Determination of Dislocation Densities Through Nuclear Resonance Studies

Studies of quadrupolar effects of mixed alkali halide on nuclear resonance previously reported for Na in NaCl–NaBr have been extended to Br in KBr–NaBr. Amplification factor for e Q q is thus derived and making use of this factor densities of dislocation are determined for a series of plastically deformed crystals of KBr. Although the effects of the screw and edge dislocations are additive for the broadening of the spectral line, their contributions to the net shift of the center of gravity of the line are in the opposite directions for H 0 //[100]. Hence the two kinds of dislocation are separable in density through the measurement of the breadth and asymmetry of the spectral line. Extrapolation to zero strain shows that for an undeformed crystal screw and edge dislocations are nearly balanced in number and their total density lies around 4×10 8 cm -2 . Linear Compression more favors the production of screw dislocations than that of edge dislocations and the density of each type dislocation increases quite linearly with strain up to fourty percent deformation. For the heaviest deformed sample the total dislocation density achieved was about 3×10 9 cm -2 .