| Autor: |
von Guérard, B., Peisl, H., Zitzmann, R. |
| Zdroj: |
Applied Physics B: Lasers and Optics; January 1974, Vol. 3 Issue: 1 p37-43, 7p |
| Abstrakt: |
Abstract: 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: |
Supplemental Index |
| Externí odkaz: |
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