| Abstract: | The influence of the growing atmosphere on the mechanical properties was investigated on LiF and NaCl single crystals. The growing atmospheres were air or vacuum and argon, respectively. In a wide temperature range the air grown crystals have a higher flow stress and a smaller activation volume. Besides, the dislocations are less mobile. The differences arise probably from the OH−-ions, which were found in a considerable concentration in the air grown material. The OH−-ions may create lattice distortions by themselves or by the formation of different complexes with the divalent cation impurities. In this way the density of thermal and athermal obstacles for the dislocation motion increases. |
