Study of variation in physical properties of KBiFe2O5 prepared by different synthesis routes and heat treatments

The influence of different synthesis routes and the heat treatments on the fundamental physical properties of the potassium bismuth ferrite oxide KBiFe2O5 (KBFO) is investigated. The polycrystalline KBFO is prepared using a solid-state reaction route followed by conventional heating (SSR) and the sol–gel method followed by conventional heating (SGC) and microwave heating (SGM). The monoclinic phase of the prepared sample is confirmed from the Rietveld refined X-ray diffraction analysis. XRD confirms crystallite size decrease from SSR (165 nm) to SGM (91 nm) sample. The surface morphology reveals that grain size varies from 4 µm (SSR) to 100 nm (SGM). The observed variation in Raman intensity and FWHM indicates the effect of different synthesis routes on the particle sizes of KBFO. The optical energy band gap increases from 1.59 eV (SSR) to 1.73 eV (SGM) with changes in the synthesis route and heat treatment. Temperature-dependent dielectric (25 °C to 560 °C) data at 1 MHz frequency shows a significant variation in dielectric value followed by a transition at 510 °C (TC) in all the prepared samples. The dielectric value of the SSR sample almost 50 times larger than the SGC and SGM samples of KBFO.