Zur Untersuchung von Versetzungen mit Hilfe der magnetischen Kernresonanz

Abstract

The line width of the nmr signal is obtained for a statistical distribution of distances and orientations of dislocations as a function of the dislocation density. The quadrupolar part of the line width increases proportional to the root of the dislocation density in the case of first order distortion but is proportional to the dislocation density itself in the case of second order distortion. The total line width passes through a maximum within the range of first order distortion and approaches the value of the undistorted central line which arises from magnetic dipole interaction when the dislocation density becomes sufficiently large. The intensity decay of the nmr signal connected with this line width behaviour will also be presented.

In the range of second order distortion the total line width is determined by the constant dipole interaction and the quadrupole interaction of the central line which depends on the dislocation density. Under the assumption of a Gaussian distribution for the line shape a simple expression for this width can be obtained.

The calculations are checked for the case of first order distortion by measurements on the Na²³ and Cl³⁵ nmr signals of NaCl single crystals and for the case of second order distortion by measurements on the J¹²⁷ signal of KJ single crystals.