LARGE-ANGLE CONVERGENT-BEAM ELECTRON-DIFFRACTION DETERMINATIONS OF DISLOCATION BURGERS VECTORS IN SYNTHETIC STISHOVITE

Polycrystalline stishovite, synthesized in a multi-anvil apparatus at 15 GPa and 1200 degrees C, contains numerous dislocations. The microst ructures of the recovered material have been investigated using Transm ission Electron Microscopy (TEM). The Burgers vectors of the dislocati ons were determined using Large Angle Convergent Beam Electron Diffrac tion (LACBED), We find that < 100 >, < 001 >, < 110 > and < 101 > disl ocations were activated in the stishovite during the synthesis experim ents. Dislocation microstructures, indicative of dislocation glide, su ggest that plastic deformation occurred during quench. Subgrain bounda ries that are present in some grains indicate that some recovery occur red. As recovery is unlikely during quench, deformation also occurred during synthesis.