Alpha-decay event damage in zircon

Journal Article · · American Mineralogist; (United States)

OSTI ID:5732278

Murakami, Takashi ^[1]; Chakoumakos, B C ^[2]; Ewing, R C ^[3]; Lumpkin, G R ^[4]; Weber, W J ^[5]

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1. Japan Atomic Energy Research Inst., Ibaraki-Ken (Japan)
2. Oak Ridge National Lab., TN (United States)
3. Univ. of New Mexico, Albuquerque (United States)
4. Australian Nuclear Science and Technology Organisation, Menai (Australia)
5. Pacific Northwest Lab., Richland, WA (United States)

Based on density measurements, X-ray diffraction analysis, and high-resolution transmission electron microscopy of a suite of natural zircon samples from Sri Lanka, three stages of damage accumulation may be delineated. Stage 1 (< 3 {times} 10{sup 15} {alpha}-decay events/mg) is characterized by sharp Bragg diffraction maxima with a minor contribution from the diffuse-scattering component. Electron diffraction patterns were sharp. Damage is dominated by the accumulation of isolated point defects, which cause unit-cell expansion and distortion that account for most of the decrease in density. These defects may partially anneal over geologic periods of time. Stage 2 (3 {times} 10{sup 15} to 8 {times} 10{sup 15} {alpha}-decay events/mg) is characterized by significant decreases in the intensity of the Bragg diffraction maxima, which becomes asymmetric from increased contributions of the diffuse-scattering component. High-resolution transmission electron microscopy indicated that the microstructure consists of distorted crystalline regions and amorphous tracks caused by {alpha}-recoil nuclei. With increasing {alpha}-decay dose, damaged crystalline regions are converted into aperiodic regions but with no further significant expansion of the unit cell in the remaining crystalline regions. State 3 (> 8 {times} 10{sup 15} {alpha}-decay events/mg) consists of material that is entirely aperiodic as far as can be determined by X-ray or electron diffraction. There was no evidence for the formation of ZrO{sub 2} or SiO{sub 2} as final products during the last stage of metamictization. Based on modeled density changes, aperiodic regions continue to experience a change in structure as they are redamaged.

• DOE Contract Number: FG04-84ER45099; AC05-84OR21400; AC06-76RL01830
• OSTI ID: 5732278
• Journal Information: American Mineralogist; (United States), Journal Name: American Mineralogist; (United States) Vol. 76:9-10; ISSN AMMIA; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360605* -- Materials-- Radiation Effects
58 GEOSCIENCES
580000 -- Geosciences
ACTINIDES
ALPHA DECAY
ANNEALING
ASIA
BRAGG REFLECTION
CHALCOGENIDES
COHERENT SCATTERING
COMPARATIVE EVALUATIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DAMAGE
DECAY
DENSITY
DEVELOPING COUNTRIES
DIFFRACTION
DOPED MATERIALS
DOSES
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
EVALUATION
HEAT TREATMENTS
ISLANDS
MATERIALS
METALS
MICROSCOPY
MICROSTRUCTURE
MINERALS
MORPHOLOGICAL CHANGES
NUCLEAR DECAY
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
PLUTONIUM
POINT DEFECTS
RADIATION DOSES
RADIATION EFFECTS
REFLECTION
SCATTERING
SILICATE MINERALS
SILICON COMPOUNDS
SILICON OXIDES
SRI LANKA
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
TRANSURANIUM ELEMENTS
X-RAY DIFFRACTION
ZIRCON
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES