Crystal structure and thermal expansion of. cap alpha. -quartz SiO/sub 2/ at low temperatures

Journal Article · Fri Oct 01 04:00:00 EDT 1982 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.330062· OSTI ID:7085850

Lager, G A; Jorgensen, J D; Rotella, F J

The crystal structure of ..cap alpha..-SiO/sub 2/ (low quartz) has been refined at 296, 78, and 13 K from time-of-flight neutron powder diffraction data. The major effect of temperature from 296 to 78 K is a nearly rigid body rotation of the SiO/sub 4/ tetrahedra. Below 78 K, tetrahedral rotation is substantially reduced giving rise to a much smaller thermal expansion. A comparison of the volume dependence of the Si-O-Si angle, the rotation angle for SiO/sub 4/ tetrahedra and the c/a ratio suggests that the mechanism for expansion may be changing from tetrahedral rotation to tetrahedral distortion at the lowest temperatures. The inverse linear relation between the mean Si-O bond distance and -sec(Si-O-Si) which has been observed for silica minerals at both ambient and high-temperature conditions appears to be consistent with the structural variations that occur at low temperatures.

• Research Organization: Department of Geology, University of Louisville, Louisville, Kentucky 40292
• OSTI ID: 7085850
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 53:10; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
BOND ANGLE
BOND LENGTHS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DIMENSIONS
EXPANSION
EXPERIMENTAL DATA
INFORMATION
LATTICE PARAMETERS
LENGTH
LOW TEMPERATURE
MATHEMATICAL MODELS
MEDIUM TEMPERATURE
MINERALS
NEUTRON DIFFRACTION
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POWDERS
QUARTZ
SCATTERING
SILICON COMPOUNDS
SILICON OXIDES
SPACE DEPENDENCE
TEMPERATURE EFFECTS
TETRAGONAL LATTICES
THERMAL EXPANSION
TIME-OF-FLIGHT METHOD
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE