Study of sodium citrate dependent crystalline orientation and properties of Zn0.85Co0.05Mg0.10O films

Zn0.85Co0.05Mg0.10O (ZCMO) films with different morphologies have been prepared by a low temperature hydrothermal method via changing sodium citrate (Na3Cit) concentration in the source solutions, which have been investigated on their structural, optical and magnetic properties. With continuously increasing Na3Cit concentration in the source solutions, these films derived from the solutions changed their morphologies from aligned nanorods to the rose flower-like crystals vertical to the substrate and preferential orientation from [0 0 0 1] to [101¯0] direction which were characterized by scan electron microscope (SEM) and X-ray diffraction (XRD) respectively. It was also found that the bandgaps of the ZCMO films obtained from transmittance spectra enlarge with the increase of the Na3Cit concentration in the source solutions. A strong and wide visible emission band centering at about 460 nm and the ferromagnetism were observed for all ZCMO films at room temperature, the intensities of which change with the variation of Na3Cit concentration in the source solutions. The change of bandgaps and the origins of the visible emission and the ferromagnetism were also discussed.