Local structure and paramagnetic properties of ZnMn O

Having based on x-ray absorption spectroscopy, we point out structural phase separation in polycrystalline ZnMnO ceramics prepared by solid-state reaction. The samples are single phase in the wurtzite structure as x < 0.04. A Mn-concentration increase with x ≥ 0.04 results in the formation of a secondary phase of tetragonal ZnMnO spinel. The feature of x-ray absorption spectra for the Mn K edge reveals an existence of Mn and Mn ions in Zn MnO, which are responsible for room-temperature paramagnetism. Particularly, when Mn content is increased, there is a chemical shift of the absorption edge toward higher energies, indicating an increase in concentration of Mn ions. Fourier analyses for the spectra of extended x-ray absorption fine structure (EXAFS) shows up the substitution of Mn for Zn sites in the ZnO host lattice. The parameters related to the local structure have been determined and discussed in detail. © 2011 American Institute of Physics.