Zeitschrift für Physik B Condensed Matter

, Volume 96, Issue 3, pp 325–332

Crystal-field induced dipoles in heteropolar crystals I: Concept

  • Mario Birkholz
Article

DOI: 10.1007/BF01313054

Cite this article as:
Birkholz, M. Z. Physik B - Condensed Matter (1995) 96: 325. doi:10.1007/BF01313054

Abstract

The electrostatic part of the internal energy of heteropolar crystals is largely assumed to be purely of the Coulomb or monopole type. Here, it is argued, ions in a crystal lattice may not only bear a net charge, but also higher electrostatic moments. This applies explicitly for dipole moments. Dipoles are assumed to occur only for ions on lattice sites where the point symmetry allows a non-vanishing crystal electric field to cause a polarization. Infinite lattice sums that account for the electrostatic interaction between point charges and dipoles are given, with the Madelung constant being the first of them in a more general Taylor expansion. An expression for the binding energy of heteropolar solids is hereby presented. The share due to induced dipoles is always negative if dipole-dipole interactions are neglected, i.e. it increases the strength of crystal binding. The concept, which is developed for crystals of arbitrary symmetry is explained on the basis of the examples (i) sphalerite (ZnS), (ii) pyrite (FeS2), (iii) rutile (TiO2), and (iv) orthorhombic La2CuO4.

PACS

05.50.+q61.50.Lt

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Mario Birkholz
    • 1
  1. 1.Ingenieurbüro für SolartechnikBerlinGermany