The distribution of transition metal cations in spinels

doi:10.1016/0022-3697(57)90034-3

Journal of Physics and Chemistry of Solids

Volume 3, Issues 3–4, 1957, Pages 311-317

https://doi.org/10.1016/0022-3697(57)90034-3 Get rights and content

Abstract

Crystal field theory in conjunction with spectroscopic data may be applied to give quantitatively the d-shell splitting and the resulting stabilization of a transition metal ion in a crystal site of given symmetry. The thermodynamic stabilization values are found for both octahedral and tetrahedral sites in the spinel lattice. The differences between these values is the site preference energy. The cation distributions predicted from this energy are in good agreement with known experimental data. The occurrence of a large Jahn-Teller effect is correlated with tetragonal phase formation.

References (19)

J.H. Van Vleck
J. Chem. Phy.
(1939)
E.W. Gorter
Philips Res. Rep.
(1954)
Greenwald et al.
J. Chem. Phys.
(1954)
F.C. Romeijn
Philips Res. Rep.
(1953)
J.B. Goodenough et al.
Phys. Rev.
(1955)
J.H. Van Vleck
J. Chem. Phys.
(1935)
J.H. Van Vleck
J. Chem. Phys.
(1935)
W. Moffitt et al.
Ann. Rev. Phys. Chem.
(1956)
L.E. Orgel
J. Chem. Phys.
(1955)
O. Holmes et al.
J. Chem. Phys.
(1957)
F.C. Romeijn
Philips Res. Rep.
(1953)

There are more references available in the full text version of this article.

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The distribution of transition metal cations in spinels

Abstract

J. Chem. Phy.

Philips Res. Rep.

J. Chem. Phys.

Philips Res. Rep.

Phys. Rev.

J. Chem. Phys.

J. Chem. Phys.

Ann. Rev. Phys. Chem.

J. Chem. Phys.

J. Chem. Phys.

Philips Res. Rep.