Structure-property relations in xBaTiO3-(1-x)La(Mg1/2Ti1/2)O3 solid solutions

The microwave dielectric properties and microstructures of compounds in the solid solution series xBaTiO3-(1-x)La(Mg1/2-Ti1/2)O3 (BTLMT) have been investigated. The structural phase transitions that occur as a function of x have been studied and are related to changes in the dielectric properties. For compounds where x ≤ 0.1, X-ray diffraction (XRD) showed evidence of 1:1 ordering between Mg and Ti cations. For x ≤ 0.3, XRD and electron diffraction revealed that compounds were tilted in both antiphase and in-phase. However, for 0.3 < x < 0.7, only antiphase tilting was present. The temperature coefficient of resonant frequency (τf) vs the relative permittivity (εr) was linear until x = 0.5 at which point in the solid solution the transition to a nontilted structure resulted in nonlinear behavior. τf values close to zero (-2 ppm/°C) were achieved at x = 0.5 (εr ∼ 60), which had a quality factor (Q·fo) of 9600 GHz.