Synthesis, Photoluminescence, and Magnetic Properties of Arrayed Al Doped Zn 0.95Co 0.05O Nanorods

Abstract

Arrayed Zn(subscript 0.95-x)AlxCo0.05O (ZnAlCoO for x=0.02-0.07 and ZnCoO for x=0) nanorods have been synthesized by a low temperature hydrothermal method and characterized as ZnO hexagonal structures by their X-ray diffraction (XRD) spectra, Raman spectra, and scanning electron microscopy (SEM), which show that Al doping can modulate the density and the cross section shape of the ZnCoO nanorods. Al and Co atoms substituting for Zn atoms in ZnAlCoO samples were successfully doped into a ZnO lattice, which has been characterized by X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectra. PL spectra exhibit that Al doping in ZnCoO markedly enhanced the visible light emission (VL) while it depressed the ultraviolet emission (UV). The positions of the UV peak first redshifted from 386 to 387 nm, then blueshifted to a shorter wavelength side (374 nm) with increasing Al doping concentration. Moreover, VL appears with redshifts and a maximum of intensity for the middle Al doping (x=0.04) sample. The high Al (x=0.07) doping sample exhibits room temperature ferromagnetism (RTFM) with saturation magnetization 20 times larger than that of the middle Al (x=0.04) doping sample while the low Al doping (x=0.02) sample exhibits no RTFM. The above structural, optical and magnetic phenomena are all discussed.