Study of a Complex Double Perovskite CaKFeWO6: Enhanced Dielectric, Transport, Thermistor, and Optical Properties for Energy Storage Applications

The novel complex perovskite CaKFeWO6 prepared by the solid-state reaction method has been reported in this communication. Structural, surface analysis, dielectric and electrical (both at low and high temperatures), transport, thermistor, and optical characterization of the prepared polycrystalline material were discussed in the study. Monoclinic structure with a crystallite size of 59 nm was well analyzed from the X-ray diffraction data. Surface study from microstructural data reveals a good and dense distribution of grains. Raman spectroscopy reflects peaks at the corresponding vibrational modes of the synthesized sample. Optical properties investigated from the optical absorbance measurements provide narrow bandgap energy quite suitable for photocatalytic applications. Colossal dielectric constant with low loss at room temperature from dielectric data and relaxation nature from dielectric loss and modulus plots indicate a good potential candidate for capacitor-based applications. The (R(g)Q(g)) (R(gb)Q(gb)) data acquired from theoretically fitted Nyquist plot (using the ZSIMPWIN software 2.0) reflects a negative temperature coefficient resistance (NTCR) nature and hence supports the semiconducting properties of the sample. High DC conductivity due to grain at high frequency and temperature is a typical value of semiconductors. A small difference in the activation energy of AC and DC conductivity indicates the involvement of the same charges both in grain and grain boundaries. Minor oxygen vacancies and long-range conduction mechanisms enhance its probability as a suitable candidate for application in electronic industries. A suitable value of thermistor constant (beta) within the applicable range also makes the material consistent for thermistor-related applications.