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Small amounts of codoping La and Ga on the A and B sites of BaTiO3, respectively, resulting in a solid solution of the type Ba(sub{1-3x})La(sub 2x)Ga(sub 4x)Ti(sub {1-3x})Al(sub 4x)O(sub 3) are investigated. The resulting compounds exhibit a remarkable decrease in Curie temperature as well as a significant enhancement in the dielectric constant.

Small amounts of La and Al doping on the A and B site of BaTiO3, respectively, resulting in a solid state solution of the type Ba(sub{1-3x})La(sub 2x)Ti(sub{1-3x})Al(sub 4x)O(sub 3) are investigated. The Pechini process prepares the compositions.

Abstract: The effect of dielectric constant of the PbTiO3 dispersoid on the conductivity of Na2SO4 has been probed. At the Curie temperature, 490 °C, PbTiO3 undergoes ferroelectric to paraelectric phase transition followed by a sharp change in the dielectric constant. The Na2SO4–PbTiO3 composites have been prepared at two different temperatures, namely 600 and 900 °C. Compositions containing 5, 10, 20, 30, 40, 50 m% PbTiO3 have been investigated using Impedance Spectroscopy, Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and Rietveld analysis. The series of compositions prepared at 900 °C exhibit a maxima in the conductivity for 20 m% PbTiO3. The composites prepared at 600 °C exhibit a peak in the conductivity at 20 m% PbTiO3 in addition to the percolation threshold at 40 m% PbTiO3. The enhancement in the conductivity by a factor of 40 at 300 °C has been observed for the system prepared at 600 °C while an enhancement in the conductivity by a factor of 8 at 300 °C has been observed for the system prepared at 900 °C. Further, the transition temperature of Na2SO4 remains unaltered for both series. A slight nonlinearity has been observed in the vicinity of the transition temperature of the dispersoid. [Copyright &y& Elsevier]

Abstract: In this work, Y2O3 was evaluated as a gate insulator for thin film transistors fabricated using an amorphous InGaZnO4 (a-IGZO) active layer. The properties of Y2O3 were examined as a function of various processing parameters including plasma power, chamber gas conditions, and working pressure. The leakage current density for the Y2O3 film prepared under the optimum conditions was observed to be ~3.5×10−9 A/cm2 at an electric field of 1 MV/cm. The RMS roughness of the Y2O3 film was improved from 1.6 nm to 0.8 nm by employing an ALD (Atomic Layer Deposition) HfO2 underlayer. Using the optimized Y2O3 deposition conditions, thin film transistors (TFTs) were fabricated on a glass substrate. The important TFT device parameters of the on/off current ratio, sub-threshold swing, threshold voltage, and electric field mobility were measured to be 7.0×107, 0.18 V/dec, 1.1 V, and 3.3 cm2/Vs, respectively. The stacked insulator consisting of Y2O3/HfO2 was highly effective in enhancing the device properties. [Copyright &y& Elsevier]