The high-pressure behavior of a synthetic mordenite- Na (space group: Cmcm or Cmc21) was studied by in situ single-crystal synchrotron X-ray diffraction with a diamond anvil cell up to 9.22(7) GPa. A phase transition, likely displacive in character, occurred between 1.68(7) and 2.70(8) GPa, from a C-centered to a primitive space group: possibly Pbnm, Pbnn or Pbn21. Fitting of the experimental data with III-BM equations of state allowed to describe the elastic behavior of the high-pressure polymorph with a primitive lattice. A very high volume compressibility [KV0 = 25(2) GPa, βV0 = 1/KV0 = 0.040(3) GPa–1; KV′ = (∂KV/∂P)T = 2.0(3)], coupled with a remarkable elastic anisotropy (βb > > βc > βa), was found. Interestingly, the low-P and high-P polymorphs show the same anisotropic compressional scheme. A structure collapse was not observed up to 9.22(7) GPa, even though a strong decrease of the number of observed reflections at the highest pressures suggests an impending amorphization. The structure refinements performed at room-P, 0.98(2) and 1.68(7) GPa allowed to describe, at a first approximation, the mechanisms that govern the framework deformation in the low-P regime: the bulk compression is strongly accommodated by the increase of the ellipticity of the large 12-membered ring channels running along [001].
High-pressure behavior of synthetic mordenite-Na: an in situ single-crystal synchrotron X-ray diffraction study / P. Lotti, G.D. Gatta, M. Merlini, H. Liermann. - In: ZEITSCHRIFT FUR KRISTALLOGRAPHIE. - ISSN 0044-2968. - 230:4(2015), pp. 201-211. [10.1515/zkri-2014-1796]
High-pressure behavior of synthetic mordenite-Na: an in situ single-crystal synchrotron X-ray diffraction study
P. LottiPrimo
;G.D. GattaSecondo
;M. MerliniPenultimo
;
2015
Abstract
The high-pressure behavior of a synthetic mordenite- Na (space group: Cmcm or Cmc21) was studied by in situ single-crystal synchrotron X-ray diffraction with a diamond anvil cell up to 9.22(7) GPa. A phase transition, likely displacive in character, occurred between 1.68(7) and 2.70(8) GPa, from a C-centered to a primitive space group: possibly Pbnm, Pbnn or Pbn21. Fitting of the experimental data with III-BM equations of state allowed to describe the elastic behavior of the high-pressure polymorph with a primitive lattice. A very high volume compressibility [KV0 = 25(2) GPa, βV0 = 1/KV0 = 0.040(3) GPa–1; KV′ = (∂KV/∂P)T = 2.0(3)], coupled with a remarkable elastic anisotropy (βb > > βc > βa), was found. Interestingly, the low-P and high-P polymorphs show the same anisotropic compressional scheme. A structure collapse was not observed up to 9.22(7) GPa, even though a strong decrease of the number of observed reflections at the highest pressures suggests an impending amorphization. The structure refinements performed at room-P, 0.98(2) and 1.68(7) GPa allowed to describe, at a first approximation, the mechanisms that govern the framework deformation in the low-P regime: the bulk compression is strongly accommodated by the increase of the ellipticity of the large 12-membered ring channels running along [001].File | Dimensione | Formato | |
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