Vacancy relaxation in cubic crystals

• Published in: The Journal of physics and chemistry of solids Vol. 12; no. 3; pp. 260 - 264
• Main Authors: Girifalco, L.A., Weizer, V.G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.1960
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/0022-3697(60)90047-0

The configuration of the atoms surrounding a vacancy in four face-centered cubic and three body-centered cubic metals has been computed, using a pairwise, central-force model in which the energy of interaction between two atoms was taken to have the form of a Morse function. Only radial relaxations were considered. The first and second nearest-neighbor relaxations for the face-centered systems were found to be: Pb (1.42,−0.43), Ni (2.14,−0.39), Cu(2.24,−0.40) and Ca (2.73,−0.41, expressed in percentages of normal distances. For the body-centered systems the relaxations out to the fourth nearest neighbors to the vacancy were: Fe (6.07,−2.12, −0.25, −), Ba (7.85, −2.70, 0.70, −0.33) and Na (10.80, −3.14, 3.43, −0.20). The positive signs indicate relaxation toward the vacancy and the negative signs indicate relaxation away from the vacancy. The energies of relaxation (eV) are: Pb (0.162), Ni (0.626), Cu (0.560), Ca (0.400), Fe (1.410), Ba (0.950) and Na (0.172). An estimate of the ease of motion of the atoms surrounding a vacancy in sodium was made, and it was concluded that N achtrieb's relaxion concept is probably valid in sodium.