Effect of Niobium Doping on Dielectric, Electrical and Magnetic Properties of Bismuth Copper Titanium Oxide

Abstract

Abstract: Bi<inf>2/3</inf>Cu<inf>3</inf>Ti<inf>4 –</inf><inf>x</inf>Nb<inf>x</inf>O<inf>12</inf> (BCTNO) ceramics with compositions x = 0.05, 0.10, and 0.20 were fabricated through a semi-wet route and sintered at 1173 K for 8 h. A detailed study was conducted to investigate the impact of Nb substitution on the structural, dielectric, electrical, and magnetic characteristics of BCTO. The synthesized Bi<inf>2/3</inf>Cu<inf>3</inf>Ti<inf>4 –</inf><inf>x</inf>Nb<inf>x</inf>O<inf>12</inf> (x = 0.05, 0.10, and 0.20) ceramics were designated as BCTNO-0.05, BCTNO-0.10, and BCTNO-0.20, respectively. X-ray diffraction (XRD) investigation highlights the presence of all characteristic peaks of the pure BCTO compound, confirming the development of a single phase with a well-defined crystal structure upon Nb doping up to a composition of 0.20. Furthermore, the lattice parameter of the synthesized compounds is found to decrease with increasing Nb concentration. Field emission scanning electron microscopy (FE-SEM) was employed to assess the microstructural alterations in the synthesized BCTNO ceramics. High resolution transmission electron microscopy (HR-TEM) images revealed that the BCTNO ceramics’ particle sizes varied from 189 to 191 nm. The valence states of various ions present in the Nb-doped BCTO ceramics were analysed utilizing X-ray photoelectron spectroscopy (XPS). The dielectric permittivity (εʹ) and tangent loss (tan δ) of BCTNO ceramics were found to decrease with rising frequency. Impedance analysis provided confirmation of thermally activated ionic conduction within the ceramics. The magnetization (M) vs. Magnetic field (H) studies revealed antiferromagnetic behaviour at low temperature, with indications of weak ferromagnetism. © Pleiades Publishing, Ltd. 2025.