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Abstract: Nano-structure pure barium titanate (BaTiO3) and that was doped with iron oxide (Fe2O3), have been prepared by sol–gel method, using barium acetate (Ba(Ac)2) and titanium butoxide (Ti(C4H9O)4), as precursors. The as-grown prepared samples by sol–gel technique were found to be amorphous, which crystallized to the tetragonal phase after synthesized at 750°C in air for 1h as detected from the XRD patterns. The XRD data were confirmed by transmission electron microscope (TEM). The dielectric properties namely; dielectric constant (ε′) and loss tangent (tan δ) in the frequency range between 42Hz and 1MHz, at range of temperature 25–250°C were investigated. The temperature dependence of ε′ and tan δ for the undoped and doped materials, at 1kHz, was also investigated. As a result, tan δ increased rapidly with decreasing temperature below 125°C (Curie temperature) while above this temperature, tan δ shows temperature independent. As a result, below and above Curie temperature, ferroelectric phase and paraelectric phase of BaTiO3 can be obtained, respectively. [Copyright &y& Elsevier]

Abstract: Nano-composite Ba1−x Sr(x)TiO3 (BST), where x=0.01–0.50 and doped with different concentrations of iron Ba(1−x−y)Sr(x)TiFe (y)O3 (BSTF), where x=0.01 and y=0.01–0.05 powders were prepared by sol–gel method. The effect of increasing the iron and strontium concentrations substituted in Barium strontium titanate system will be studied. The prepared samples have a tetragonal crystalline phase after sintering for 1h at 750°C in air. The structural and the morphological features of the systems have been studied using X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). The dielectric properties of the BST and BSTF systems have been investigated as a function of temperature and frequency. The dielectric measurements are carried out in the frequency range 42Hz–1MHz, at a temperature ranging between 25 and 250°C. The results showed a decrease in T c temperature giving the following values 90 and 85°C for B10ST and B10ST5F prepared powder samples, respectively, implying tetragonal, feroelectric phase at lower temperature into cubic, para-electric phase at temperature higher than T c . [Copyright &y& Elsevier]