Behavior of Hydrogen at Charged Dislocation in NaCl

To study the structure of an edge dislocation core in an ionic crystal, we measured the amplitude dependence of internal friction by the automated Marx's composite oscillator method and the vibrational current caused by charged dislocations in a hydrogen-absorbed NaCl single crystal. The change of the sign of dislocation charge at the strain amplitude of 10-6 disappeared with absorption of hydrogen, while it was preserved using helium. These findings suggest that hydrogen exists as a positive ion in the dislocation core.