Influence of elastic stresses and temperature on the dislocation unpinning from the stoppers in KCl crystals

• Published in: Functional Materials
• Date: 2015
• Main Authors: Petchenko, G.A., Petchenko, A.M.
• Format: Article
• Language: English
• Published: НТК «Інститут монокристалів» НАН України 2015
• Subjects: Characterization and properties
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/119370
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Influence of elastic stresses and temperature on the dislocation unpinning from the stoppers in KCl crystals / G.A. Petchenko, A.M. Petchenko // Functional Materials. — 2015. — Т. 22, № 3. — С. 293-298. — Бібліогр.: 14 назв. — англ.

Impulse echo-method was applied to investigate, in the temperature range from 300 to 430 K at 7.5 MGz frequency, the dislocation absorption αd(σ) in KCl crystals as a function of statistic loading in the quasi-elastic strain range. It has been found that the temperature increase at stresses σ < σt (σt is the yield strength of a crystal) leads to the intensive dislocation unpinning). Consequently, concentration of stoppers, controlling their motion, sharply decreases and the effective length of oscillating dislocation segments increases. As a result of the experimental data processing the energy of the impurity atom binding with dislocation U₀ and quantity L characterizing a mean size of the dislocation cell was calculated. The experimental results were discussed within the framework of known dislocation theories.