Synthesis, Crystal Structural and Electrical Conductivity Properties of Fe-Doped Zinc Oxide Powders at High Temperatures


JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY, vol.28, no.3, pp.268-274, 2012 (SCI-Expanded) identifier identifier


The synthesis, crystal structure and electrical conductivity properties of Fe-doped ZnO powders (in the range of 0.25-15 mol%) were reported in this paper. I-phase samples, which were indexed as single phase with a hexagonal (wurtzite) structure in the Fe-doped ZnO binary system, were determined by X-ray diffraction (XRD). The solubility limit of Fe in the ZnO lattice is 3 mol% at 950 degrees C. The above mixed phase was observed. And the impurity phase was determined as the cubic-ZnFe2O4 phase when compared with standard XRD data using the PDF program. This study focused on single I-phase ZnO samples which were synthesized at 950 degrees C because the limit of the solubility range is the widest at this temperature. The lattice parameters a and c of the I-phase decreased with Fe-doping concentration. The morphology of the I-phase samples was analyzed with a scanning electron microscope. The grain size of the I-phase samples increased with heat treatment and doping concentration. The electrical conductivity of the pure ZnO and single I-phase samples was investigated using the four-probe dc method at 100-950 degrees C in air atmosphere. The electrical conductivity values of pure ZnO, 0.25 and 3 mol% Fe-doped ZnO samples at 100 degrees C were 2x10(-6), 1.7x10(-3) and 6.3x10(-4), and at 950 degrees C they were 3.4, 8.5 and 4, respectively.