Application of electron microscopy to sphere-type Al2O3-SiO2 inclusion and platelet-type hematite particles sliced with an ultra-microtome

Transmission electron microscopy was applied to thin samples of fine particles of sphere-type Al2O3-SiO2 inclusion and platelet-type hematite (α-Fe2O3) sliced with an ultra-microtome. The compositions of local areas of the particles were obtained by EDX analysis. An iron sample containing sphere-type inclusions was prepared from 31 mass% CaO-16 mass%SiO2-53 mass%A12O3 slag and Fe-0.96 mass%Si alloy at 1600°C. Also, the hematite containing 2.58 mass % A12O3 was grown in a Na2O·2B2O3 flux. The two types of particles were separated from their matrix components, then fixated with acrylic resin, and finally sliced into thin plates of approx. 50 nm thickness. As a result, the inclusion particles were found to be composed of an Al2O3-SiO2 amorphous phase on the surface region and an A12O3 single crystal phase in the inside region. The hematite particles were determined from their electron diffraction patterns to be single crystals with {0 0 0 l} base planes. It was also confirmed that an A12O3 phase was not deposited on the very outer surface of the hematite particles.