Ende, Martin, Wunder, Bernd, Koch-Müller, Monika, Pippinger, Thoma., Buth, Gernot, Giester, Gerald, Lengauer, Christian L., Libowitzky, Eugen (2016) T-induced displacive phase transition of end-member Pb-lawsonite. Mineralogical Magazine, 80 (2) 249-267 doi:10.1180/minmag.2016.080.015
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | T-induced displacive phase transition of end-member Pb-lawsonite | ||
| Journal | Mineralogical Magazine | ||
| Authors | Ende, Martin | Author | |
| Wunder, Bernd | Author | ||
| Koch-Müller, Monika | Author | ||
| Pippinger, Thoma. | Author | ||
| Buth, Gernot | Author | ||
| Giester, Gerald | Author | ||
| Lengauer, Christian L. | Author | ||
| Libowitzky, Eugen | Author | ||
| Year | 2016 (April) | Volume | 80 |
| Issue | 2 | ||
| Publisher | Mineralogical Society | ||
| DOI | doi:10.1180/minmag.2016.080.015Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 244785 | Long-form Identifier | mindat:1:5:244785:2 |
| GUID | 0 | ||
| Full Reference | Ende, Martin, Wunder, Bernd, Koch-Müller, Monika, Pippinger, Thoma., Buth, Gernot, Giester, Gerald, Lengauer, Christian L., Libowitzky, Eugen (2016) T-induced displacive phase transition of end-member Pb-lawsonite. Mineralogical Magazine, 80 (2) 249-267 doi:10.1180/minmag.2016.080.015 | ||
| Plain Text | Ende, Martin, Wunder, Bernd, Koch-Müller, Monika, Pippinger, Thoma., Buth, Gernot, Giester, Gerald, Lengauer, Christian L., Libowitzky, Eugen (2016) T-induced displacive phase transition of end-member Pb-lawsonite. Mineralogical Magazine, 80 (2) 249-267 doi:10.1180/minmag.2016.080.015 | ||
| Abstract/Notes | AbstractPb-lawsonite, PbAl2[(OH)2|Si2O7]·H2O, space group Pbnm, was synthesized as crystals up to 15 μm × 5 μm × 5 μm in size by a piston cylinder technique at a pressure of ∼4 GPa and a temperature of 873 ± 10 K. Temperature-dependent powder and single-crystal X-ray diffraction (XRD) analyses partly using synchrotron radiation as well as Raman spectroscopic investigations reveal a phase transition around 445 K resulting in the Cmcm high-temperature structure. The transformation temperature is considerably higher than that of lawsonite around 273 K, which is characterized predominantly by proton order/disorder. The transition is confirmed using principal component analysis and subsequent hierarchical cluster analysis on both the powder XRD patterns and the Raman spectra. Furthermore, a non-uniform change is observed around 355 K, which is not as pronounced as the 445 K transition and apparently comes from enhanced hydrogen bonding, which stops the atom shifts in Pb-lawsonite. These are the same bonds that mainly characterize the phase transition in lawsonite around 273 K. In contrast, the structural transition of Pblawsonite at 445 K seems to originate from the interaction of the SiO4 tetrahedra and AlO6 octahedra framework with the Pb2+ cation. The structural environment of Pb2+ can be described by a 12-fold coordination above 445 K, which changes towards irregular ten-fold coordination below this temperature. An assignment of the O–H stretching Raman bands confirms moderately strong H bonds in Pb-lawsonite, whereas both strong and weak H bonds exist in lawsonite. Therefore, a further phase transition of Pblawsonite, similar to that of lawsonite around 273 K, is not expected. | ||
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