The phase transformations from amorphous to pyrochlore to perovskite in lead scandium tantalate (PST) thin films during a rapid thermal annealing (RTA) process have been studied. Volume fractions for pyrochlore and perovskite were obtained from their respective x-ray diffraction intensities. Two models assuming the starting phase being either pure amorphous or pyrochlore were analysed in detail. Equations have been derived and numerical calculations have been used to simulate the volume fractions for each phase as functions of annealing time. Transformation parameters k and n were obtained by comparing the simulated to the experimental volume fractions using a least-squares curve fitting technique. Transmission electron microscopy, SEM and energy dispersive x-ray spectroscopy were employed to study the lead loss and other factors affecting phase transformations. It is concluded that the starting materials in the PST films deposited at 300˚C were mixture of amorphous and pyrochlore and the phase transformations upon RTA are diffusion limited.

The frequency‐dependent microwave complex permittivity of composites based on an Al2O3–CuO system is investigated at room temperature. The composites are formed by solution infusion of copper precursors into a porous Al2O3 matrix, followed by thermal decomposition to copper oxides and localized formation of copper aluminate compounds, and finally, H2 firing. The material exhibits a strong amplitude, with relatively narrowband dielectric resonance in the microwave frequency regime at intermediate levels of mass gain, which is reminiscent of a plasmon resonance. Large mass gains cause negative permittivity behavior below 6 GHz, consistent with a collisional Drude model of a semiconducting oxide phase.

The complex dielectric permittivity of electrically lossy, porous Al2O3–SiC composites was measured as a function of frequency over the range of 0.001 to 18 GHz. These composites were fabricated by an infusion method of incorporating SiC polymer precursor into porous alumina disks. Repeat polymer infusions and pyrolysis steps to 1000 °C were carried out, with some samples undergoing an additional air fire prior to each subsequent step. Generally, it was found that for non-air-fired samples, moderate, controllable losses were attainable over a broad frequency range. By contrast, the dielectric loss attainable for air-fired samples was generally very low. For all samples, various aspects of the variation of permittivity components ϵ′ and ϵ″ with frequency were analyzed, with a view to determine the various factors contributing to dielectric response. Microstructure analysis using scanning electron microscopy was also performed.

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The phase transformations from amorphous to pyrochlore to perovskite in lead scandium tantalate (PST) thin films during rapid thermal annealing process (RTA) have been studied. Volume fractions for pyrochlore and perovskite were obtained from their respective X-ray diffraction intensities. Two models assuming the starting phase being pure amorphous or pyrochlore were analysed in detail. Equations have been derived and numerical calculation used to simulate the volume fractions for each phase as functions of annealing time. Transformation parameters k and n were obtained by comparing experiment with simulation using a least-squares curve fitting technique.