STUDY OF NON-OXIDE MATERIALS WITH DEFECT STRUCTURES
Abstract
Several ionic fluoride systems, demonstrating the feasibility of preparing materials with controllable defects up to 20 mole %, have been investigated. Methods of preparation are described. The materials were characterized with respect to type of defect present and its influence on the properties of the host structure. A significant new contribution to the literature was the discovery of extensive defect concentration in the tysonite structure and establishment of the defect model as predominantly anion vacancies. Hot-pressed specimens exhibit ionic conduction considerably greater than the non-defect tysonite and other hot-pressed fluorides. A tetragonal phase, heretofore unreported, was found in the system KMgF3-ScF3. Major problems encountered were oxidation and accomplishing homogeneity in the solid solutions. Polycrystalline compacts of these materials were fabricated using hot-pressing apparatus and techniques developed for this purpose. Observed alteration of the refractive index, unit cell size, and density of a material related to a change in type and concentration of defect, and successful compaction of polycrystalline aggregates, demonstrates the feasibility of predicting and tailor-making materials having desired properties.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1964
- Accession Number
- AD0635945
Entities
People
- H. C. Hafner
- P. C. Velasquez