2008/08/04 by Young-Il Kim, Young‐Il Kim, Sylvian Cadars +6
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Atomic physics #Chemistry #Crystallography #Magnetic and transport properties of perovskites and related materials #Physics #ZnO doping and properties #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.78.195205
published as Phys. Rev. B 78, 195205 (2008) (12 pages) · 12 pages, 14 figures, 2 tables
arxiv created 2008/08/04 · openalex publication_date 2008/11/11 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Local compositions and structures of Zn_1\ensuremath-xMgxO alloys have been investigated by Raman and solid-state 67Zn/25Mg nuclear-magnetic-resonance (NMR) spectroscopies and by neutron pair-distribution-function (PDF) analyses. The E2low and E2high Raman modes of Zn_1\ensuremath-xMgxO display Gaussian- and Lorentzian-type profiles, respectively. At higher Mg substitutions, both modes become broader, while their peak positions shift in opposite directions. The evolution of Raman spectra from Zn_1\ensuremath-xMgxO solid solutions is discussed in terms of lattice deformation associated with the distinct coordination preferences of Zn and Mg. Solid-state magic-angle-spinning (MAS) NMR studies suggest that the local electronic environments of 67Zn in ZnO are only weakly modified by the 15% substitution of Mg for Zn. 25Mg MAS spectra of Zn0.85Mg0.15O show an unusual upfield shift, demonstrating the prominent shielding ability of Zn in the nearby oxidic coordination sphere. Neutron PDF analyses of Zn0.875Mg0.125O using a 2\ifmmode×\else\texttimes\fi2\ifmmode×\else\texttimes\fi1 supercell corresponding to Zn7MgO8 suggest that the mean local geometry of MgO4 fragments concurs with previous density-functional-theory-based structural relaxations of hexagonal wurtzite MgO. MgO4 tetrahedra are markedly compressed along their c axes and are smaller in volume than ZnO4 units by \ensuremath≈6%. Mg atoms in Zn_1\ensuremath-xMgxO have a shorter bond to the c-axial oxygen atom than to the three lateral oxygen atoms, which is distinct from the coordination of Zn. The precise structure, both local and average, of Zn0.875Mg0.125O obtained from time-of-flight total neutron scattering supports the view that Mg substitution in ZnO results in increased total spontaneous polarization.