HIGH-VOLTAGE HIGH-RESOLUTION ELECTRON-MICROSCOPY ON THIN-FILMS OF MONODISPERSED PSEUDOCUBIC AND PEANUT-TYPE HEMATITE PARTICLES

In order to investigate internal structures of monodispersed hematite (alpha-Fe2O3) particles of pseudocubic and peanut-type shapes prepared by the gel-sol method (J. Colloid Interface Sci., 152 (1992), 587; Colloids Surf. 70 (1992), 167), their thin sections were prepared by an ultra-microtome and studied by transmission electron microscopy. The surfaces and arrangements of the individual small subcrystals as components of the monodispersed particles were clearly observed on the atomic scale by high-voltage high-resolution electron microscopy. This is direct evidence of the polycrystallinity of these particles. Furthermore, it was found that the subcrystals of the pseudocubic particles had a square shape bounded by sharp {01 (1) over bar 2} surfaces lining up with the same orientation, whereas those of the peanut-type particles had relatively round surfaces and the crystallographic orientations of adjacent subcrystals slightly differed from each other.