Defect aggregation kinetics in calcium fluoride
Defects in solid materials are responsible for many of their most interesting and critical properties. The authors have developed a site-selective laser technique that allows us to monitor the aggregation of rare earth ion defects in solids on the microscopic scale. This excitation absorption laser method enables us to derive kinetic rate information and thermodynamic parameters for the distribution of defects in solids. For doped materials, various types of defects arise when the dopant ions have ionic charges that differ from the charges of host crystal ions. In model systems such as alkaline earth fluorides doped with trivalent rare earth ions, some defect sites consist of a single dopant ion, while others consist of clusters of dopant cations and interstitial anions. Heat treatment of doped samples leads to a distribution of the various types of defect sites that is characteristic of the temperature and length of heat treatment and the total dopant ion concentration. The results from a study of the formation of trivalent europium ion defect aggregates in calcium fluoride indicate that our method successfully monitors changes in individual site concentrations resulting from heat treatment. The results of this study are consistent with the formation of negatively charged dimer and trimer defects in Eu{sup 3+}:CaF{sub 2} crystals from isolated europium ion and (Eu:F{sub i}) single pair defects. In addition, he presents evidence for rapid equilibrium between the isolated ion and the single pair. Other work presented in this thesis includes the development of a high-temperature fluorine oxidation apparatus that was used to convert divalent europium ions to the trivalent state in calcium fluoride single crystals. This apparatus was also used to increase the superconducting {Tc}'s of YBa{sub 2}Cu{sub 3}O{sub 7-x} through modification of copper-oxygen oxidation states.
- Research Organization:
- Wisconsin Univ., Madison, WI (USA)
- OSTI ID:
- 5875724
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Defect processes involving oxygen-compensated sites in CaF/sub 2/ precipitates doped with lanthanides and actinides
Photon up-conversion production in Tb{sup 3+}–Yb{sup 3+} co-doped CaF{sub 2} phosphors prepared by combustion synthesis
Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
SUPERCONDUCTIVITY
CALCIUM FLUORIDES
CRYSTAL DEFECTS
COPPER OXIDES
YTTRIUM OXIDES
DOPED MATERIALS
EUROPIUM IONS
HEAT TREATMENTS
HIGH-TC SUPERCONDUCTORS
ION PAIRS
IONS
LASERS
MATERIALS
MODIFICATIONS
OXIDATION
TRANSITION TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM HALIDES
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
COPPER COMPOUNDS
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360602* - Other Materials- Structure & Phase Studies
360204 - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity