Madelung constant

Madelung constant

A numerical constant α_M in terms of which the electrostatic energy U of a three-dimensional periodic crystal lattice of positive and negative

point charges q₊, -q_-, N in number, is given by the equation below, where d is the nearest-neighbor distance between positive and negative charges and N is large. Knowledge of such electrostatic energies as given by the Madelung constant is of importance in the calculation of the cohesive energies of ionic crystals and in many other problems in the physics of solids. See Ionic crystals

Madelung constants for some common ionic crystals

		Madelung
	Crystal structure	constant, αM
	Sodium chloride, NaCl	1.7476
	Cesium chloride, CsCI	1.7627
	Zinc blende, α-ZnS	1.6381
	Wurtzite, β-ZnS	1.641
	Fluorite, CaF2	5.0388
	Cuprite, CuO2	4.1155
	Rutile, TiO2	4.816
	Anatase, TiO2	4.800
	Corundum, Al2O3	25.0312

The Madelung constants for a number of common ionic crystal structures are given in the table. For these cases d is chosen as the nearest-neighbor distance. See Crystal

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

Madelung constant

[′mä·də‚lu̇ŋ ‚kän·stənt]

(solid-state physics)

A dimensionless constant which determines the electrostatic energy of a three-dimensional periodic crystal lattice consisting of a large number of positive and negative point charges when the number and magnitude of the charges and the nearest-neighbor distance between them is specified.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.