S. Lauterbach et al., Mossbauer and ELNES spectroscopy of (Mg,Fe)(Si,Al)O-3 perovskite: a highlyoxidised component of the lower mantle, CONTR MIN P, 138(1), 2000, pp. 17-26
(Mg,Fe)(Si,Al)O-3 perovskite samples with varying Fe and Al concentration w
ere synthesised at high pressure and temperature at varying conditions of o
xygen fugacity using a multianvil press, and were characterised using ex si
tu X-ray diffraction, electron microprobe, Mossbauer spectroscopy and analy
tical transmission electron microscopy. The Fe3+/Sigma Fe ratio was determi
ned from Mossbauer spectra recorded at 293 and 80 K, and shows a nearly lin
ear dependence of Fe3+/Sigma Fe with Al composition of (Mg,Fe)(Si,Al)O-3 pe
rovskite. The Fe3+/Sigma Fe values were obtained for selected samples of (M
g,Fe)(Si,Al)O-3 perovskite using electron energy-loss near-edge structure (
ELNES) spectroscopy, and are in excellent agreement with Mossbauer data, de
monstrating that Fe3+/Sigma Fe can be determined with a spatial resolution
on the order of nm. Oxygen concentrations were determined by combining bulk
chemical data with Fe3+/Sigma Fe data determined by Mossbauer spectroscopy
, and show a significant concentration of oxygen vacancies in (Mg,Fe)(Si,Al
)O-3 perovskite.