Equilibrium vacancy concentration measurements on aluminum

Autor:	H. Peisl, R. Zitzmann, B. von Guérard
Rok vydání:	1974
Předmět:	Thermal equilibrium Materials science Condensed matter physics Enthalpy General Engineering Extrapolation Thermodynamics General Chemistry Thermal expansion Lattice constant Vacancy defect Melting point General Materials Science Diffractometer
Zdroj:	Applied physics. 3:37-43
ISSN:	1432-0630 0340-3793
DOI:	10.1007/bf00892332
Popis:	Thermal expansion on high purity aluminum has been measured to study defects in thermal equilibrium by the (ΔL/L 0−Δa/a 0) method. Measurements of the changes in macroscopic length ΔL and lattice parameter Δa were made from room temperature to 637° C. Length changes were measured by a laser interferometer and lattice parameter changes by a X-ray diffractometer technique on the same crystal at identical temperatures. At temperatures above 400° C ΔL/L 0 becomes greater than Δa/a 0, indicating the generation of a noticeable amount of new lattice sites due to vacancy formation. Extrapolation gives a vacancy concentration ΔN/N 0=9.8·10−4 at the melting point (660° C). The experimental findings can be explained by assuming formation of monovacancies and divacancies. Values for the enthalpy and entropy of formation for mono- and divacancies are given.
Databáze:	OpenAIRE
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