Cation partitioning versus temperature in Mg0.70Fe0.23Al1.97O4 synthetic spinels, by in situ neutron powder diffraction
Articolo
Data di Pubblicazione:
1999
Citazione:
Cation partitioning versus temperature in Mg0.70Fe0.23Al1.97O4 synthetic spinels, by in situ neutron powder diffraction / A. Pavese, G. Artioli, U. Russo, A. Hoser A.. - In: PHYSICS AND CHEMISTRY OF MINERALS. - ISSN 0342-1791. - 26:3(1999 Feb), pp. 242-250. [10.1007/s002690050183]
Abstract:
Neutron powder diffraction experiments in the temperature range 300-1770 K were performed at BENSC, Berlin, Germany, on synthetic (Mg0.70Fe0.23) Al1.97O4. The cation partitioning over the crystallographic tetrahedral and octahedral sites was determined as a function of temperature through joint Rietveld refinements and advanced minimization techniques. The thermal expansion coefficients of the lattice parameter and inter-atomic bond lengths were also obtained from the full-profile structure refinements. The behaviour of the polyhedral bond-lengths, especially the T-O distances, and of the cell constant upon heating, clearly indicate that the interdiffusion of tetrahedral and octahedral Mg/Al cations starts at about 950 K. This result is straightforwardly supported by the direct analysis of the neutron site scattering factors: Fe always retains tetrahedral coordination at all temperatures, and the cation rearrangement is entirely due to Mg and Al diffusion.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Neutron powder diffraction; Ordering versus T; Synthetic spinels
Elenco autori:
A. Pavese, G. Artioli, U. Russo, A. Hoser A.
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