J. Phys. I France
Volume 6, Numéro 9, September 1996
Page(s) 1203 - 1216
J. Phys. I France 6 (1996) 1203-1216
DOI: 10.1051/jp1:1996124

Dilution Effects in a Spin Crossover System, Modelled in Terms of Direct and Indirect Intermolecular Interactions

H. Constant-Machado1, J. Linares1, F. Varret1, J.G. Haasnoot2, J.P. Martin3, J. Zarembowitch3, A. Dworkin4 and A. Bousseksou5

1  Laboratoire de Magnétisme et d'Optique URA 1531 CNRS, Université de Versailles, 78035 Versailles Cedex, France
2  Institute of Chemistry, Gorlaeus Laboratories, Leiden University, POB 9502, 2300 RA Leiden, The Netherlands
3  Laboratoire de Chimie Inorganique URA 420 CNRS, Université Paris Sud, 91405 Orsay Cedex, France
4  Laboratoire de Chimie Physique des Matériaux Amorphes URA 1104 CNRS, Université paris Sud, 91405 Orsay Cedex, France
5  Laboratoire de Chimie de Coordination UPR 8241 CNRS, 31077 Toulouse Cedex, France

Received 21 July 1995, revised 27 February 1996, received in final form 7 May 1996, accepted 10 May 1996

We have studied by 57Fe Mössbauer spectroscopy and magnetic measurements the spin transition exhibited by the series: , consisting of a spin-crossover iron(II) system diluted in a high-spin cobalt(II) matrix. We performed Monte Carlo simulations of the thermal variation of the high-spin fraction, using a two-level Ising-type Hamiltonian. A good agreement with experiment is obtained by the introduction of an indirect interaction of the spin-crossover units via the non-spin crossover unit, the origin of which is discussed in steric terms.

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