Studies on the structural, microstructure, dielectric, electrical and optical properties of Gd-doped BiFeO3 ceramic and its NTC thermistor application

Abstract

This study presents a comprehensive investigation of Gd-doped BiFeO₃ [Bi_0.9Gd_0.1FeO₃, BGFO] ceramics synthesized via a conventional solid-state reaction method. The preliminary structural Rietveld analysis confirms the formation of a rhombohedral structure (#Rc) with an average crystallite size of 65.5 nm, a micro-lattice strain of 0.00106, and a dislocation density of 2.33 × 10¹⁴ m⁻². The analysis of the FTIR spectrum confirms the presence of all atomic vibration bands in the studied sample. The analysis of UV visible data shows a wide bandgap energy of 2.9 eV, which may be suitable for applications in photodetectors, LEDs, etc. The study of dielectric properties versus frequency and temperature reveals that the studied sample has a high dielectric constant and low loss, making the material a better candidate for energy storage devices. The study of impedance plots versus frequency supports the semiconducting nature of the sample. The study of modulus plots versus frequency confirms the non-Debye type of relaxation mechanism. The study of the ac conductivity versus both frequency and temperature confirms a thermally activated hopping mechanism. Both the Nyquist and Cole–Cole plots support the semiconducting nature of the sample. Additionally, the material exhibits negative temperature coefficient (NTC) thermistor behavior, confirming its potential for temperature sensor applications.