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In this study, we prepared a homogeneous fine powder of barium titanate (BaTiO3, BT) doped with different concentrations of strontium (x = 0, 0.05, 0.125, 0.15, 0.20, and 0.3) and having the composition Ba1-xSrxTiO3 (barium strontium titanate, BSrxT). XRD patterns and Rietveld refinement revealed the existence of a single tetragonal phase structure for BSrxT, x = 0–20%, and a single cubic structure for BSr30%T. The physical properties of the pure and doped mixtures were studied. The results showed that the addition of strontium to the physical properties of BaTiO3, including the apparent porosity, bulk density, linear shrinkage, and water absorption have been changed when increasing the Sr content. Moreover, the inclusion of 15% Sr in BaTiO3 increases the apparent porosity and water absorption of the sample to 6.2 and 28.5%, respectively. The optical properties were investigated by Ultraviolet–visible spectroscopy and it was found that the optical band gap decreases significantly with increasing Sr concentration, from 3.10 for pure BaTiO3 to 2.46 eV for the BSr30%T compound. The thermal conductivity measurements showed that the doping mechanism and the increased temperature have a significant effect on the thermal conductivity results of the fabricated ceramic materials. Therefore, it was found that the value of thermal conductivity increases with increasing Sr doping and at higher temperatures. A correlated behavior of optimum values is observed in band gap energy, absorption, and thermal conductivity which can be exploited for thermo-optical applications.

The two-dimensional electron gas (2DEG) density modeling in WZ strained InN/GaN hetero-interface with Ga-face arrangement is considered in this paper. We theoretically investigate the role of an externally applied hydrostatic pressure and impurity's position by analyzing their impact in the presence of built electric field due to the dielectric mismatch between the system and its surrounding matrix. To solve the coupling Schrodinger-Poisson equations, as well as the polarization induced charges, finite element method code is used. Pressure-dependence of dielectric constant, band-gap energy, lattices and internal electric field is considered. The 2DEG appears to be strongly-dependent internal and external perturbations exhibiting a non-monotonic behavior. Our results prove that: (1) the InN channel is more populated for on-center impurity compared to off-center one, (2) the electron density in the triangular shape quantum well increases with the pressure; (3) the 2DEG density is enhanced versus the positive impurity's position and dropped versus pressure.