Magnetocaloric effect of Gd2O3 nanorods with 5% Eu-substitution

Abstract

Abstract One dimensional Gd2O3 nanorods with 5% Eu substitution at Gd-site have been synthesized by a simple, inexpensive, hydrothermal process without using any catalyst or template. Structural, spectroscopic, magnetic and magnetocaloric properties of these nanorods are studied. Powder X-ray diffraction data confirm that these samples have cubic structure (Space group Ia-3) at 300 K. High resolution transmission electron microscopy images suggest the average diameter of nanorods to be ~14 nm. However, the rod length is found to vary from about 50 nm to 140 nm. Raman spectrum shows a peak at ~363 cm−1 as expected for the cubic phase of Gd2O3. The 5% Eu substituted Gd2O3 sample remains paramagnetic from 300 K down to 5 K. Using magnetization–field data obtained at various temperatures, isothermal magnetic entropy change (ΔSm) is calculated. The maximum ΔSm value at 6 K for 70 kOe field change is about −30.3 Jkg−1 K−1. This value is quite large compared to that of the pure Gd2O3 nanotube samples. Thus nanostructured Gd2O3 with small rare-earth substitution at Gd-site exhibit appreciable magnetocaloric effect and these nanomaterials may be suitable for low temperature magnetic refrigeration applications.