric constant rRT increased initially and then decreased. The maximum relative dielectric constant rmax can be increased by applying low doping content of La 2 O 3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

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