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Heteroepitaxial growth of BaSnO3 and Ba1-xLaxSnO3 (x = 7%) lanthanum doped barium stannate thin films on different perovskite single crystal (SrTiO3 (001) and SmScO3 (110)) substrates has been achieved by pulsed laser deposition under optimized deposition conditions. X-ray diffraction measurements indicate that the films on either of these substrates are relaxed due to the large mismatch and present a high degree of crystallinity with narrow rocking curves and smooth surface morphology while analytical quantification by proton induced X-ray emission confirms the stoichiometric La transfer from a polyphasic target, producing films with measured La contents above the bulk solubility limit. The films show degenerate semiconducting behavior on both substrates, with the observed room temperature resistivities, Hall mobilities, and carrier concentrations of 4.4 mΩ cm, 10.11 cm² V-1 s-1, and 1.38 × 1020 cm-3 on SmScO3 and 7.8 mΩ cm, 5.8 cm² V-1 s-1, and 1.36 × 1020 cm-3 on SrTiO3 ruling out any extrinsic contribution from the substrate. The superior electrical properties observed on the SmScO3 substrate are attributed to reduction in dislocation density from the lower lattice mismatch. [ABSTRACT FROM AUTHOR]

In situ synchrotron x-ray powder diffraction has been used to study the kinetics of cation ordering and disordering in the microwave dielectric electroceramic Ba3CoNb2O9 with a time resolution of 15 s. The method enables the order/disorder temperature (To/d) in this material of 1430 °C to be directly observed. The changes in the rate and degree of cation ordering and in the growth of ordered domains between samples ordered from standard precursor material and then subsequently reordered following an annealing period above To/d show that small changes in precursor order state and phase assemblage strongly influence the final domain size. [ABSTRACT FROM AUTHOR]

The ceramic Ba[SUB8]ZnTa[SUB6]O[SUB24] has been synthesized in isolation and its dielectric and crystallographic properties characterized. The material affords excellent dielectric properties, with a high unloaded quality factor Q[SUBu] = 20 800 at 3.28 GHz, high relative permittivity &epsis;[SUBr] = 29 and a temperature coefficient of resonant frequency τ[SUBf] = 29.4 ppm/°C. The crystal structure adopted is complex, comprising mixed cubic and hexagonal perovskite subunits, and contains cation vacancies on the octahedral sites. A second phase with a closely related structure is identified, demonstrating the existence of a family of materials. This structural complexity offers diverse opportunities for substitutions calculated to enhance the figures of merit reported. [ABSTRACT FROM AUTHOR]