Comparative Study of the Compressibility of M3V2O8 (M = Cd, Zn, Mg, Ni) Orthovanadates

Abstract

We report herein a theoretical study of the high-pressure compressibility of Cd3V2O8, Zn3V2O8, Mg3V2O8, and Ni3V2O8. For Cd3V2O8, we also present a study of its structural stability. Computer simulations were performed by means of first-principles methods using the CRYSTAL program. In Cd3V2O8, we found a previously unreported polymorph which is thermodynamically more stable than the already known polymorph. We also determined the compressibility of all compounds and evaluated the different contributions of polyhedral units to compressibility. We found that the studied vanadates have an anisotropic response to compression and that the change in volume is basically determined by the compressibility of the divalent-cation coordination polyhedra. A systematic discussion of the bulk modulus of M3V2O8 orthovanadates will also be included.

High-Pressure Vibrational and Structural Properties of Ni3V2O8 and Co3V2O8 up to 20 GPa

“…The region used for the fits is from 0.0(1) to 9.3(1) GPa to guarantee that only hydrostatic data are used. When these compressibilities are compared with the experimentally obtained ones for Ni 3 V 2 O 8 and simulated for other orthovanadates, it can be clearly appreciated that they follow the same behavior followed for this family of compounds, but the b -axis of Co 3 V 2 O 8 is slightly more compressible. Once more, this can be related to the “compressed” structure of Ni 3 V 2 O 8 indicated in Section , since the b -axis is mainly influenced by the layers of CoO 6 octahedra (see Figure ), which are more compressible than the NiO 6 octahedra.…”

Stability of FeVO4-II under Pressure: A First-Principles Study

“…In this case, the maximum at Γ below the Fermi level is occupied by 2p (p x and p y ) states from oxygen, as happens in other ABO 4 compounds [40]. It has been reported that CBM of many rare-earth AVO 4 vanadates is dominated by vanadium 3d states, which makes these compounds present energy band-gaps close to 3.8 eV [50,51]. However, in the case of vanadates InVO 4 (phase II), CrVO 4 (phase II), and FeVO 4 (phase I), the energy band-gap lowers to 3.2, 2.6, and 2.1 eV, respectively, due to contribution from cation A to the valence and conduction band [5,6,50,52].…”

Remote Steric Control of the Tetrahedral Coordination Geometry around Heteroleptic Copper(I) Bis(Diimine) Complexes

“…The calculations were performed with the ADF 2019 package at DFT level of theory using the B3LYP functional (Becke-3-Lee-Yang-Parr) [ 43 , 44 ]. Scalar relativistic effects were included using zero-order regular approximated (ZORA) Hamiltonian [ 45 ].…”