Synchrotron x-ray study of polycrystalline wurtzite Zn1−xMgxO (⩽x⩽0.15): Evolution of crystal structure and polarization

Abstract

The effect of Mg substitution on the crystal structure of wurtzite ZnO is presented based on synchrotron x-ray diffraction studies of polycrystalline ${\mathrm{Zn}}_{1-x}{\mathrm{Mg}}_x\mathrm{O}$ $(⩽x⩽0.15)$ . Increase in Mg concentration results in pronounced $c$ -axis compression of the hexagonal lattice, and in diminution of the off-center cation displacement within each tetrahedral $\mathrm{Zn}{\mathrm{O}}_4$ unit. Going from ZnO to ${\mathrm{Zn}}_{0.85}{\mathrm{Mg}}_{0.15}\mathrm{O}$ , significant changes in the ionic polarization are observed $(-5.6\text{to}-4.8\mu \mathrm{C}∕{\mathrm{cm}}^2)$ , despite only subtle increments in the cell volume $(\sim 0.03\%)$ and the $ab$ -area dimension $(\sim 0.1\%)$ .