Synchrotron X-ray study of polycrystalline wurtzite Zn1-xMgxO (0 <= x <= 0.15): Evolution of crystal structure and polarization

TL;DR

This study investigates how magnesium substitution affects the crystal structure, polarization, and optical properties of polycrystalline wurtzite ZnO, revealing structural compression, polarization reduction, and band gap widening with increasing Mg content.

Contribution

It provides detailed synchrotron X-ray diffraction analysis of Mg-doped ZnO, highlighting structural and polarization changes not previously characterized.

Findings

Mg substitution causes c-axis compression in ZnO.

Polarization decreases with Mg content.

Band gap increases from 3.24 eV to 3.35 eV.

Abstract

The effect of Mg-substitution on the crystal structure of wurtzite ZnO is presented based on synchrotron X-ray diffraction studies of polycrystalline Zn1-xMgxO (0 <= 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 ZnO4 unit. Going from ZnO to Zn0.85Mg0.15O, significant changes in the ionic polarization are observed (-5.6 to -4.8 uC/cm2), despite only subtle increments in the cell volume (~0.03 %) and the ab-area dimension (~0.1 %). The optical properties of the samples have also been characterized and the band gap changes from 3.24 eV (ZnO) to 3.35 eV (Zn0.85Mg0.15O).