Magnetic and magnetocaloric properties of rare-earth substituted Gd2O3 nanorods

Abstract

Nanorods of Gd2O3 with 5 at.% Nd3+ and 5 at.% Er3+ ion substitution at Gd-site have been synthesized using a template-free and surfactant-free hydrothermal method. The samples have MnFeO3-type cubic crystal structure (space group Ia-3, N 206, cI80) at 300 K. Using the powder X-ray diffraction data and Scherrer formula, a crystallite size of ∼25 nm and ∼20 nm is estimated for the Nd-substituted and Er-substituted Gd2O3 nanorod samples. Raman spectrum also confirms the cubic structure of the samples at 300 K. Both samples show paramagnetic behaviour in the temperature range of 300 K to 5 K. From the magnetization vs field data measured in the temperature range of 5 K to 31 K, the isothermal magnetic entropy change (ΔSm) is calculated. The maximum ΔSm value at 6 K for 70 kOe field change is about −19.8 Jkg−1K−1 and −23.5 Jkg−1K−1 respectively for 5 at.% Nd- and Er- substituted Gd2O3 nanorods. The magnetocaloric effect is large and is of the same order as in the pure and other rare-earth-substituted Gd2O3 nanostructures. Thus the mixed rare-earth oxide nanostructures are found to be potential candidates for low temperature magnetic cooling applications.