TY  - JOUR
A1  - Grüninger, Helen
A1  - Liu, Zhaodong
A1  - Siegel, Renée
A1  - Boffa Ballaran, Tiziana
A1  - Katsura, Tomoo
A1  - Senker, Jürgen
A1  - Frost, Daniel J.
T1  - Oxygen Vacancy Ordering in Aluminous Bridgmanite in the Earth's Lower Mantle
Y1  - 2019
VL  - 46
IS  - 15
SP  - 8731
EP  - 8740
JF  - Geophysical Research Letters
DO  - 10.1029/2019GL083613
DO  - 10.23689/fidgeo-4734
N2  - Oxygen vacancies (OVs), that charge-balance the replacement of octahedrally coordinated Si4+ by Al3+ in the mineral bridgmanite, will influence transport properties in the lower mantle but little is known about their stability and local structure. Using 27Al nuclear magnetic resonance (NMR) spectroscopy we have characterized OVs within six aluminous bridgmanite samples. In the resulting NMR spectra sixfold, fivefold, and fourfold coordinated Al species are resolved, in addition to near eightfold coordinated Al substituting for Mg. Fivefold coordinated Al is formed by single OV sites but fourfold coordination must result from short range ordering of OVs, producing OV clusters that may form through migration into twin domain walls. Characterizing the occurrence of such OV structures is an important prerequisite for understanding how transport properties change with depth and composition in the lower mantle.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9080
ER  -