Equation of state of hercynite, FeAl2O4, and high-pressure systematics of Mg-Fe-Cr-Al spinels. (2nd January 2018)

• Record Type: Journal Article
• Authors: Nestola, F.; Periotto, B.; Anzolini, C.; Andreozzi, G. B.; Woodland, A. B.; Lenaz, D.; Alvaro, M.; Princivalle, F.
• Is Part Of: Mineralogical magazine. Volume 79:Number 2(2015:Apr.)
• Page Start: 285
• Page End: 294
• Publication Date: 2018-01-02
• Subjects: hercynite, -- X-ray diffraction, -- high pressure, -- bulk modulus, -- diamond, -- spinel; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/minmag.2015.079.2.07
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: In this work a single crystal of synthetic hercynite, FeAl2 O4, was investigated by X-ray diffraction up to 7.5 GPa and at room temperature, in order to determine its pressure–volume equation of state. The unit-cell volume decreases non-linearly with a reduction of 3.4% (i.e. 18.43 Å 3 ). The pressure–volume data were fitted to a third-order Birch-Murnaghan equation of state providing the following coefficients: V 0 = 542.58(3)Å 3, K T0 = 193.9(1.7) GPa, K ' = 6.0(5). These results are consistent with previous investigations of Cr and Al spinels measured with the same experimental approach but the K T0 differs significantly from the experimental determination carried out more than 40 years ago by Wang and Simmons (1972) by the pulse echo overlap method. Our new results were used to redetermine the FeAl2 O4 (hercynite) = FeO(wüstite) + Al2 O3(corundum) equilibrium in P–T space and obtain geobarometric information for Cr-Al spinels found as inclusions in diamond.