Orientational disorder in Na/sub 3/PSO/sub 3/. 12H/sub 2/O x-ray diffraction and computer simulation studies

Book · Fri Jan 01 00:00:00 EST 1982

OSTI ID:7007806

Goldstein, B M

Na/sub 3/PSO/sub 3/.12H/sub 2/O crystallizes in the trigonal space group R3c with a = 9.061(2), c = 34.34(2) A (hexagonal axes), Z = 6, V = 2441.6 A/sup 2/, D/sub c/ = 1/612 MgM/sup -3/, ..mu.. (Mo k/sup -/2chemically bond) = 0.45 mm/sup -1/, F(000) = 1248. Final R = 0.051 for 326 independent observed reflections. The structure consists of discrete (PSO/sub 3/)/sup 3 -/ anions and (Na/sub 3/)/sup 3 +/(H/sub 2/O)/sub 12/ groups. All Na, P, and S atoms lie on the unique axis. Hydrogen bonds involving all water molecules link the cation complexes both directly and through water-anion interactions. The (PSO/sub 3/)/sup 3 -/ anions are disordered with equal occupancy over two orientations related by the point symmetry 32. A model has been developed to simulate this type of disorder. It assumes that the occupation of alternative anion orientations occurs during crystal growth. This process is simulated by the sequential addition of Na/sub 3/PSO/sub 3/.12H/sub 2/O units to randomly selected nearest neighbor lattice sites. Each unit either binds to the lattice in one of four configurations or does not bind. The probability of occupation of each of these states is given by a canonical distribution. The choice of state is determined by comparison of the distribution to a random number. The energy of the unit in each bound state is calculated using electrostatic, induction, hydrogen bond, dispersion and repulsion interactions. The energy of the nonbound state is a model parameter. Once a unit binds to the lattice, it cannot change its parameter. Once a unit binds to the lattice, it cannot change its configuration, reflecting the non-cooperative nature of a static disorder.

• OSTI ID: 7007806
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
62 RADIOLOGY AND NUCLEAR MEDICINE
ORDER-DISORDER TRANSFORMATIONS
MATHEMATICAL MODELS
PHOSPHORUS COMPLEXES
CRYSTAL STRUCTURE
SODIUM COMPOUNDS
SULFITES
CHEMICAL BONDS
CRYSTAL-PHASE TRANSFORMATIONS
EXPERIMENTAL DATA
HYDROGEN
LATTICE PARAMETERS
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
COHERENT SCATTERING
COMPLEXES
DATA
DIFFRACTION
ELEMENTS
INFORMATION
NONMETALS
NUMERICAL DATA
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
SCATTERING
SULFUR COMPOUNDS
360602* - Other Materials- Structure & Phase Studies
550600 - Medicine