Defects in Oxide Ceramics.
Final rept. 1 Oct 70-30 Sep 71,
UTAH UNIV SALT LAKE CITY DIV OF MATERIALS SCIENCE AND ENGINEERING
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Strontium titanate single crystals were carefully reduced at temperatures ranging from 1200C to 1400C and quenched to room temperature where Hall constants, mass densities, and lattice parameters were measured. The predominant defects at room temperature were found to be doubly ionized oxygen vacancies and conduction band electrons. No evidence was found for singly ionized oxygen vacancies as has been suggested by several authors. Optical absorption within the band gap energy for reduced strontium titanate were attributed to the effect of free carriers with several possible mechanisms Phonon scattering mechanisms seem to predominate at wave lengths from 1.2 microns to 2.2 microns where intravalley or interband transitions may take place. In the wave length region of 0.5 microns to 1.2 microns three peaks at photon energies 1.66, 2.44, and 2.95 eV have been observed which were attributed to interband transitions among the titanium d-like conduction bands. Finally, the existence of p-type SrTiO3 is postulated. Author
- Solid State Physics