Transparent ZnS Ceramics by Sintering of High Purity Monodisperse Nanopowders

Abstract

International audienceWe report an efficient way of preparing transparent ZnS ceramics using the hot-pressing technique. It has been found that the transparency is highly dependent on the purity and the grain size distribution of the starting ZnS powders. Highly pure and monodisperse ZnS powders have been obtained by posttreatment of the precipitated powders in a H2S/N2 flow for 2 h at 600°C. The obtained ZnS ceramics show fully dense and homogeneous microstructure with average grain size of ~1 μm and smooth grain boundaries, leading to an excellent transmission of around 70% in the mid- and far- IR regions. The preparation technique described in this study is highly reproducible

Highly IR transparent ZnS ceramics sintered by vacuum hot press using hydrothermally produced ZnS nanopowders

“…The peaks at 1430 and 1120 cm −1 attributes to the S–O stretching vibrational mode . The peak at 700‐900 cm −1 corresponds to the Zn–O vibration mode . The intensities of these absorption bands were high for the ZnS nanopowders synthesized using raw powders with small S/Zn ratios (≤1.0), as shown in Figure A,B.…”

“…The broad absorption band at 1650 cm −1 corresponds to the H–O–H bending mode . The peaks at 1430 and 1120 cm −1 attributes to the S–O stretching vibrational mode . The peak at 700‐900 cm −1 corresponds to the Zn–O vibration mode .…”

“…Therefore, it is difficult to use ZnS ceramics produced by CVD in military applications and under harsh conditions that require high‐strength materials. Many attempts have been made to produce ZnS ceramics using the vacuum hot press (VHP) method because VHP‐synthesized ZnS ceramics exhibit better mechanical properties than CVD‐synthesized ZnS ceramics and can be produced at a low cost through a simple process . Furthermore, spark plasma sintering (SPS) has been employed to synthesize ZnS ceramics, as it allows the production of ZnS ceramics at a low sintering temperature with a short process time .…”

“…Many methods, such as the wet chemical precipitation method, the colloidal processing method, and the hydrothermal method, have been utilized to produce ZnS powders . Furthermore, ZnS powders must be annealed at high temperatures in various atmospheres to remove residual water– and oxygen‐related defects for obtaining ZnS ceramics without carbonate‐related absorption . However, annealing can change the structure of ZnS nanopowders from cubic to hexagonal, even at temperatures lower than 1020°C, leading to the degradation of the optical properties of the ZnS ceramics.…”

Effect of copper concentration on the physical properties of ZnS:Cu alloys prepared by chemical bath deposition

“…The bands around 2350 cm -1 are attributed to the absorption peak of CO 2 [24]. The spectral bands in the range of 1000-1200 and 1300-1400 cm -1 are the characteristics of S-O and Zn-O vibrational bands, respectively [25]. The absorption bands observed at 400-900 cm -1 are related to the Zn-O vibration [24].…”