ZnS precipitation: morphology control

ZnS is the most important base material for cathode-ray tube luminescent materials. In order to meet the requirements of various types of luminescent screen, routes to ZnS powder with adjustable particle morphology were investigated. The most important morphological parameters of ZnS phosphors are the particle size and the particle size distribution. Industrially, ZnS synthesis is performed by precipitation in an aqueous medium. Precipitation methods included in this study are homogeneous precipitation, precipitation in liquid crystal phase and the introduction of seeds. The powders received were processed to luminescent materials in a standard manner. The results are discussed in relation to raw ZnS powder properties as well as to the morphology and performance of the resulting annealed phosphor powders. From the methods investigated, the use of seed sols based on nanosized CuS, ZnS and S particles yielded the best results, namely, well-defined phosphor particles of micron-scale diameter.