Cerium-modified Bi2FeMoO6: Microstructure, dielectric and optical properties

Abstract

This paper presents an extensive investigation into the synthesis and characterization of Bi2FeMo1-xCexO6 (x = 0.0, 0.06, and 0.1) double perovskite type ceramic materials, fabricated using a high-temperature solid-state reaction method. The article delves into various aspects of these materials, including their structural, microstructural, dielectric, and optical properties. Structurally, the materials exhibit a rhombohedral crystal structure, having average crystallite sizes of 49.5 nm, 21.8 nm, and 26.4 nm for the respective compositions. Scanning electron microscopy reveals a uniform distribution of cylindrical and fractured spherical-shaped grains, complemented by well-defined grain boundaries. Energy dispersive X-ray spectroscopy analysis and elemental color mapping provide concrete evidence regarding the presence of key elements, such as Bi, Fe, Mo, Ce, and O, affirming the formation of highly dense and pure samples. Dielectric properties are comprehensively characterized across a wide temperature range of 25 °C to 500 °C and frequency range of 1 kHz to 1 MHz, highlighting the occurrence of the Maxwell-Wagner polarization effect at lower frequencies. The impedance study underscores the pivotal role of both grains and grain boundaries in determining the conductivity mechanism, with the x = 0.1 composition exhibiting superior semiconducting characteristics. Further examination of the modulus study and AC conductivity supports this finding. Additionally, the calculation of thermal activation energy suggests that the x = 0.1 composition boasts a more favorable thermally activated relaxation mechanism, rendering it a promising candidate for various device applications. Finally, an assessment of the UV–visible spectra reveals that the x = 0.1 composition possesses an ideal bandgap energy range, making it particularly suited for advanced optoelectronic devices.