Structure refinement, far infrared spectroscopy, and dielectric characterization of (1x)La(Mg1/2Ti1/2)O3xLa2/3TiO3 solid solutions

Abstract

Dielectric properties of (1−x)La(Mg½Ti½)O₃−xLa⅔TiO₃[(1−x)LMT-xLT] ceramics (0 ≤ x ≤ 0.52) have been studied at radio, microwave, and far infrared (FIR) frequency ranges. The crystal structure sequence in (1−x)LMT-xLT reported by different authors has been analyzed and revised. FIR spectroscopy was used to characterize the lattice contribution to the dielectric response at microwave frequencies. The complex dielectric function was evaluated from the reflectivity data and extrapolated down to a gigahertz range. Compositional variations of the fundamental microwave dielectric parameters estimated by different methods are compared and discussed. The dependence of the quality factor on the composition in LMT-LT is interpreted in terms of the reduction of spatial phonon correlations originated from the increasing amount of La vacancies. This approach could account for the compositional behavior of the dielectric loss commonly observed in a number of microwave mixed systems.