Low albite, NaAlSi/sub 3/O/sub 8/: neutron diffraction study of crystal structure at 13 K

Journal Article · · Am. Mineral.; (United States)

OSTI ID:6913790

Smith, J V; Artioli, G; Kvick, A

The crystal structure of low albite, Amelia, Virginia, was determined at 13 K by neutron diffraction (a = 8.1151(8), b = 12.7621(25), c = 7.1576(6) A, ..cap alpha.. = 94.218(12)/sup 0/, ..beta.. = 116.803(8)/sup 0/, ..gamma.. = 87.707(13)/sup 0/; Cl vector). Mean T-O distances are T/sub 1/O 1.743, T/sub 1/m 1.611, T/sub 2/O 1.615, T/sub 2/m 1.616 A. Refinement of scattering lengths yields the following populations: T/sub 1/O 0.997(4) Al; T/sub 1/m 1.001(3) Si; T/sub 2/O 1.002(3) Si; T/sub 2/m 1.006(4) Si; Na 0.972(1) Na. The displacement of the Na atom is represented by an ellipsoid (root-mean-square amplitudes 0.065, 0.073, and 0.108 A) whose shorter axes are constrained by the five near oxygen atoms at 2.361, 2.419, 2.438, 2.500, and 2.614 A. The displacements of all atoms (B/sub iso/: Si 0.19, Al 0.02, O 0.29-0.42, Na 0.56 A/sup 2/) are similar to those for natrolite an scolecite at 20 K and are consistent with qualitative expectations for the zero-point energy. Stereo-chemical interpretation of the T-O distances at low temperature in low albite, natrolite, scolecite, quartz, and cristobalite is incomplete when only first neighbors are considered.

• Research Organization: Univ. of Chicago, IL
• OSTI ID: 6913790
• Journal Information: Am. Mineral.; (United States), Vol. 71:5-6
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ALBITE
CRYSTAL STRUCTURE
ALUMINIUM
CHEMICAL BONDS
NEUTRON DIFFRACTION
SILICON
SODIUM
ULTRALOW TEMPERATURE
ALKALI METALS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
FELDSPARS
METALS
MINERALS
SCATTERING
SEMIMETALS
SILICATE MINERALS
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)