Crystal defects and the dissolution kinetics of rutile
- Sandia National, Albuquerque, NM (USA)
The dissolution rate of rutile in hydrofluoric acid was measured to examine the importance of line and point defects on the reaction rate. In spite of this large variation in dislocations and point defect concentrations, the authors observed only a factor of two variation in the reaction rate for shocked and annealed material. Existing theories suggest that etch pits nucleate and grow at the outcrop of a dislocation on the crystal surface. Assuming that the measured dislocation densities can be used to estimate the density of surface outcrops, and that each outcrop dissolves to form an etch pit, the relation between dissolution rates and dislocations can be interpreted in terms of a mean rate of etch pit growth. The mean rate of etch pit growth in shocked samples is less than 9 {times} 10{sup {minus}27} cm{sup 3} s{sup {minus}1}. In experiments with single rutile crystals, however, observable etch pits grow at rates on the order of 1 {times} 10{sup {minus}19} cm{sup 3} s{sup {minus}1}. This discrepancy suggests either that: (i) the observed etch pits grow much more rapidly than the mean rate; of (ii) bulk dislocation density is not a useful measure of potential sites for etch pit growth on rutile crystal surfaces.
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5557569
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:6; ISSN GCACA; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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CAVITIES
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTION KINETICS
CHEMISTRY
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
DISSOLUTION
ELECTRON SPIN RESONANCE
ETCHING
GEOCHEMISTRY
HYDROFLUORIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
KINETICS
MAGNETIC RESONANCE
MATERIALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
REACTION KINETICS
RESONANCE
RUTILE
SURFACE FINISHING
SURFACE PROPERTIES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS