Structural, thermal, optical, and magnetic behavior of the nanosized perovskite-like GdFeO3 synthesized by modified co-precipitation method

Abstract

GdFeO₃ nanoparticles were synthesized using an improved co-precipitation method using a 5% ammonium hydrogen carbonate solution, followed by annealing for 1 h at 750, 850, and 950 °C. The synthesized samples were characterized using DSC/TGA, FTIR, PXRD, TEM, EDX/EDX-mapping, UV–Vis, and VSM analyses. The DSC curve exhibited two endothermic peaks (70.45 and 141.30 °C) and three exothermic peaks (333.01, 480.93, and 723.41 °C), while TGA analysis indicated that mass loss ceased at approximately 750 °C. PXRD patterns of all calcined samples confirmed a perovskite structure with space group Pbnm, and the average crystalline size and lattice volume increased with rising annealing temperatures. TEM images revealed that the synthesized GdFeO₃ nanoparticles were weakly angular spherical particles ranging from approximately 20–55 nm. Magnetic analysis showed that the GdFeO₃ orthoferrite nanopowder exhibited paramagnetic behavior, with net magnetization (M_n ~ 1.4 – 2.0 emu·g⁻¹) increasing with calcination temperature while maintaining negligible remanence and coercivity. Additionally, the nanoparticles displayed strong optical absorption in the UV (λ ~ 200 – 400 nm) and visible (λ ~ 400 – 600 nm) regions. Compared to certain reported RFeO₃ perovskites (R = Gd, Nd, Y, La, Ho), the synthesized GdFeO₃ nanopowder demonstrated both higher magnetization and a significantly lower band gap energy.