| The compounds BaSe, BaS, BaO, GaSb, GaAs, and GaP were studied under high-pressures using primarily the x-ray diffraction technique. For BaSe, optical reflectivity and electrical resistivity experiments were performed as well.;This thesis also reports on high-pressure energy-dispersive x-ray diffraction (EDXD) experiments which were performed on BaS, BaO, GaSb, GaAs, and GaP. All these experiments were performed at the Cornell High Energy Synchrotron Source (CHESS). The EDXD experiment for BaS revealed a structural transition from the zero-pressure NaCl structure to the CsCl structure at 6.5 GPa. The CsCl structure then remained stable to at least 89.0 GPa, the highest pressure reached in the experiment. For BaO, a structural transition was observed at 10.0 GPa from the NaCl structure to the NiAs structure. This NiAs phase remained stable at 15.0 GPa, at which point it transformed tot he PH;The gallium compounds GaSb, GaAs, and GaP were studied as well. A high-pressure EDXD experiment on GaSb indicated that it transformed according to the following sequence: zinc-blende ;The pressure-induced band overlap metallization of BaSe was studied in this thesis using both high-pressure electrical resistivity and optical reflectivity experiments. The electrical resistivity experiment indicated that the BaSe sample metallized in the region of 52... |
