Physics and Chemistry of Minerals

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Dynamics of the α-β phase transitions in quartz and cristobalite as observed by in-situ high temperature 29Si and 17O NMR
Physics and Chemistry of Minerals - Tập 19 - Trang 307-321 - 1992
Dane R. Spearing, Ian Farnan, Jonathan F. Stebbins
Relaxation times (T1) and lineshapes were examined as a function of temperature through the α-β transition for 29Si in a single crystal of amethyst, and for 29Si and 17O in cristobalite powders. For single crystal quartz, the three 29Si peaks observed at room temperature, representing each of the three differently oriented SiO4 tetrahedra in the unit cell, coalesce with increasing temperature such...... hiện toàn bộ
The stoichiometry of synthetic alunite as a function of hydrothermal aging investigated by solid-state NMR spectroscopy, powder X-ray diffraction and infrared spectroscopy
Physics and Chemistry of Minerals - - 2015
Elisabeth Grube, Ulla Gro Nielsen
Thermodynamic properties of geikielite (MgTiO3) and ilmenite (FeTiO3) derived from vibrational methods combined with Raman and infrared spectroscopic data
Physics and Chemistry of Minerals - Tập 49 - Trang 1-18 - 2022
Michael H. G. Jacobs, Arie P. van den Berg, Rainer Schmid-Fetzer, Jellie de Vries, Wim van Westrenen, Yue Zhao
We present a model for the lattice vibrational density of states of MgTiO3 (geikielite) and FeTiO3 (ilmenite) that predicts thermodynamic properties, in agreement with observational data. The model is based on Kieffer’s method combined with spectroscopic data. For both substances experimental data sets are influenced by non-stoichiometry. For geikielite that affects the volume, whereas for ilmenit...... hiện toàn bộ
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
Co3O4 nanoparticles on the surface of halloysite nanotubes
Physics and Chemistry of Minerals - Tập 39 Số 10 - Trang 789-795 - 2012
Yi Zhang, Huaming Yang
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-pressure phase behavior of MnTiO3: decomposition of perovskite into MnO and MnTi2O5
Physics and Chemistry of Minerals - - 2010
Taku Okada, Takehiko Yagi, Daisuke Nishio-Hamane
The phase relations and compression behavior of MnTiO3 perovskite were examined using a laser-heated diamond-anvil cell, X-ray diffraction, and analytical transmission electron microscopy. The results show that MnTiO3 perovskite becomes unstable and decomposes into MnO and orthorhombic MnTi2O5 phases at above 38 GPa and high temperature. This is the first example of ABO3 perovskite decomposing int...... 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
Surface microtopography of metamorphic white micas
Physics and Chemistry of Minerals - Tập 5 - Trang 65-81 - 1979
Shinji Tomura, Masao Kitamura, Ichiro Sunagawa
Gold decoration and platinum-carbon-shadowing techniques of electron microscopy have been applied to study the surface microtopographs of noncleavage (001) faces of porphyroblastic white micas and sericite crystals collected from the chlorite, biotite, and garnet zones in the Shiragayama area in the Sanbagawa metamorphic terrain, Shikoku, Japan. Two different types of surface microtopograph have b...... hiện toàn bộ
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