Critical role of hydrogenation for creation of magnetic Cd-Cu co-incorporated TiO2 nanocrystallites

Nanocomposite of titanium dioxide (TiO2) incorporated with cadmium/copper (Cd/Cu) ions was fabricated by the co-decomposition of a mixture of Ti, Cd, and Cu metal complexes. The crystalline structures were studied by the X-ray diffraction (XRD), which confirmed the formation of anatase and brookite mixture. The optical properties of the synthesized samples were measured by diffuse reflection spectroscopy (DRS). The bandgap red shift of host TiO2 due to Cd ions incorporation and blue shift due to Cu ions incorporation was detected and measured. The hydrogenation of the powder samples increased the carrier concentration and, thus blueshifted the bandgap. With the hydrogenation, all the synthesized samples, including undoped TiO2-acquired room temperature ferromagnetic (RT-FM) properties, which was attributed to the generation of oxygen (O) vacancies. The O-vacancies were reduced by extra annealing in air at 600 degrees C that eliminated the RT-FM. The magnetic measurements on Anatase/Brookite TiO2 nanocomposite doped with 3wt% Cd show a creation of a magnetic property with magnetic saturation of 7.6 memu/g, which increased to 13.1 memu/g with 1% Cu co-doping.