Creation of RT-FM in CdO nanocrystalline powder by codoping with Cu and Gd: Effect of annealing in hydrogen atmosphere

Abstract

Cadmium oxide codoped with Cu and Gd ions powders were synthesised by simultaneous thermal co-decomposition of a mixture of cadmium acetate dihydrate, bis(acetylacetonato)copper, and tris(acetylacetonato)gadolinium(III) complexes. The mass ratio of Cu/Cd is fixed while the Gd/Cd mass ratio varied systematically. The purpose of the present study is to prepare powders having room temperature ferromagnetic (RT-FM) properties. Thus, an amount from each powder was annealed in hydrogen atmosphere in order to study its influence on the magnetic properties. X-ray fluorescence (XRF) and X-ray diffraction (XRD) methods confirm the purity and the formation of single nanocrystalline structure of the as-prepared powders, thus, both Cu and Gd ions were incorporated into CdO lattice forming solid solutions. Magnetic measurements reveal that all doped CdO powders gained paramagnetic (PM) properties where the susceptibility increases linearly with increasing dopant Gd content; the measured effective magnetic moment of doped Gd3+ was 7μB. Furthermore, the created RT-FM is dependent on the Gd% doping level. Also, it was found that the hydrogenation of the powders slightly enhances their PM properties and strongly enhances or creates RT-FM. For hydrogenated CdO powder doped with 3.1% Gd, the coercivity (Hc), remanence (Mr), and saturation magnetization (Ms) were 283.2Oe, 2.04memu/g, and 6.67memu/g, respectively. Also, under hydrogenation, the values of Hc, Mr, and Ms were increased by ∼145%, 476%, and 131%, respectively in comparison with as prepared. Thus it was proved, for the first time, the possibility of production of CdO with RT-FM, where magnetic characteristics can be tailored by doping and post treatment under H2 atmosphere, thus a new potential candidate to be used as a dilute magnetic semiconductor (DMS).