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Commentary on ‘Oldhamite: a new link in upper mantle for C-O-S-Ca cycles and an indicator for planetary habitability’
Full text linkAverage and local structure in P21/c clinopyroxenes along the join diopside-enstatite (CaMgSi2O6-Mg2Si2O6).
No full textThe structure of Pbca orthopyroxenes along the join diopside-enstatite (CaMgSi2O6-Mg2Si2O6).
No full textAuthor Correction: Mg3Al2Si3O12 jeffbenite inclusion in super-deep diamonds is thermodynamically stable at very shallow Earth’s depths (Scientific Reports, (2023), 13, 1, (83), 10.1038/s41598-022-27290-9)
No full textThe Acknowledgments section in the original version of this Article was incomplete. “F.N. thanks the ERC Starting Grant n. 307322.” now reads: “F.N. thanks the ERC Starting Grant n. 307322. D.B. warmly acknowledges financial support by the Italian MIUR PRIN2017 (Project Number 2017KY5ZX8).” The original Article has been corrected
Rietveld refinement of clinopyroxenes with intemediate Ca-content along the join diopside-enstatite
No full textInclusions in diamonds probe Earth’s chemistry through deep time
Full text linkMost of our knowledge about the chemical composition of the Earth's interior is primarily retrieved by indirect observations, experiments and calculations that are limited to simple compositions. Here, the authors present the investigation of inclusions trapped in super deep diamonds as an alternative source of a wealth of information on the chemical state of the Earth's interior through time
HIGH TEMPERATURE BEHAVIOUR OF CLINOPYROXENES ALONG THE JOINS HEDENBERGITE-JADEITE AND JADEITE-ACMITE.
No full textHigh pressure behavior, transformation and crystal structure of synthetic iron-free pigeonite
No full textA single crystal high pressure X-ray investigation was performed up to P=6.5 GPa on a synthetic clinopyroxene of composition Ca0.15(1)Mg1.85(1)Si2.00(1)O6 [Di15En85, unit cell parameters at room pressure: a = 9.6525(6)Å, b = 8.8461(2)Å, c = 5.2036(5)Å, β = 108.370(5)°, V = 421.68(4)Å3].
A first order P21/c-C2/c displacive phase transition was found at P = 5.1 GPa; the transition was revealed by the disappearance of the b reflections (h + k = odd) and by sharp changes in the unit cell parameters. Reversals through the transformation show that, if present, hysteresis is smaller than 0.1 GPa. The volume variation has been described by a third-order Birch-Murnaghan equation of state with V0 = 421.68(8) Å3, KT0 = 102(2) GPa and K′ = 8(1) for the low-symmetry phase (P21/c) and with V0 = 411.06(3) Å3 and KT0 = 108(2) GPa for the high-symmetry phase (C2/c), with K′ fixed to the value obtained for the low-symmetry form. The axial compressibility shows the following scheme: βb > βa ≅ βc > βasinβ for both phases. In comparison with pure clinoenstatite, Di15En85 shows a similar step in unit cell parameters at the transition, the disappearence of hysteresis and a decrease of transition pressure and of bulk modulus.
Full intensity data sets were collected at room pressure, 2.6 and 4.5 GPa for the P21/c phase and at P= 6.2 GPa for the C2/c phase. A slight increase of the intensity of h + k odd reflections and of the difference in the A and B chain kinking angles were observed. A comparison of the structural behavior of the P21/c phase at high temperature and high pressure shows opposite behavior for M2-O bond lengths and O3-O3-O3 kinking angle
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