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In situ dehydration of yugawaralite

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Published/Copyright: March 26, 2015
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American Mineralogist
From the journal American Mineralogist Volume 86 Issue 1-2

Abstract

The structural response of the natural zeolite yugawaralite (CaAl2Si6O16·4H2O) upon thermally induced dehydration has been studied by Rietveld analysis of temperature-resolved powder diffraction data collected in situ in the temperature range 315-791 K using synchrotron radiation. The room-temperature monoclinic structure [Pc, a = 6.73200(9), b = 14.0157(2), c = 10.0607(1) Å, β = 111.189(1) °, Z = 2, at 315 K] has the Ca cations in the channels coordinated to four framework O atoms and to four water molecules, with two of the water sites (OW1 and OW4) showing positional disorder progressively disappearing as the dehydration proceeds. The yugawaralite structure reacts to the release of water molecules with small changes in the Ca-O bond distances and minor distortions of the tetrahedral framework up to about 695 K. Above this temperature the Ca coordination falls below 7 (four framework O atoms and three water molecules) and a major rearrangement in the cation coordination takes place, causing a first order phase transition involving both a large decrease in the cell volume and the change in the space group symmetry. A satisfactory structure model for the high-temperature phase stable in the range 695-791 K could not be obtained because of the complexity of the structure. A model approximately describing the average structure [Pn, a = 12.703(1), b = 13.067(1), c = 9.839(1) Å, β = 110.894(9), Z = 4, at 749 K] has been used to follow the temperature evolution of the cell parameters in the measured temperature range. This model involves a sixfold coordination of the Ca cations (five framework O atoms and one water molecule). There is no indication of significant structure changes before collapse, likely occurring when the last water molecule is expelled from the structure and the cation coordination drops below 6, as observed in other Ca-rich zeolites (i.e., laumontite, scolecite, mesolite).

Received: 2000-1-24
Accepted: 2000-8-14
Published Online: 2015-3-26
Published in Print: 2001-1-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Self diffusion of Si and O in dacitic liquid at high pressures
  2. The effect of anhydrous composition on water solubility in granitic melts
  3. Stability and phase relations of Ca[ZnSi3]O8, a new phase with feldspar structure in the system CaO-ZnO-SiO2
  4. Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes: Evidence for a solvus relation between phlogopite and aspidolite
  5. The influence of T, aSiO₂, and fO₂ on exsolution textures in Fe-Mg olivine: An example from augite syenites of the Ilimaussaq Intrusion, South Greenland
  6. An experimental study of the external reduction of olivine single crystals
  7. Determination of site population in olivine: Warnings on X-ray data treatment and refinement
  8. Structural properties of ferromagnesian cordierites
  9. A calorimetric study of zoisite and clinozoisite solid solutions
  10. Mineralogy of lead in a soil developed on a Pb-mineralized sandstone (Largentière, France)
  11. Experimental mixtures of smectite and rectorite: Re-investigation of “fundamental particles” and “interparticle diffraction”
  12. Hydrothermal reactivity of Lu-saturated smectites: Part I. A long-range order study
  13. Hydrothermal reactivity of Lu-saturated smectites: Part II. A short-range order study
  14. Pulsed field gradient proton NMR study of the self-diffusion of H2O in montmorillonite gel: Effects of temperature and water fraction
  15. Structural environment and oxidation state of Mn in goethite-groutite solid-solutions
  16. Structure, compressibility, hydrogen bonding, and dehydration of the tetragonal Mn3+ hydrogarnet, henritermierite
  17. Electric field gradient tensors at the aluminum sites in the Al2SiO5 polymorphs from CCD high-resolution X-ray diffraction data: Comparison with 27Al NMR results
  18. Sodium cation dynamics in nitrate cancrinite: A low and high temperature 23Na and 1H MAS NMR study and high temperature Rietveld structure refinement
  19. O-D…O bond geometry in OD-chondrodite
  20. Refinement of hydrogen positions in synthetic hydroxyl-clinohumite by powder neutron diffraction
  21. In situ dehydration of yugawaralite
  22. Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure—Comment
  23. Reply to Comment on “Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure”
https://doi.org/10.2138/am-2001-0121

Articles in the same Issue

  1. Self diffusion of Si and O in dacitic liquid at high pressures
  2. The effect of anhydrous composition on water solubility in granitic melts
  3. Stability and phase relations of Ca[ZnSi3]O8, a new phase with feldspar structure in the system CaO-ZnO-SiO2
  4. Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes: Evidence for a solvus relation between phlogopite and aspidolite
  5. The influence of T, aSiO₂, and fO₂ on exsolution textures in Fe-Mg olivine: An example from augite syenites of the Ilimaussaq Intrusion, South Greenland
  6. An experimental study of the external reduction of olivine single crystals
  7. Determination of site population in olivine: Warnings on X-ray data treatment and refinement
  8. Structural properties of ferromagnesian cordierites
  9. A calorimetric study of zoisite and clinozoisite solid solutions
  10. Mineralogy of lead in a soil developed on a Pb-mineralized sandstone (Largentière, France)
  11. Experimental mixtures of smectite and rectorite: Re-investigation of “fundamental particles” and “interparticle diffraction”
  12. Hydrothermal reactivity of Lu-saturated smectites: Part I. A long-range order study
  13. Hydrothermal reactivity of Lu-saturated smectites: Part II. A short-range order study
  14. Pulsed field gradient proton NMR study of the self-diffusion of H2O in montmorillonite gel: Effects of temperature and water fraction
  15. Structural environment and oxidation state of Mn in goethite-groutite solid-solutions
  16. Structure, compressibility, hydrogen bonding, and dehydration of the tetragonal Mn3+ hydrogarnet, henritermierite
  17. Electric field gradient tensors at the aluminum sites in the Al2SiO5 polymorphs from CCD high-resolution X-ray diffraction data: Comparison with 27Al NMR results
  18. Sodium cation dynamics in nitrate cancrinite: A low and high temperature 23Na and 1H MAS NMR study and high temperature Rietveld structure refinement
  19. O-D…O bond geometry in OD-chondrodite
  20. Refinement of hydrogen positions in synthetic hydroxyl-clinohumite by powder neutron diffraction
  21. In situ dehydration of yugawaralite
  22. Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure—Comment
  23. Reply to Comment on “Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure”
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