Here, we reported a characterization of the high-pressure structural and vibrational behavior of three metal iodates (Co, Zn and Fe). A series general features have been found by the combination of x-ray diffraction, Raman spectroscopy, Infrared spectroscopy and first-principles calculations. we have found evidence of two subtle isosymmetric structural phase transitions and presented 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.
Pablo Martínez Reviriego