VALENCE STATE MAPPING AND QUANTITATIVE ELECTRON SPECTROSCOPIC IMAGING OF EXSOLUTION IN TITANOHEMATITE BY ENERGY-FILTERED TEM

Abstract

The microstructure of hematite-ilmenite exsolution intergrowth of a natural titanohematite crystal from a granulite has been investigated in a transmission electron microscope equipped with an energy filter. Special emphasis is on quantitative compositional mapping at the nanometre scale using electron spectroscopic imaging, as well as mapping the Fe3+d Fe2+lence distribution in the intergrowth. Quantitative point analyses by energy-dispersive X-ray analysis have been compared with results from electron energy-loss spectroscopy and element-distribution mapping. The results indicate that the coexisting compositions of the two phases (Ilm8812d Ilm1684re independent of the size of the exsolution. The application of quantitative mapping to determining diffusion profiles around precipitates is demonstrated.