Structural and vibrational study of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Zn</mml:mi><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mi mathvariant="normal">I</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>combining high-pressure experiments and density-functional theory
Akun Liang, Cătălin Popescu, F. J. Manjón, P. Rodríguez‐Hernández, Alfonso Muñoz, Zoulikha Hebboul, Daniel Errandonea
Abstract
We report a characterization of the high-pressure behavior of zinc iodate, $\mathrm{Zn}{(\mathrm{I}{\mathrm{O}}_{3})}_{2}$. By the combination of x-ray diffraction, Raman spectroscopy, and first-principles calculations we have found evidence of two subtle isosymmetric structural phase transitions. We present arguments relating these transitions to a nonlinear behavior of phonons and changes induced by pressure on the coordination sphere of the iodine atoms. This fact is explained as a consequence of the formation of metavalent bonding at high pressure which is favored by the lone-electron pairs of iodine. In addition, the pressure dependence of unit-cell parameters, volume, and bond distances is reported. An equation of state to describe the pressure dependence of the volume is presented, indicating that $\mathrm{Zn}{(\mathrm{I}{\mathrm{O}}_{3})}_{2}$ is the most compressible iodate among those studied up to now. Finally, phonon frequencies are reported together with their symmetry assignment and pressure dependence.