Physics and Chemistry of Minerals

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Visualization-based analysis of structural and dynamical properties of simulated hydrous silicate melt
Physics and Chemistry of Minerals - Tập 37 - Trang 103-117 - 2009
Bijaya B. Karki, Dipesh Bhattarai, Mainak Mookherjee, Lars Stixrude
We have explored first-principles molecular dynamics simulation data for hydrous MgSiO3 liquid (with 10 wt% water) to gain insight into its structural and dynamical behavior as a function of pressure (0–150 GPa) and temperature (2,000–6,000 K). By visualizing/analyzing a number of parameters associated with short- and mid-range orders, we have shown that the melt structure changes substantially on...... hiện toàn bộ
Biradical states of oxygen-vacancy defects in α-quartz: centers $$ E_{2}^{\prime \prime } $$ and $$ E_{4}^{\prime \prime } $$
Physics and Chemistry of Minerals - Tập 38 - Trang 647-654 - 2011
Rudolf I. Mashkovtsev, Yuanming Pan
Several new radiation defects with total electron spin S = 1 occurring in electron-irradiated, synthetic α-quartz have been observed by using electron paramagnetic resonance spectroscopy. These defects are considered to be biradicals, i.e., pairs of S = 1/2 species. The concentration of these centers depends on the condition of the fast-electron irradiation. They have different decay behaviors tha...... hiện toàn bộ
High-temperature thermal expansion of lime, periclase, corundum and spinel
Physics and Chemistry of Minerals - Tập 27 - Trang 103-111 - 1999
G. Fiquet, P. Richet, G. Montagnac
The high-temperature cell parameters of lime (CaO), periclase (MgO), corundum (Al2O3), and spinel (MgAl2O4) have been determined from 300 up to 3000 K through X-ray diffraction experiments with synchrotron radiation. The good agreement found with dilatometric results suggests that vacancy-type defects do not make a large contribution to thermal expansion for these oxides, even near the melting po...... hiện toàn bộ
Crystal structure and investigation of Bi2TeO6·nH2O (0 ≤ n ≤ $${\raise0.5ex\hbox{$\scriptstyle 2$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 3$}}$$ ): natural and synthetic montanite
Physics and Chemistry of Minerals - Tập 49 - Trang 1-16 - 2022
Owen P. Missen, Stuart J. Mills, Michael S. Rumsey, Matthias Weil, Werner Artner, John Spratt, Jens Najorka
The crystal structure of montanite has been determined using single-crystal X-ray diffraction on a synthetic sample, supported by powder X-ray diffraction (PXRD), electron microprobe analysis (EPMA) and thermogravimetric analyses (TGA). Montanite was first described in 1868 as Bi2TeO6·nH2O (n = 1 or 2). The determination of the crystal structure of synthetic montanite (refined composition Bi2TeO6·...... hiện toàn bộ
First-principles-based calculations of the CaCO3–MgCO3 and CdCO3–MgCO3 subsolidus phase diagrams
Physics and Chemistry of Minerals - Tập 30 - Trang 88-97 - 2003
B. P. Burton, A. Van de Walle
Planewave pseudopotential calculations of supercell total energies were used as bases for first-principles calculations of the CaCO3–MgCO3 and CdCO3–MgCO3 phase diagrams. Calculated phase diagrams are in qualitative to semiquantitative agreement with experiment. Two unobserved phases, Cd3Mg (CO3)4 and CdMg3(CO3)4, are predicted. No new phases are predicted in the CaCO3–MgCO3 system, but a low-lyi...... hiện toàn bộ
Mössbauer investigation of niningerite solid solutions (Mg,Fe)S
Physics and Chemistry of Minerals - Tập 10 - Trang 245-249 - 1984
Margery D. Osborne, Michael E. Fleet
57Fe Mössbauer spectra of (Mg,Fe)S solid solutions (niningerite) quenched from 1,000° C exhibit a singlet only within the composition range 8.4 to 50.0 mol. percent FeS. The isomer shift decreases progressively with increasing FeS content (from 0.99 to 0.95 mm/s) and extrapolates to a value of about 0.9 mm/s for FeS (halite structure), in close agreement with the isomer shift for FeS (troilite). ...... hiện toàn bộ
Generation of hydrogen ions and hydrogen gas in quartz?water crushing experiments: an example of chemical processes in active faults
Physics and Chemistry of Minerals - Tập 31 Số 3 - Trang 176-182 - 2004
Kazuko Saruwatari, J. Kameda, Hisashi Tanaka
Melilite-type and melilite-related compounds: structural variations along the join Sr2−x Ba x MgSi2O7 (0 ≤ x ≤ 2) and high-pressure behavior of the two end-members
Physics and Chemistry of Minerals - Tập 39 - Trang 199-211 - 2011
Matteo Ardit, Michele Dondi, Marco Merlini, Giuseppe Cruciani
The structural variations along the solid solution Sr2−x Ba x MgSi2O7 (0 ≤ x ≤ 2), combined to the high-pressure characterization of the two end-members, have been studied. A topological change from the tetragonal (melilite-type) to the monoclinic (melilite-related) structure along the join Sr2MgSi2O7 (e.g., ...... hiện toàn bộ
Atomistic simulation of the structure and elastic properties of pyrite (FeS2) as a function of pressure
Physics and Chemistry of Minerals - Tập 30 - Trang 615-619 - 2003
H.M. Sithole, P.E. Ngoepe, K. Wright
Interatomic potential parameters have been derived at simulated temperatures of 0 K and 300 K to model pyrite FeS2. The predicted pyrite structures are within 1% of those determined experimentally, while the calculated bulk modulus is within 7%. The model is also able to simulate the properties of marcasite, even though no data for this phase were included in the fitting procedure. There is almost...... hiện toàn bộ
Lattice dynamics of andalusite: Prediction and experiment
Physics and Chemistry of Minerals - Tập 17 - Trang 453-461 - 1990
B. Winkler, W. Buehrer
Static energy minimization calculations have been used to obtain a relaxed structure of andalusite using a core-shell model with a set of transferable potential parameters. Subsequent lattice dynamics calculations have been used to calculate the eigenvalues and the eigenvectors of the dynamical matrix. The results of these calculations are compared with experimental data obtained by inelastic neut...... hiện toàn bộ
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