A high-pressure cubic-to-tetragonal phase-transition in melanophlogite, a SiO2 clathrate phase (Articolo in rivista)

Type
Label
  • A high-pressure cubic-to-tetragonal phase-transition in melanophlogite, a SiO2 clathrate phase (Articolo in rivista) (literal)
Anno
  • 2010-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1016/j.micromeso.2009.10.004 (literal)
Alternative label
  • Tribaudino M., Gatta G.D., Yongjae L. (2010)
    A high-pressure cubic-to-tetragonal phase-transition in melanophlogite, a SiO2 clathrate phase
    in Microporous and mesoporous materials (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Tribaudino M., Gatta G.D., Yongjae L. (literal)
Pagina inizio
  • 267 (literal)
Pagina fine
  • 273 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#altreInformazioni
  • Melanophlogite, Clathrate, High-pressure, Phase-transition, Compressibility (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 129 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Dipartimento di Scienze della Terra, Università di Parma, Parco Area delle Scienze 157/A, 43100 Parma, Italy Dipartimento di Scienze della Terra, Università di Milano, Via Botticelli 23, 20133 Milan, Italy Department of Earth System Sciences, Yonsei University, Seoul 120749, Republic of Korea (literal)
Titolo
  • A high-pressure cubic-to-tetragonal phase-transition in melanophlogite, a SiO2 clathrate phase (literal)
Abstract
  • The crystal-structure and the high-pressure behavior of a natural cubic melanophlogite (Sp. Gr. Pm3n at room-conditions), a type-I SiO2 clathrate containing only methane as guest gas, was investigated by X-ray single-crystal diffraction at room-conditions and in situ high-pressure synchrotron powder diffraction with a diamond anvil cell and methanol:ethanol:water = 16:3:1 (MEW) mixture and silicon-oil (Si-oil) as pressure transmitting media up to about 6 GPa. A cubic-to-tetragonal phase-transition was observed at P P1.14 GPa, in both MEW and Si-oil runs. The tetragonal polymorph is stable up to the highest pressure in the run with MEW, but it switches back to cubic symmetry at P > 3.12 GPa in Si-oil. The different elastic behavior is ascribable to the non-hydrostatic conditions in Si-oil medium at P > 1 GPa. The elastic behavior of melanophlogite was described fitting the P-V data with a Birch-Murnaghan Equation-of-State, showing similar bulk modulus values for the low-pressure cubic and high-pressure tetragonal phases [i.e. K0,L-cub = 23.4(2.4), K0,tetr = 22.2(9)]. The spontaneous strain for the cubic-to-tetragonal transition is almost completely governed by a compression along the c axis, with negligible contribution along a. An inverse behavior is found with respect to the tetragonal-to-cubic high-temperature phase-transition previously described for Mt. Hamilton melanophlogite. A Landau fit of the spontaneous strain (ess), related to the order parameter (Q) of the transition as ess / Q, showed a first-order character of the P-induced phase-transition and a Pc = 1.2(3) GPa. Symmetry breaking spontaneous strain prevails respect to the volume strain, which is however present and significant. (literal)
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