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Crystal Structure And Al/Si Cation Ordering In "Fassaite": A Combined Single Crystal, 27al And 29si Nmr Study, Monika M. Haring
Crystal Structure And Al/Si Cation Ordering In "Fassaite": A Combined Single Crystal, 27al And 29si Nmr Study, Monika M. Haring
Electronic Thesis and Dissertation Repository
Al-,Ti-rich diopside, referred to herein as fassaite, occurs in both terrestrial and extraterrestrial environments. The composition of fassaite, Ca(Mg,Al)(Si,Al)2O6, makes it ideal for Al/Si cation ordering studies. In this study, crystal XRD, 27Al and 29Si MAS NMR as well as 27Al 3QMAS NMR is used to study cation ordering in extraterrestrial fassaite from Allende CAIs and a terrestrial analogue from Fassa Valley Italy. From 27Al and 29Si spectroscopy, fassaite from Allende CAIs is found to have more local Al/Si cation ordering than terrestrial Fassaite. Both terrestrial and extraterrestrial have C2/c …