IMF2017

Ba{[Ga_x,Ta_x]Ti_(1-2x)}O₃ with x equal to 0, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.075 and 0.1 have been prepared by conventional solid-state reaction and sintered to > 95% density. Structural and dielectric characterization has been performed to investigate the effect of dipole-like concentration on the properties. Dielectrically, the Ba{[Ga_x,Ta_x]Ti_(1-2x)}O₃ phase transition evolves from a classic ferroelectric to a diffuse phase transition (DPTs) as x increases. The Ba{[Ga_0.01,Ta_0.01 ]Ti_0.98 }O₃ possesses diffuseness parameter comparable to Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT), yet it lacks the frequency and temperature dependence of T_m. For a given DC bias, Ba{[Ga_x,Ta_x]Ti_(1-2x)}O₃ possesses capacitance tunability exceeding that of PMN-PT. In comparison to BaTiO₃, Ba{[Ga_x,Ta_x]Ti_(1-2x)}O₃ possesses enhanced electrical resistivity and greater time constant at and above room temperature. The diffuseness of ε_r is found to increase linearly with the dipole concentration. In-situ XRD, including Rietveld refinement, has been performed to determine the lattice parameter, coefficient of thermal expansion and phase transition temperature of each composition within the temperature range [RT, 1000 ^°C]. The unusual properties of Ba{[Ga_x,Ta_x]Ti_(1-2x)}O₃ will be discussed in context with available models describing donor and acceptor dopants spatially separated in the parent matrix that inter-relate lattice parameter, Curie temperature, and other properties.