231 research outputs found
High-pressure C2/c - P21/c phase transition along the LiAlSi2O6 - LiGaSi2O6 solid solution
No full textAbstract 3.3
The high-pressure P21/c - C2/c phase transition for the CMS (CaO-MgO-SiO2) clinopyroxenes
No full textJournal of Conference Abstract
The high-pressure C2/c -P21/c phase transition along the LiAlSi2O6 - LiGaSi2O6 solid solution
No full textRoom-temperature equation of state of Li2VOSiO4 up to 8.5 GPa
No full textHigh-pressure single-crystal X-ray diffraction measurements of lattice parameters of the compound Li2VOSiO4, which crystallises with a natisite-type structure, has been carried out to a pressure of 8.54(5) GPa at room temperature. Unit-cell volume data were fitted with a second-order Birch-Murnaghan EoS (BM-EoS), simultaneously refining V0 and K0 using the data weighted by the uncertainties in V. The bulk modulus is K0 = 99(1) GPa, with K′ fixed to 4. Refinements of third order equations-of-state yielded values of K′ that did not differ significantly from 4. The compressibility of the unit-cell is strongly anisotropic with the c axis (K0(c) = 49.7 ± 0.5 GPa) approximately four times more compressible than the a axis (K0(a) = 195 ± 3 GPa). © Springer-Verlag 2007
High 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
Equation of state of the jadeite (NaAlSi2O6) – aegirine (NaFe3+Si2O6) and the jadeite – hedenbergite (CaFe2+Si2O6) solid solutions
No full textAbstract 3.3.b
Elastic properties and high-pressure crystal structure behaviour along the jadeite - hedenbergite solid solution
No full textPremio per il miglior poste
The high-pressure P21/c-C2/c phase transition in Ca0.15Mg1.85Si2O6 clinopyroxene
No full textAbstract 3.2.
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