Abstract: A polyacrylamide gel method was used to prepare TbFeO₃ nanoparticles, and the influences of diffe-rent chelating agents on the phase purity, particle size and morphology were investigated. X-ray diffraction(XRD) results indicate that single-phase TbFeO₃ particles can be prepared at a calcination temperature of 650 ℃ using tartaric acid, citric acid or ethylenediamine-tetraacetic acid(EDTA) as the chelating agent, but the average grain size has a dependence on the choice of the chelating agent. The use of acetic acid or oxalic acid as the chelating agent is difficult to achieve the synthesis of single-phase TbFeO₃ samples. Scanning electron microscope(SEM) observations reveal that the particles prepared using tartaric acid as the chelating agent are regularly spherical in shape and highly uniform in size with a small average diameter of ca. 50 nm; the particles prepared using citric acid as the chelating agent mainly exhibit sphere-like shape and have a relatively broad size distribution with an average size of ca. 100 nm; and the particles prepared using the chelating agent EDTA are ellipsoid-like in shaped with adhesive behavior to some extent, but have a uniform size distribution with an average size of ca. 110 nm. The BET specific surface areas of the three samples are 15.4, 8.3 and 6.8 m²/g, respectively. Ultraviolet-visible diffuse reflectance absorption spectra indicate that the TbFeO₃ nanoparticles have a bandgap energy of 1.95-1.98 eV. The photocatalytic activity of the TbFeO₃ particles has been investigated by the degradation of various organic dyes including methyl orange(MO), rhodamine B(RhB), methylene blue(MB), acid fuchsine(AF), and congo red(CR). It is demonstrated that the products exhibit a pronounced photocatalytic activity under visible-light irradiation. The highest photocatalytic efficiency is observed for the tartaric acid-derived sample.

Key words: TbFeO₃, Nanoparticles, Polyacrylamide gel method, Chelating agent, Photocatalytic activity