Preparation, composition, and mechanical properties of CVD polycrystalline ZnS.

• Beside the main phase of zincblende, a small amount of wurtzite is existed in CVD ZnS. • The mechanical properties of CVD ZnS were characterized with a slight variation of Zn/S ratio. • Zn 46.84 S 53.16 presents a high flexural strength of 133.8 MPa. • XRD, SEM, and Raman spectra of CVD ZnS were conducted. Polycrystalline ZnS samples with a slight composition fluctuation are grown by chemical vapor deposition (CVD) method, and their optical and mechanical properties and microstructure were investigated in detail. The CVD samples present a maximum transmittance of ∼73% in the 7–10 μm region. By changing the sulfur content, a maximum Knoop hardness of 2.375 GPa was found in the Zn 50.06 S 49.94 sample, while Zn 46.84 S 53.16 presents a high flexural strength of 133.8 MPa. The microstructural origin of this abnormal changing of mechanical properties was discussed according to the results of micrographs, XRD patterns and Raman spectra. The results suggest that beside the main phase of zincblende, a small amount of wurtzite is existed. This composited microstructure is responsible for the higher hardness and strength of CVD ZnS. [ABSTRACT FROM AUTHOR]