Microstructure of electrolytic MnO{sub}2: a transmission electron microscopy study of bulk material

摘要

The microstructure and microcrystallography of bulk electrolytic MnO{sub}2 (EMD) was studied using transmission electron microscopy (TEM); in contrast to previous studies, TEM foils were prepared using ion beam milling, the standard foil preparation technique for ceramics and other brittle materials. Structure is present at two length scales - 11grains," 0.1 to 0.3 μm in diameter, and crystallites, ～10nm in characteristic dimensions. Most grains are multiphase. Comprehensive electron diffraction studies revealed that the overall material contains ～50% Ramsdellite, ～30% ε-MnO{sub}2 and ～15% Pyrolusite. Furthermore, TEM diffraction evidence of ordering in either Ramsdellite or ε-MnO{sub}2 was abundant, and a model for a fully ordered form of ε-MnO{sub}2 is suggested.