X-ray peak broadening analysis and dielectric studies of BCT ceramics; comparison of sol–gel and solid solution methods.

Abstract

In this study, nano- and micro- Ba1 − xCaxTiO3 powders (where x = 0, BT; 0.01, BCT1; 0.03, BCT3; and 0.05, BCT5) were synthesized through the sol–gel and solid-solution-reaction methods, respectively. The effects of synthesis methods and Ca concentrations on the prepared BCT samples’ structural and dielectric properties were subsequently investigated. The calcination temperature was 1000 °C based on thermogravimetric analysis results. In addition, X-ray diffraction (XRD) indicated a tetragonal phase for the samples. The XRD results were analyzed using Williamson-Hall and size strain plot methods to investigate the effect of calcium concentrations and synthesis methods on the strain and crystalline sizes of the BCT materials. Ca concentration increases were found to increase both uniform and non-uniform strains, whereas BCT-nano samples exhibited a significantly greater non-uniform strain than BCT micro samples. The grains and particle morphologies were studied by field emission scanning electron microscopy and transmission electron microscopy. It was observed that the particle size of the nanopowders was between 50 and 100 nm, and the grain sizes were between 20 and 40 μm. The prepared pellets’ relative permittivity (dielectric constant) variation at 1250 °C was measured and analyzed through the Curie-Weiss law. The results indicated that the ferroelectric behavior of BT was changed to relaxor behavior for BCT5.