Photorefractive Effect in Barium Titanate Crystals
Abstract
Variable-valent iron impurities have been suggested as the source of photorefractive charge carriers in BaTiO3. Very high-purity BaTiO3 crystals were grown with transition-metal impurity levels below the 10 to the 16th power/cc baseline estimate for photorefractivity. Iron-doped crystals also were grown with concentrations of 5, 50, 250, 500, 750, and 1000 ppm Fe. A study of some growth problems effecting purity and perfection of TSSG BaTiO3 crystals was performed. Some preliminary growth experiments in an rf heated Czochralski furnace indicated that it might be possible to utilize the cleaner growth environment of this type of equipment for BaTiO3. Studies were also conducted to investigate the problem of capping after seeding in the TSSG process. It was concluded that convective instabilities in the melt were probably the limiting factor. Keywords: Chemical purification; Crystal growth; Photorefractive effect; Iron doped; Barium titanate.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 1988
- Accession Number
- ADA201406
Entities
People
- A. Linz
- H. P. Jenssen
Organizations
- Massachusetts Institute of Technology