Phase Stability of Lanthanum Orthovanadate at High Pressure

Errandonea, Daniel; Pellicer‐Porres, J.; Martínez‐García, D.; Ruiz‐Fuertes, J.; Friedrich, Alexandra; Morgenroth, Wolfgang; Popescu, Cătălin; Rodríguez‐Hernández, P.; Múñoz, A.; Bettinelli, Marco

doi:10.1021/acs.jpcc.6b04782

Cited by 46 publications

(110 citation statements)

References 77 publications

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“…The number of Raman-active modes detected for this HP phase of MnWO 4 is 18 (the same number as that for the wolframite-type phase). These modes have been assigned in accordance with the crystal structure proposed for the HP phase [13,31]. This structure is a triclinic distortion of wolframite, and the same number of Raman-active modes is expected; however, all of them have A g symmetry in the HP phase.…”

Section: Modesupporting

confidence: 73%

“…In the figure, it can be seen that the frequency distribution (and intensity) of the Raman-active modes is qualitatively similar in CdWO 4 , ZnWO 4 , MnWO 4 , and MgWO 4 . Since Raman-active vibrations correspond either to A g or B g modes, polarized Raman scattering and selection rules can be combined to identify the symmetry of modes [30,31]. The expected 18 Raman modes have been measured for CdWO 4 , ZnWO 4 , MnWO 4 , and MgWO 4 , and 15 modes for CoWO 4 , FeWO 4 , and NiWO 4 .…”

Section: Raman Spectroscopymentioning

confidence: 99%

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A Brief Review of the Effects of Pressure on Wolframite-Type Oxides

Errandonea

Ruiz‐Fuertes

2018

Crystals

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Abstract:In this article, we review the advances that have been made on the understanding of the high-pressure (HP) structural, vibrational, and electronic properties of wolframite-type oxides since the first works in the early 1990s. Mainly tungstates, which are the best known wolframites, but also tantalates and niobates, with an isomorphic ambient-pressure wolframite structure, have been included in this review. Apart from estimating the bulk moduli of all known wolframites, the cation-oxygen bond distances and their change with pressure have been correlated with their compressibility. The composition variations of all wolframites have been employed to understand their different structural phase transitions to post-wolframite structures as a response to high pressure. The number of Raman modes and the changes in the band-gap energy have also been analyzed in the basis of these compositional differences. The reviewed results are relevant for both fundamental science and for the development of wolframites as scintillating detectors. The possible next research avenues of wolframites under compression have also been evaluated.

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Section: Modesupporting

confidence: 73%

Section: Raman Spectroscopymentioning

confidence: 99%

A Brief Review of the Effects of Pressure on Wolframite-Type Oxides

Errandonea

Ruiz‐Fuertes

2018

Crystals

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“…The number of Raman-active modes detected for this HP phase of MnWO4 is eighteen (the same number than in the wolframite-type phase). These modes have been assigned in accordance with the crystal structure proposed for the HP phase [13,31].…”

Section: Raman Spectroscopysupporting

confidence: 58%

“…In the figure, it can be seen that the frequency distribution (and intensity) of the Raman-active modes is qualitatively similar in CdWO4, ZnWO4, MnWO4, and MgWO4. Since Raman-active vibrations correspond either to Ag or Bg modes, polarized Raman scattering and selection rules can be combined to identify the symmetry of modes [30,31]. The expected eighteen Raman modes have been measured for CdWO4, ZnWO4, MnWO4, and MgWO4 and fifteen modes for CoWO4, FeWO4, and NiWO4.…”

Section: Raman Spectroscopymentioning

confidence: 99%

Brief Review of the Effects of Pressure on Wolframite-Type Oxides

Errandonea¹,

Ruiz‐Fuertes²

2018

Preprint

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“…25 This methodology has been previously applied successfully to the study of several ternary oxides under HP conditions. 26,27 Finally, the electronic band structure and density of states have been also calculated for the different polymorphs of MgSO 4 . The obtained values for the band-gap energy (E g ) should be considered as a lower boundary for it due to the well-known tendency of GGA to slightly underestimate E g .…”

Section: Methodsmentioning

confidence: 99%

New pressure-induced polymorphic transitions of anhydrous magnesium sulfate

et al. 2017

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Abstract:The effects of pressure on the crystal structure of the three known polymorphs of magnesium sulfate (α-MgSO 4 , β-MgSO 4 , and γ-MgSO 4 ) have been theoretically study by means of density-functional theory calculations up to 45 GPa. We determined that at ambient conditions γ-MgSO 4 is an unstable polymorph, which decompose into MgO + SO 3 , and that the response of the other two polymorphs to hydrostatic pressure is non-isotropic.Additionally we found that at all pressures β-MgSO 4 has a largest enthalpy than α-MgSO 4 .This indicates that β-MgSO 4 is thermodynamically unstable versus α-MgSO 4 and predicts the occurrence of a β−α phase transition under moderate compression. Our calculations also predict the existence under pressure of additional phase transitions to two new polymorphs of MgSO 4 , which we named as δ-MgSO 4 and ε-MgSO 4 . The α−δ transition is predicted to occur at 17.5 GPa, and the δ−ε transition at 35 GPa, pressures that nowadays can be 2 experimentally easily achieved. All the predicted structural transformations are characterized as first-order transitions. This suggests that they can be non-reversible, and therefore the new polymorphs could be recovered as metastable polymorphs at ambient conditions. The crystal structure of the two new polymorphs is reported. In them, the coordination number of sulfur is four as in the previously known polymorphs, but the coordination number of magnesium is eight instead of six. In the article we will report the axial and bond compressibility for the four polymorphs of MgSO 4 . The pressure-volume equation of state of each phase is also given, which is described by a third-order Birch-Murnaghan equation. The values obtained for the bulk modulus are 62 GPa, 57 GPa, 102 GPa, and 119 GPa for α-MgSO 4 , β-MgSO 4 , δ-MgSO 4 , and ε-MgSO 4 , respectively. Finally, the electronic band structure of these four polymorphs of MgSO 4 has been calculated by the first time. The obtained results will be presented and discussed.

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Phase Stability of Lanthanum Orthovanadate at High Pressure

Cited by 46 publications

References 77 publications

A Brief Review of the Effects of Pressure on Wolframite-Type Oxides

A Brief Review of the Effects of Pressure on Wolframite-Type Oxides

Brief Review of the Effects of Pressure on Wolframite-Type Oxides

New pressure-induced polymorphic transitions of anhydrous magnesium sulfate

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