Powder neutron diffraction [ISIS Facility (U.K.), POLARIS diffractometer] was used to investigate the effect of elevated pressure on cation partitioning in synthetic Mg0.94Al2.04O4 spinel. The distributions of Mg, Al, and vacancies were studied as a function of pressure, by refinement of the T- and M-site scattering lengths, and determination of the cation partitioning through numerical minimization methods. The partially disordered Mg/Al distribution, which results from the synthesis process, show an increase in ordering between 6 and 18 kbar, where Mg and Al order to the T- and M-sites, respectively. Pressure effectively tends to stabilize MgAl-spinels with a "normal structure," and this behavior is supported by numerical simulations based on classical electrostatic calculations.
In situ powder neutron diffraction of cation partitioning vs. pressure in Mg0.94Al2.04O4 synthetic spinel
ARTIOLI, GILBERTO;
1999
Abstract
Powder neutron diffraction [ISIS Facility (U.K.), POLARIS diffractometer] was used to investigate the effect of elevated pressure on cation partitioning in synthetic Mg0.94Al2.04O4 spinel. The distributions of Mg, Al, and vacancies were studied as a function of pressure, by refinement of the T- and M-site scattering lengths, and determination of the cation partitioning through numerical minimization methods. The partially disordered Mg/Al distribution, which results from the synthesis process, show an increase in ordering between 6 and 18 kbar, where Mg and Al order to the T- and M-sites, respectively. Pressure effectively tends to stabilize MgAl-spinels with a "normal structure," and this behavior is supported by numerical simulations based on classical electrostatic calculations.Pubblicazioni consigliate
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