Barium Strontium Titanate (BST) solid solution is a strong candidate material for application in tunable ferroelectric devices. In this research, we have synthesized and characterized nanocrystalline BST (Ba 0.7 Sr 0.3 TiO 3 ) powder with average particle-diameter of 15 nm through a simple sol-gel process, using barium acetate, strontium acetate and titanium isopropoxide as the precursors. In this process, stoichiometric proportions of barium acetate and strontium acetate were dissolved in acetic acid followed by refluxing, and addition of titanium (IV) isopropoxide to form BST gel. The gel was analyzed using Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA). The as-formed gel was dried at 200°C and then calcined in the temperature range of 400 to 800°C for crystallization. Phase evolution during calcination was studied using X-ray diffraction (XRD) technique. Particle size, morphology and the lattice fringes of the calcined powder were characterized by high-resolution transmission electron microscopy (HR-TEM). To study the effects of sintering on BST nanopowder, green ceramic specimens were prepared by uniaxial compaction and then sintered at 950-1,100°C under atmospheric conditions. Sintered specimens were analyzed for phase composition, grain size and geometric bulk density.
Alumina–aluminum titanate–titania (Al2O3–Al2TiO5–TiO2) nanocomposites were synthesized using alkoxide precursor solutions. Thermal analysis provided information on phase evolution from the as‐synthesized gel with an increase in temperature. Calcination at 700°C led to the formation of an Al2O3–TiO2 nanocomposite, while at a higher temperature (1300°C) an Al2O3–Al2TiO5–TiO2 nanocomposite was formed. The nanocomposites were uniaxially compacted and sintered in a pressureless environment in air to study the densification behavior, grain growth, and phase evolution. The effects of nanosize particles on the crystal structure and densification of the nanocomposite have been discussed. The sintered nanocomposite structures were also characterized for dielectric properties.
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