The Microscopic Basis of the Low-Frequency Excitations in B2O3 Glass (SOLID STATE CHEMISTRY- Amorphous Materials)

We have performed ab initio molecular orbital calculations on the clusters modeling the medium-range ordering (MRO) region of B2O3 glass at the Hartree-Fock (HF)/6-31G* levels. Their equilibrium geometries, harmonic vibrational frequencies, and Raman scattering intensities have been calculated. The calculations have reproduced the boson peak frequencies of vitreous B2O3 observed at 24 cm-1 and 137 cm-1. The normal coordinates have demonstrated that these low-frequency vibrational modes are due to the wavelike motions of atoms within the region composed of one (for the mode at 137 cm-1) or two (for the mode at 24 cm-1) boroxol ring(s). The results suggest that the boson peak originates from the collective harmonic vibrations localized in the MRO region of glasses

Electrical Properties of Transparent Doped Titania Films by Sol-Gel Method (SOLID STATE CHEMISTRY-Amorphous Materials)

Transparent semiconductive TiO2 films co-doped with Ru and Ta (Nb), and Co and Nb (Sb) were prepared on SiO2 glass substrates by the sol-gel method using Ti(OC3H7 i)4 solutions. The solution preparation condition, solution composition, dopant content and heat-treatment temperature all severely affected the electrical resistivity of the resultant films. TiO2 films co-doped with Ru and Ta (Nb) showed n-type conductivity, while those co-doped with Co and Nb (Sb) showed p-type conductivity. It seems that the obtained films can be utilized for assembling all-solid-state TiO2-based pn type solar cell