Sintering and optical properties of transparent ZnS ceramics by pre-heating treatment temperature

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

“…Therefore, ZnSO 4 in the Zn source could be responsible for the formation of these defects because it contains Zn–O and S–O components. The O–H stretching band at 3400 cm −1 , which was previously observed for ZnS nanoparticles, was not observed for the ZnS nanopowders produced in this study.…”

“…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.…”