Study on the effects of crisp layer on optical and mechanical properties of CVD ZnS

CVD ZnS was prepared by chemical vapor deposition, and multispectral ZnS was obtained by hot isostatic pressing treatment. XRD, transmittance and bending strength were used to characterize the samples. The effects of CVD ZnS crisp layer on the optical and mechanical properties of materials before and after hot isostatic pressing were studied systematically. It was found that there were relatively few hexagonal phases in the standard ZnS crisp layer, with stress concentration, grain size significantly larger than the normal zone and the bending strength lower than the normal zone 10%. When the wavelength is less than 660 nm, the transmittance of the crisp layer can be higher than that of the normal region. When the wavelength is greater than 660 nm, the transmittance of the crisp layer is lower than that of the normal region, with a difference of 11% at 2 μm. The transmittance of the far-infrared region was basically same. After hot isostatic pressing treatment, the stress concentration in the crisp layer and the hexagonal phase of each layer was eliminated. The grain size tended to be uniform, but the bending strength of the crisp layer was still lower than that of the normal area 4%. The overall transmittance was significantly improved, and the transmittance of the crisp layer was higher than that of the normal area. The difference gradually decreased with the increase in wavelength, and the difference was 3% at 450 nm.