A combined high-pressure experimental and theoretical study of the electronic band-structure of scheelite-type AWO4 (A = Ca, Sr, Ba, Pb) compounds

Lacomba-Perales, R.; Errandonea, Daniel; Segura, A.; Ruiz‐Fuertes, J.; Rodríguez‐Hernández, P.; Radescu, S.; López-Solano, J.; Mújica, A.; Múñoz, A.

doi:10.1063/1.3622322

Cited by 85 publications

(62 citation statements)

References 42 publications

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“…The conclusions drawn from DFT calculation were very in accord with the experimental results that cyclohexyl hydroxamic acid exhibited better collecting ability than BHA to scheelite [11]. Density functional theory has also been proved to be an accurate tool to explore the physical and chemical properties of scheelite-type and wolframite-type oxides [12,13].…”

Section: Introductionsupporting

confidence: 75%

Study on the Activation of Scheelite and Wolframite by Lead Nitrate

2015

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Abstract:The activation of scheelite and wolframite by lead nitrate with benzohydroxamic acid (BHA) as collector was investigated by means of micro flotation test, zeta potential measurement, X-ray photoelectron spectroscopy (XPS) analyses and density functional theory (DFT) calculation. The flotation results confirmed that the addition of lead nitrate can markedly enhance the recovery of scheelite and wolframite. In the zeta potential curves obvious positive shifts were observed with the presence of lead nitrate. Lead was detected on mineral surface in microscopic analysis and the survey XP spectra. Both the electrokinetic study and XPS analyses indicated that lead ion can be adsorbed onto mineral surface. In DFT calculation, the coordination model of BHA with metal hydroxyl ions (Ca (

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Section: Introductionsupporting

confidence: 75%

Study on the Activation of Scheelite and Wolframite by Lead Nitrate

2015

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“…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 . [28][29][30] 3 Results and discussion…”

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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“…Measurements in the visible-near-IR range were made with an optical setup that consisted of a tungsten lamp, fused silica lenses, reflecting optics objectives, and a visible-near-IR spectrometer [35]. The optical-absorption spectra were obtained from the transmittance spectra of the sample, which were recorded using the sample-in, sample-out method [36,37].…”

Section: Methodsmentioning

confidence: 99%

Pressure-induced phase transition and band-gap collapse in the wide-band-gap semiconductorInTaO4

et al. 2016

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A pressure-induced phase transition, associated with an increase of the coordination number of In and Ta, is detected beyond 13 GPa in InTaO 4 by combining synchrotron x-ray diffraction and Raman measurements in a diamond-anvil cell with ab initio calculations. High-pressure optical-absorption measurements were also carried out. The high-pressure phase has a monoclinic structure that shares the same space group with the low-pressure phase (P 2/c). The structure of the high-pressure phase can be considered as a slight distortion of an orthorhombic structure described by space group Pcna. The phase transition occurs together with a unit-cell volume collapse and an electronic band-gap collapse observed by experiments and calculations. Additionally, a band crossing is found to occur in the low-pressure phase near 7 GPa. The pressure dependence of all the Raman-active modes is reported for both phases as well as the pressure dependence of unit-cell parameters and the equations of state. Calculations also provide information on infrared-active phonons and bond distances. These findings provide insights into the effects of pressure on the physical properties of InTaO 4 .

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A combined high-pressure experimental and theoretical study of the electronic band-structure of scheelite-type AWO4 (A = Ca, Sr, Ba, Pb) compounds

Cited by 85 publications

References 42 publications

Study on the Activation of Scheelite and Wolframite by Lead Nitrate

Study on the Activation of Scheelite and Wolframite by Lead Nitrate

New pressure-induced polymorphic transitions of anhydrous magnesium sulfate

Pressure-induced phase transition and band-gap collapse in the wide-band-gap semiconductorInTaO4

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