Home A new rare earth disilicate (REE2Si2O7; REE = Dy, Tm, Lu; type-L): Evidence for nonquenchable 10 GPa polymorph with silicon in fivefold trigonal bipyramidal coordination?
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A new rare earth disilicate (REE2Si2O7; REE = Dy, Tm, Lu; type-L): Evidence for nonquenchable 10 GPa polymorph with silicon in fivefold trigonal bipyramidal coordination?

  • Michael E. Fleet EMAIL logo and Xiaoyang Liu
Published/Copyright: March 28, 2015
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American Mineralogist
From the journal American Mineralogist Volume 89 Issue 2-3

Abstract

A new structure type (L) is reported for disilicates of the middle and heavy rare earth elements (REE) quenched from 10 GPa, 1600-1700 °C. Crystal data are: triclinic, space group P1̅ , Z = 6; Dy2Si2O7: a = 6.5971(3), b = 6.6504(2), c = 18.0582(6) Å, α = 83.791(2), β = 88.653(2), γ = 88.498(2)°, V = 787.2 Å3, and Dx = 6.242 g/cm3; Tm2Si2O7: a = 6.5499(2), b = 6.5876(2), c = 17.8916(7) Å, α = 83.828(1), β = 88.368(1), γ = 88.152(2)°, V = 766.9 Å3, and Dx = 6.574 g/cm3; Lu2Si2O7: a = 6.5240(2), b = 6.5553(2), c = 17.7909(6) Å, α = 83.977(2), β = 88.074(2), γ = 87.846(2)°, V = 755.8 Å3, and Dx = 6.830 g/cm3. The type-L structure comprises linear trisilicate [Si3O10]8- and orthosilicate [SiO4]4- ions cross linked by REE3+ in one sevenfold and five eightfold coordinated positions (to 3.0 Å), and is assembled from alternating (001) strips of the type-B structure of REE2Si2O7 and a sheared structure containing structural elements found in the type-B structure but with Si distributed with 50% occupancy over two face-sharing tetrahedra. The geometry of these half-occupied tetrahedra is consistent with decomposition of a SiO5 trigonal bipyramid during quenching of the pressure.

Received: 2003-3-27
Accepted: 2003-9-17
Published Online: 2015-3-28
Published in Print: 2004-2-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Composition and I4/m-P42/n phase transition in scapolite solid solutions
  2. Synthesis and characterization of K2Ca5(SO4)6·H2O, the equivalent of görgeyite, a rare evaporite mineral
  3. Phase relations in the system Fe-FeSi at 21 GPa
  4. The speciation of dissolved H2O in dacitic melt
  5. Nucleation and growth kinetics of the α-β transformation in Mg2SiO4determined by in situ synchrotron powder X-ray diffraction
  6. Experimental determination of siderite stability and application to Martian Meteorite ALH84001
  7. Determination of the molar absorption coefficient for the infrared absorption band of CO2in rhyolitic glasses
  8. Crystallographic properties of the calcium phosphate mineral, brushite, by means of First Principles calculations
  9. The crystal structure of jonesite, Ba2(K,Na)[Ti2(Si5Al)O18(H2O)](H2O)n: A first example of titanosilicate with porous double layers
  10. Crystal-chemistry of talc: A near infrared (NIR) spectroscopy study
  11. Synthesis of beryllian sapphirine in the system MgO-BeO-Al2O3-SiO2-H2O and comparison with naturally occurring beryllian sapphirine and khmaralite, Part 2: A chemographic study of Be content as a function of P, T, assemblage and FeMg–1exchange
  12. Spriggite, Pb3[(UO2)6O8(OH)2](H2O)3, a new mineral with β-U3O8–type sheets: Description and crystal structure
  13. Sieve-textured plagioclase in dacitic magma: Interference imaging results
  14. Single crystal raman spectroscopy of cerussite
  15. Sodalite: High-temperature structures obtained from synchrotron radiation and Rietveld refinements
  16. The structure of metahohmannite, Fe3+2[O(SO4)2]⋅4H2O, by in situ synchrotron powder diffraction
  17. High-pressure synchrotron X-ray diffraction study of spessartine and uvarovite: A comparison between different equation of state models
  18. Quantum calculations of the electronic structure and NMR quadrupolar interaction parameters for tugtupite
  19. Identification of pyrite valence band contributions using synchrotron-excited X-ray photoelectron spectroscopy
  20. Micro-Raman studies of gypsum in the temperature range between 9 K and 373 K
  21. A new rare earth disilicate (REE2Si2O7; REE = Dy, Tm, Lu; type-L): Evidence for nonquenchable 10 GPa polymorph with silicon in fivefold trigonal bipyramidal coordination?
  22. Structural variations in the brownmillerite series Ca2(Fe2–xAlx)O5: Single-crystal X-ray diffraction at 25 °C and high-temperature X-ray powder diffraction (25 °C ≤ T ≤ 1000 °C)
  23. Peculiarity and defect structure of the natural and synthetic zeolite mordenite: A single-crystal X-ray study
  24. Model independent phase equilibrium constraints on the ferrosilite activity in the binary Fe-Mg orthopyroxene solid solution
  25. Microstructural study of synthetic sintered diamond and comparison with carbonado, a natural polycrystalline diamond
  26. Structural and chemical response to varying [4]B content in zoned Fe-bearing olenite from Koralpe, Austria
  27. A new dense silica polymorph: A possible link between tetrahedrally and octahedrally coordinated silica
  28. Epitaxial relationships of clinopyroxene-hosted magnetite determined using electron backscatter diffraction (EBSD) technique
https://doi.org/10.2138/am-2004-2-321

