Influence of the synthetic conditions on the crystal structure, magnetic and optical properties of holmium orthoferrite nanoparticles

In this work, holmium orthoferrite nanoparticles (o-HoFeO3) were prepared by a straightforward co-precipitation method and annealed at 850 °C for 60 min. The crystal structure, magnetic and optical properties of o-HoFeO3 samples were considerably different depending on the procedure used for co-precipitation of holmium and iron hydroxides. The hydrolysis of Ho (III) and Fe (III) cations in hot water (t° > 95 °C) increases the crystalline degree and reduces the particle size of the o-HoFeO3 phase compared with the control sample prepared at room temperature (t° ~ 27 °C). The prepared HoFeO3 nanoparticles are capable of getting used as photocatalyst materials because of their strong adsorption band at 200–400 nm observed from the UV–Vis spectrum. Additionally, the HoFeO3 nanoparticles are materials with Hc ~ 20–30 Oe, Mr ~ 0.01–0.02 emu·g−1, and Ms ~ 4.0–5.0 emu·g−1. These findings demonstrate their potential use not only as photocatalysts, but also as antiferromagnetic materials.