Planar defects, electron microscopy

There are two exceptions to the cubic indexing. A low-angle shoulder on the 111 peak has been identified from electron-microscopy studies as a truncation rod arising from planar defects ID. E. Luzzi (private communication)]. The very weak unindexed peak at 0.61 A is attributed to an unknown impurity. 

The extended defect structures that occur in certain non-stoicheiometric compounds have in recent years provided some of the most intriguing problems in solid-state chemistry. The most intensively studied phase showing this class of disorder is Ti02-x> which planar defects known as shear planes have been detected and characterized by electron microscopy. Examples of other simple inorganic compounds containing shear planes are provided by V02 x and The range of... 

Kogure T, Nespolo M (2001) Atomic stractures of planar defects in oxybiotite. Am Mineral 86 336-340 Konishi H, Akai J (1990) HRTEM observation of new complex polytype of biotite from dacites in Higashiyama hills, Niigata, central Japan. Clay Sci 8 25-30 Mauguin MCH (1928) Etude de Micas au moyen du rayons X. Bull Soc fr Mineral Cristallogr 51 285-332 Menter JW (1956) The direct study by electron microscopy of crystal lattices and their imperfections. Proc R Soc London A236 119... 

However, whereas X-ray and neutron diffraction provide only average structures (- Structural Analysis by Diffraction), electron diffraction and microscopy can provide detailed information on local structures, especially when the average structure is known from other techniques. Also planar defects (i.e., local deviations from the average structure) can be studied to suggest possible new. structures in which such defects occur periodically. 

Of these four types, point/linear defects may only be observed at the atomic level, requiring sophisticated electron microscopy. In contrast, planar defects are often visible using a light microscope, and bulk defects are easily observed by the naked eye. 

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