J.H. Yang

A study of structural, optical and magnetic properties of Cr, Ce co-doping in ZnO diluted magnetic semiconductors

We present the structural, optical and magnetic properties of pure ZnO, Zn0.97Cr0.03O and Zn0.96Cr0.03Ce0.01O samples, the samples were synthesized by sol–gel method. The microstructures, optical and magnetic properties of samples were investigated by X-ray diffraction (XRD), transmission electron microscope , X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), Raman spectroscopy and vibrating sample magnetometer. XRD and XPS data confirmed the formation of a single phase wurtzite type ZnO structure for all the samples. PL measurements revealed that all the three samples had an UV emission and a defect emission, and the Ce ions doping induced a red shift in the UV emission and an increase in the defect emission. Zn0.97Cr0.03O and Zn0.96Cr0.03Ce0.01O samples showed the obvious hysteresis loops at room temperature and the saturation magnetization (Ms) increases with incorporating of Ce.

Effects of different sintering atmosphere on the structure and properties of Cu-doped ZnO powders prepared by sol–gel method

Cu-doped ZnO powders have been successfully synthesized by the sol–gel method in different sintering atmospheres, including argon and air, respectively. The effects of the sintering atmosphere on the structure, magnetic and optical properties of Cu-doped ZnO were investigated in detail by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, vibrating sample magnetometer and photoluminescence measurements. The results showed that the Cu-doped ZnO powders sintered in Ar had a hexagonal wurtzite structure without any secondary phase, however, CuO was observed in the sample sintered in air. From the magnetic and photoluminescence spectra, it could be seen that the sintering atmospheres strongly influenced the magnetic and optical properties of the powders.

Enhancement of magnetization in Er doped BiFeO3 thin Film

Pure BiFeO3 and Er-doped BiFeO3 (Bi0.9Er0.1FeO3) thin films were successfully fabricated on cleaned Si (100) substrates by a simple spin-coating processing. X-ray diffraction and Raman spectroscopy indicated the substitutions of Er into the Bi site and a change in crystal structure in Bi0.9Er0.1FeO3 thin film. Scanning electron microscope and transmission electron microscope were used to analyze the morphologies and microstructures of the thin films. X-ray photoemission spectroscopy result indicated that the oxidation state of Fe ion was Fe3+ in the Bi0.9Er0.1FeO3 thin film without detectable Fe2+. In comparison with the BiFeO3 thin film studied here, the Bi0.9Er0.1FeO3 thin film showed the surprising remnant magnetization and saturation magnetization. The remnant magnetization of Bi0.9Er0.1FeO3 thin film was nearly 5 times as large as that of BiFeO3 thin film. Moreover, the possible reasons for the enhancement of magnetization were discussed in detail. These results will have some implications for further research.