Biomedical subjects
Publications and source records attributed to Gautam Gundiah.
Germanium oxide (GeO2) nanowires have been prepared by heating a mixture of Ge powder and carbon in an Ar + O2 mixture at 900 degrees C. The nanowires have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and spectroscopic measurements. The nanowires are single crystalline with diameters in the 15-250-nm range. They exhibit characteristic blue luminescence.
High-pressure structural behavior of silicon nanowires is investigated up to approximately 22 GPa using angle dispersive X-ray diffraction measurements. Silicon nanowires transform from the cubic to the beta-tin phase at 7.5-10.5 GPa, to the Imma phase at approximately 14 GPa, and to the primitive hexagonal structure at approximately 16.2 GPa. On complete release of pressure, it transforms to the metastable R8 phase. The observed sequence of phase transitions is the same as that of bulk silicon. Though the X-ray diffraction experiments do not reveal any size effect, the pressure dependence of Raman modes shows that the behavior of nanowires is in between that of the bulk crystal and porous Si.