Geometry of Etch Pits in ZnS Crystals

Structure and Morphology of ACEL ZnS:Cu,Cl Phosphor Powder Etched by Hydrochloric Acid

“…The etch pits are triangular and have been reported to appear on the ͑112͒ and ͑112͒ faces of the sphalerite structure, having bases parallel to ͓110͔ and apices always pointing in the ͓111͔ direction, i.e., toward the ͑111͒ face ͑Zn face͒, which exhibits the pyramids. 33 In other words, the apices of the triangular etch pits point in the opposite direction to the ͓111͔ growth direction of the crystal, i.e., away from the ͑111͒ face ͑S face͒. 33 Because the direction in which the apices of the triangular etch pits point is determined by the polar etching behavior, it has been previously concluded that the crystallographic polarity remains unchanged throughout the whole particle and is independent of changes in the crystal structure and disorder.…”

“…33 In other words, the apices of the triangular etch pits point in the opposite direction to the ͓111͔ growth direction of the crystal, i.e., away from the ͑111͒ face ͑S face͒. 33 Because the direction in which the apices of the triangular etch pits point is determined by the polar etching behavior, it has been previously concluded that the crystallographic polarity remains unchanged throughout the whole particle and is independent of changes in the crystal structure and disorder. 34 Consequently, the triangular etch pits are identified with points of emergence of electrically charged dislocations, and they may be necessary but not sufficient for ACEL to be produced.…”