Magnetic defects in crystalline Zn(OH)2 and nanocrystalline ZnO resulting from its thermal decomposition

Abstract: Trace amounts of substitutional Mn2+ ions and shallow donors magnetic centers were identified by electron paramagnetic resonance (EPR) in crystalline Zn(OH)2 prepared by precipitation of a Zn-nitrate solution with NaOH. Strong changes in the Mn2+ ions spectrum, as well as a sharp increase in the concentration of the shallow donor centers were observed by EPR in the 110–140°C temperature range, during pulse annealing experiments in air up to 240°C. They reflect the decomposition of the crystalline Zn(OH)2 host lattice into nanocrystalline ZnO, confirmed by X-ray diffraction and thermal analysis measurements. Accurate spin Hamiltonian parameters of the observed paramagnetic centers were determined by lineshape simulation and fitting of the EPR spectra, to be used as reference data in further studies of nanocrystalline systems involving Zn(OH)2. [Copyright &y& Elsevier]