A time-of-flight neutron powder diffraction study of MgAl sub 2 O sub 4 at temperatures up to 1,273 K

Journal Article · · American Mineralogist; (United States)

OSTI ID:5732742

Peterson, R C ^[1]; Lager, G A ^[2]; L, Hitterman R ^[3]

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1. Queen's Univ., Kingston, Ontario, (Canada)
2. Univ. of Louisville, KY (United States)
3. Argonne National Lab., Argonne, IL (United States)

Time-of-flight neutron powder diffraction data have been obtained in situ at temperatures up to 1,273 K for two samples of MgAl{sub 2}O{sub 4} (spinel). The samples were synthesized under different experimental conditions (single-crystal boule vs. air-quenched sintered pellet) and exhibited different degrees of cation disorder at room temperature. The Rietveld method was used to fit the data which were obtained initially at room temperature and then at various temperatures as the samples were cooled from 1,273 K. Both samples exhibit statistically equivalent degrees of disorder in the temperature range 973-1,273 K. The atomic fraction of Al in the tetrahedral site increases from 0.25(1) at 973 K to 0.35(2) at 1,273 K. This amount of disorder is significantly less than that determined by an earlier nuclear magnetic resonance experiment. The slight nonuniform variation of the atomic parameters in this temperature range for both samples may suggest a behavior that is inconsistent with a simple process of cation reordering on cooling.

• OSTI ID: 5732742
• Journal Information: American Mineralogist; (United States), Vol. 76:9-10; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
58 GEOSCIENCES
SPINELS
NEUTRON DIFFRACTION
ALUMINATES
CALCULATION METHODS
CATIONS
CHEMICAL PREPARATION
COMPARATIVE EVALUATIONS
COOLING
CRYSTAL STRUCTURE
DISTRIBUTION
MAGNESIUM COMPOUNDS
NUCLEAR MAGNETIC RESONANCE
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CHARGED PARTICLES
COHERENT SCATTERING
DIFFRACTION
EVALUATION
IONS
MAGNETIC RESONANCE
MINERALS
OXIDE MINERALS
OXYGEN COMPOUNDS
RESONANCE
SCATTERING
SYNTHESIS
360602* - Other Materials- Structure & Phase Studies
580000 - Geosciences