Synthetic norsethite, BaMg(CO<sub>3</sub>)<sub>2</sub>
- Autor(en)
- Herta Silvia Effenberger, Thomas Pippinger, Eugen Libowitzky, Christian Lengauer, Ronald Miletich-Pawliczek
- Abstrakt
The crystal sbuctme of synthetic Ba!'t'fg(C03)2 whose mineral name is norsctbite was re-investigatedby single-crystal X-my diffraction. Complementary it~ situ high- and low-·tcmpcr.rmre s~udies by meansof vibrational spccbOscopy (R.ama~ lR). powder X-rny dif&action ·techniques and thennal analyseswere performed. Diffraction images (298 .K; P ila~us pixel detector) revealed weak supcrsuuctmereflections caused by the displacement of the 0 atoms in the earlier considered R3m structure model(a = 5.0212(9). Cnew = 2 Culd = 33.58 1(6) ~ RJc, Z = 6, .R1 = 0.011, sinomega/lambda. =< 0.99' A1 1). Thennalanalyses reveal dccarbonatization in two decomposition steps above 750 K. and the heat-Dow CUJ"ves(difference scanning calorimcrry) give clear evidence of a weak and rever.sible endothennal change at343± 1 K. This agrees with a discon·tinui'ty in the lR and single-crystal Raman spectra. The changingtrend of the cia ratio supports this discon·tinuity indicating a tcmpcra~me-induced struch.tr.il transitionin the range between 343 and 313 K. As the change of ·the unit-cell volmne is almost linear, ·thecharacter of the transition is apparently second order and matches tbc mechanism of a subtledisplacement of the oxygen atom position. The apparent instability of ·the R3c suuctme is alsoevidenced by the remarkably larger aniso·uopic displacement of tbc oxygen atom.
- Organisation(en)
- Institut für Mineralogie und Kristallographie
- Journal
- Mineralogical Magazine
- Band
- 78
- Seiten
- 1589-1611
- Anzahl der Seiten
- 23
- ISSN
- 0026-461X
- DOI
- https://doi.org/10.1180/minmag.2014.078.7.05
- Publikationsdatum
- 12-2014
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105116 Mineralogie, 104017 Physikalische Chemie, 104011 Materialchemie, 105113 Kristallographie
- Schlagwörter
- ASJC Scopus Sachgebiete
- Geochemistry and Petrology
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/synthetic-norsethite-bamgco32(c3b20626-7d23-4e27-a66f-5fb021746a94).html