Synthesis of ZnS whiskers

One approach to improving the mechanical performance of a materials is to form a self-similar whisker reinforced composite. This is the approach we are developing for ZnS optical windows; however, it has necessitated the development of synthesis methods for ZnS whiskers. Recently, we reported an organometallic route to ZnS whiskers [1,2]. Here we report yet another synthesis route. This non-organic route involves the surface reaction of metallic zinc foil or wire in a flowing atmosphere of H₂S (T_max=350°C). The ZnS whiskers created at the zinc surface were characterized using SEM, TEM, SIMS and X-ray diffraction. After an 8 h 350°C thernal treatment, the whiskers were ZnS averaging 19.2 μm in length, aspect ratio 27. The whiskers are single crystal in nature, and appear to evolve through an oxide layer at the surface of the zinc substrate. Thermochemical analysis of the reaction was performed to establish the relative stability of ZnS and various oxide and sulfates, and these confirmed the experimental data. These calculations describe the effects of temperature and gas phase composition upon the thermochemical stability of ZnS and other solid phase reaction products. The calculations are exceedingly useful for determining and controlling the process parameters and for the evaluation of the experimentally observed products.