Phase transition and dielectric properties of BaTiO3 ceramics containing 10 mol% BaGeO3

Dielectric properties and the cubic ? tetragonal phase transition temperature ofdense BaTiO3 ceramics containing 10 mol% BaGeO3, sintered between 840 and 1350 °C,have been investigated. The ceramic bodies were prepared from a nano-sized BaTi0.9/Ge0.1O3powder consisting of both BaTiO3 and BaGeO3 phases. The addition of BaGeO3 leads to areduction and broadening of the permittivity maximum, and to a small downshift of theparaelectric ? ferroelectric phase transition temperature, compared to a pure BaTiO3 ceramic.Lower sintering temperatures and thus small grain sizes of the ceramics cause an additionalreduction of the maximum permittivity down to 2800. Both DTA and dilatometricmeasurements reveal also a downshifting of the phase transition temperature, as well as adecrease of the latent heat.