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Strontium‐modified barium titanate ceramics with the compositional formula Ba1−xSrxTiO3 (barium strontium titanate, BSrxT) with (x = 0, 0.05, 0.125, 0.15, 0.20, and 0.3) have been synthesized through sol‐gel method. X‐ray diffraction (XRD) patterns of the as‐prepared ceramics, calcined at a relatively low temperature (950 °C/3 h), reveal that BSrxT ceramics possess tetragonal structure in the range of x = 0–20% and shift into a cubic structure at high Sr composition (x = 30%). Based on XRD and Fourier‐transform infrared spectroscopy analysis, the occupation of the Ba and/or Ti sites by strontium in the BaTiO3 system and the behaviors of the crystalline parameters as functions of the Sr content have been discussed. The scanning electron microscopy shows that the grain size and densification sensitively depend on the Sr content. The study of the thermal conductivity measurements performed on the as‐prepared ceramics reveals the influence of Sr content on the thermal conductivity value. However, the microstructure of BSrxT impacts the compressive strength, therefore, the value of the latter is found to be decreased when the grain size increased.

In this study the preparation of pure and Bismuth (Bi) doped barium titanate (BaTiO3) nanoceramics by sol-gel process is reported. The structural and optical properties of the samples were investigated using X-ray diffraction (XRD) and UV-visible spectroscopy. XRD results show that the samples are crystallized in the pure perovskite structure when calcined at relatively low temperature (800 °C) for 3 h, without the presence of secondary phases. Both Bi doping (1%, 2%) decrease the lattice parameters, tetragonality and the crystallite size. The decrease of their sizes can be explained by the replacement of large ionic radii of Ba2+ (1.35Å) ion by smaller ionic radii Bi3+ (1.03 Å) ion. A close investigation of the results shows that BT is a tetragonal-phase ferroelectric. The band gap of the Bi-doped BaTiO3 nanopowders is lower compared to that of pure BaTiO3, as determined from the analysis of UV absorbance spectra.

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Yttrium (Y) modified strontium titanate (SrTiO3) powders with initial concentration of Y in the range of 0 to 15 mol% were produced through sol-gel technique. X-ray diffraction (XRD) studies show that all the prepared compounds have a perovskite cubic structure with the space group (Pm3m). The lattice constant, lattice strain and crystallite size of the as-prepared samples were estimated from the XRD pattern which reveals the incorporation of Y into SrTiO3 system, moreover to investigate the quality of the prepared SrYT ceramics powder, the scanning electron microscopy (SEM) was used to determined investigate the morphology, grain size and its distribution. The analysis of the thermal conductivity measurements performed on the obtained powders revealed the effect of the combination of temperature and Y content on the thermal conductivity value, Indeed, the minimum thermal conductivity was 4.12 W/(mK) obtained with 15%Y at 464 K.