Light Scattering by Single Crystals of Potassium Chloride

Light scattering by crystals of potassium chloride grown at the Harshaw Chemical Company and at the Naval Research Laboratory was measured. Scattering by the Harshaw crystals varies with crystal orientation while scattering from the NRL crystals does not. The major part of the Harshaw crystal scattering is attributed to vacancy-impurity clouds around dislocations which have the scattering pattern of cylinders with ${\text{5×10}}^5\mathrm{\hspace{0.17em}\AA }$ length, radius 100–500 Å, and axis parallel to (100) directions. The major part of the NRL crystal scattering is attributed to impurity precipitates which have the scattering pattern of spheres 1400–1600 Å in diameter. Air quenching of the crystals to room temperature from temperatures up to 650°C produced marked changes in the scattering. The results of the quench treatments are tentatively interpreted in terms of the migration of defects.