DISLOCATION CHARGE IN ALKALI HALIDES DETERMINED FROM INTERNAL FRICTION AND PIEZOELECTRIC DEFECT MEASUREMENTS W.H. ROBINSON, J.L. TALLON and R.G. BUCKLEY J. Phys. Colloques, 46 C10 (1985) C10-521-C10-524 DOI: 10.1051/jphyscol:198510115