R3c to P1 phase transition in Nd3+/Gd3+ co-doped BiFeO3 nanoparticles: Enhanced magnetic and photocatalytic properties

Abstract

We successfully synthesized pure and Nd3+/Gd3+ co-doped BiFeO<inf>3</inf> nanoparticles (NPs) via the sol–gel route. X-ray diffraction (XRD) and Raman spectroscopy studies indicates that co-doping at the Bi3+ sites triggered a structural phase transition from rhombohedral (R3c) to triclinic (P1). Also resulted in a decrease in particle size from 41 nm to 33 nm. XPS analysis confirmed successful Nd3+/Gd3+ co-doping in BiFeO<inf>3</inf> NPs and reveals the presence of Fe2+ ions. The optical band gap of doped NPs decreased significantly from 2.10 to 1.94 eV. Magnetization measurements revealed a significant enhancement in magnetization values under an applied field of 50 kOe, reaching 1.70 emu/g, a 300 % increase compared to pure BiFeO<inf>3</inf> due to the suppression of the spiral spin structure, suggests potential application for spintronics. Nd3+/Gd3+ co-doped BiFeO<inf>3</inf> NPs showed remarkable photocatalytic activity, degrading 99 % of methylene blue dye under sunlight irradiation in just 90 min as compared to BiFeO<inf>3</inf> NPs. © 2025 Elsevier B.V.