Defects and mass transport in rutile-structured fluorides. I. Experiment

Journal Article · Tue Aug 15 00:00:00 EDT 1989 · Physical Review (Section) B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.40.3266· OSTI ID:5555258

Ling, S; Nowick, A S ^[1]

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1. Henry Krumb School of Mines, Columbia University, New York, New York 10027 (US)

A study of low-temperature dielectric relaxation of Er{sup 3+}- and Y{sup 3+}-doped MnF{sub 2} crystals in orientations both parallel and perpendicular to the tetragonal {ital c} axis shows the presence of relaxation peaks with very low activation energies {ital E}. Specifically, for both dopants, a prominent peak is found in parallel-oriented samples with {ital E}{similar to}6 meV and in perpendicular orientation with {ital E}=37 meV for Er{sup 3+} and {ital E}=46 meV for Y{sup 3+} doping. Such low {ital E} values are probably too small to be controlled by lattice migration of a defect. With the aid of computer-simulation calculations, these peaks were interpreted as resulting from a stable low-symmetry configuration of a dopant-F{sub {ital i}} pair (F{sub {ital i}} is the fluorine-ion interstitial), which allows dipole reorientation by motions involving small fractions of lattice distances. It is then concluded that the intrinsic defect in this crystal is of the anion Frenkel, and not the Schottky, type, as had been proposed earlier. Electrical-conductivity measurements on pure and doped MnF{sub 2} were then interpreted in terms of this defect model to obtain {ital H}{sub {ital f}}=3.56{plus minus}0.02 eV for the formation enthalpy of the anion Frenkel defect, {ital H}{sub {ital m}}=0.10 eV for the migration enthalpy of the F{sub {ital i}}, and {ital H}{sub {ital A}}=1.1 eV for the dopant-F{sub {ital i}} association enthalpy. The results agree well with the computer-simulation calculations given in the following paper.

• OSTI ID: 5555258
• Journal Information: Physical Review (Section) B: Condensed Matter; (USA), Vol. 40:5; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
MANGANESE FLUORIDES
DIELECTRIC PROPERTIES
ELECTRIC CONDUCTIVITY
ERBIUM ADDITIONS
FRENKEL DEFECTS
IONS
RELAXATION LOSSES
YTTRIUM ADDITIONS
ALLOYS
CHARGED PARTICLES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRICAL PROPERTIES
ENERGY LOSSES
ERBIUM ALLOYS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
LOSSES
MANGANESE COMPOUNDS
MANGANESE HALIDES
PHYSICAL PROPERTIES
POINT DEFECTS
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
TRANSITION ELEMENT COMPOUNDS
VACANCIES
YTTRIUM ALLOYS
360603* - Materials- Properties