Mn effect on wurtzite-to-cubic phase transformation in ZnO

Abstract

Mn doping effect on a wurtzite-to-cubic phase transformation in ZnO has been investigated by in situ high pressure X-ray powder diffraction using synchrotron radiation. Unit cell expansion is clearly observed in Mn-doped ZnO samples. Mn ions sit at Zn site in the wurtzite structure. The onset transition pressure for the wurtzite-to-cubic phase transformation decreases from about 9.5 GPa for pure ZnO to 6 GPa for sintered 2at.% Mn-doped ZnO while the compressibility and volume collapse at transition pressures are not sensitive to the Mn doping in the wurtzite phase. The doping of Mn ions in ZnO increases the onset transition pressure for the cubic-to-wurtzite phase transformation. The results could be explained by a reduction of phase transformation barriers for both transition paths by the Mn doping. The observation of reduction of the wurtzite-to-cubic phase transformation pressure might point out a new direction to synthesize cubic wurtzite phase of ZnO by doping transition element(s).