Articles in the same Issue

  1. Composition and I4/m-P42/n phase transition in scapolite solid solutions
  2. Synthesis and characterization of K2Ca5(SO4)6·H2O, the equivalent of görgeyite, a rare evaporite mineral
  3. Phase relations in the system Fe-FeSi at 21 GPa
  4. The speciation of dissolved H2O in dacitic melt
  5. Nucleation and growth kinetics of the α-β transformation in Mg2SiO4determined by in situ synchrotron powder X-ray diffraction
  6. Experimental determination of siderite stability and application to Martian Meteorite ALH84001
  7. Determination of the molar absorption coefficient for the infrared absorption band of CO2in rhyolitic glasses
  8. Crystallographic properties of the calcium phosphate mineral, brushite, by means of First Principles calculations
  9. The crystal structure of jonesite, Ba2(K,Na)[Ti2(Si5Al)O18(H2O)](H2O)n: A first example of titanosilicate with porous double layers
  10. Crystal-chemistry of talc: A near infrared (NIR) spectroscopy study
  11. Synthesis of beryllian sapphirine in the system MgO-BeO-Al2O3-SiO2-H2O and comparison with naturally occurring beryllian sapphirine and khmaralite, Part 2: A chemographic study of Be content as a function of P, T, assemblage and FeMg–1exchange
  12. Spriggite, Pb3[(UO2)6O8(OH)2](H2O)3, a new mineral with β-U3O8–type sheets: Description and crystal structure
  13. Sieve-textured plagioclase in dacitic magma: Interference imaging results
  14. Single crystal raman spectroscopy of cerussite
  15. Sodalite: High-temperature structures obtained from synchrotron radiation and Rietveld refinements
  16. The structure of metahohmannite, Fe3+2[O(SO4)2]⋅4H2O, by in situ synchrotron powder diffraction
  17. High-pressure synchrotron X-ray diffraction study of spessartine and uvarovite: A comparison between different equation of state models
  18. Quantum calculations of the electronic structure and NMR quadrupolar interaction parameters for tugtupite
  19. Identification of pyrite valence band contributions using synchrotron-excited X-ray photoelectron spectroscopy
  20. Micro-Raman studies of gypsum in the temperature range between 9 K and 373 K
  21. A new rare earth disilicate (REE2Si2O7; REE = Dy, Tm, Lu; type-L): Evidence for nonquenchable 10 GPa polymorph with silicon in fivefold trigonal bipyramidal coordination?
  22. Structural variations in the brownmillerite series Ca2(Fe2–xAlx)O5: Single-crystal X-ray diffraction at 25 °C and high-temperature X-ray powder diffraction (25 °C ≤ T ≤ 1000 °C)
  23. Peculiarity and defect structure of the natural and synthetic zeolite mordenite: A single-crystal X-ray study
  24. Model independent phase equilibrium constraints on the ferrosilite activity in the binary Fe-Mg orthopyroxene solid solution
  25. Microstructural study of synthetic sintered diamond and comparison with carbonado, a natural polycrystalline diamond
  26. Structural and chemical response to varying [4]B content in zoned Fe-bearing olenite from Koralpe, Austria
  27. A new dense silica polymorph: A possible link between tetrahedrally and octahedrally coordinated silica
  28. Epitaxial relationships of clinopyroxene-hosted magnetite determined using electron backscatter diffraction (EBSD) technique
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