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 aut omated Marx's composite oscillator method and the vibrational current caused by charged dislocations in a hydrogen-absorbed NaCl single crys tal. The change of the sign of dislocation charge at the strain amplit ude of 10(-6) disappeared with absorption of hydrogen, while it was pr eserved using helium. These findings suggest that hydrogen exists as a positive ion in the dislocation core.