SYMMETRICAL LASER CRYSTALS
Abstract
The development of cubic perovskites as symmetric hosts for laser dopant ions is of interest because long fluorescent lifetimes are to be expected. Other work on LaAlO3:Cr appears to confirm this. The simple II-IV perovskites are of interest as hosts for divalent and tetravalent dopants, but only four such compounds SrTiO3, SrSnO3, BaSnO3 and BaZrO3 are known to be cubic at room temperature. The low dielectric properties and stability toward reduction of BaZrO3 makes it the most attractive potential host. The refractory nature of this compound has heretofore prohibited melt synthesis of single crystal BaZrO3. A novel crucible-less melting technique, referred to as 'skull- melting', was studied intensively as a means for producing single crystals of BaZrO3 (and SrTiO3). The process involves inductive coupling of electromagnetic radiation directly to the melt which acts as its own susceptor. The effects of many of the numerous variables, both thermal and electrical, on the process were studied. The coupling of energy is found to depend primarily on the frequency and the size and electrical conductivity of the melt. Numerous experiments demonstrated that SrTiO3 (and BaTiO3) may be fused by this process in a nearly reproducible manner and maintained in the molten state apparently indefinitely. Many attempts were made to pull single crystals of SrTiO3 (and BaTiO3) but only dark, polycrystalline masses of partially deoxidized material were obtained.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 30, 1965
- Accession Number
- AD0624514
Entities
People
- O. H. Nestor