Defect aggregation kinetics in calcium fluoride

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5875724

Cirillo, K M

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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360602* -- Other Materials-- Structure & Phase Studies
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CALCIUM COMPOUNDS
CALCIUM FLUORIDES
CALCIUM HALIDES
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EUROPIUM IONS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HEAT TREATMENTS
HIGH-TC SUPERCONDUCTORS
ION PAIRS
IONS
LASERS
MATERIALS
MODIFICATIONS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES