Unveiling the role of the lone electron pair in sesquioxides at high pressure: compressibility of β-Sb2O3.

摘要: The structural, vibrational and electronic properties of the compressed β-Sb2O3 polymorph, a.k.a. mineral valentinite, have been investigated in a joint experimental theoretical study up to 23 GPa. compressibility lattice parameters, unit-cell volume polyhedral unit as well behaviour its Raman- IR-active modes under compression interpreted on basis ab initio simulations. Valentinite shows an unusual 15 GPa with four different pressure ranges, whose critical pressures are 2, 4, 10 dependence main structural units, lack soft phonons, density charge topology address changes at those isostructural phase transitions degree higher than 2. In particular, 2 4 can be ascribed interaction between stereochemically-active lone electron pairs Sb atoms compression. observed above GPa, characterized by general softening several modes, point instability prior 1st-order transition occurring Above this pressure, tentative new high-pressure (s.g. Pcc2) has assigned single-crystal powder X-ray diffraction measurements.