Monodispersed and spherical ZnS for nano-grain optical windows
A method is provided for producing an article which is transparent to infrared radiation. The method includes the steps of (a) disposing a population of nanoparticles on a substrate, wherein the population of spherical nanoparticles has a population variance of less than 10% in at least one parameter selected from the group consisting of diameter and maximum dimension; (b) subjecting the nanoparticles to spark plasma sintering, thereby producing a sintered product; and (c) removing the sintered product from the substrate as a self-supporting mass.
1. An infrared imaging device which captures infrared images through an optical window, said window comprising a material derived by subjecting a population of spherical nanoparticles to spark plasma sintering, wherein the population of spherical nanoparticles has a population variance of less than 10% in diameter.
2. The infrared imaging device of claim 1 , wherein said nanoparticles comprise a material selected from the group consisting of metal sulfides and metal selenides.
3. The infrared imaging device of claim 1 , wherein said nanoparticles comprise a metal sulfide selected from the group consisting of zinc sulfide, strontium sulfide, calcium sulfide, lead sulfide, gallium sulfide, and calcium lanthanum sulfides.
4. The infrared imaging device of claim 2 , wherein said nanoparticles comprise zinc sulfide.
5. The infrared imaging device of claim 1 , wherein said nanoparticles have an average diameter within the range of about 10 nm to about 100 nm.
6. The infrared imaging device of claim 1 , wherein said nanoparticles have an average diameter within the range of about 30 nm to about 50 nm.
7. The infrared imaging device of claim 1 , wherein said nanoparticles are crystalline nanoparticles.
8. The infrared imaging device of claim 1 , wherein said material has nano-grains with an average maximum dimension within the range of about 100 nm to about 800 nm.
9. The infrared imaging device of claim 1 , wherein said material has nano-grains with an average maximum dimension within the range of about 220 nm to about 500 nm.
10. The infrared imaging device of claim 1 , wherein said material is optically transmissive over the wavelength range of 0.4 microns to 12 microns.
11. The infrared imaging device of claim 1 , further comprising:
a first antireflective coating disposed over said material, said antireflective coating comprising a material selected from the group consisting of yttria, silica, magnesium fluoride, calcium fluoride, zinc fluoride, zinc selenide, and hafnium oxide.
12. The infrared imaging device of claim 11 , further comprising:
a second antireflective coating disposed over said material, said second antireflective coating comprising a material selected from the group consisting of leaded glass and zinc selenide.
13. The infrared imaging device of claim 1 , wherein said imaging device is disposed on a missile, and wherein said window is disposed between said imaging device and the environment external to the body of said missile.
14. The infrared imaging device of claim 1 , wherein the population of spherical nanoparticles has a population variance in nanoparticle diameter of less than 5%.
15. The infrared imaging device of claim 1 , wherein the population of spherical nanoparticles has a population variance in nanoparticle diameter of less than 1%.
16. The infrared imaging device of claim 1 , wherein the population of spherical nanoparticles has a population variance in nanoparticle diameter of less than 3%.
17. The infrared imaging device of claim 1 , wherein said material has a Knoop hardness, with a 50 g load, which is greater than 235 kg mm −2 .
18. The infrared imaging device of claim 1 , wherein said material has a Knoop hardness, with a 50 g load, which is greater than 245 kg mm −2 .
19. The infrared imaging device of claim 1 , wherein said material has a Vicker's hardness, with a 1 kg load, which is greater than 245 kg mm −2 .
20. The infrared imaging device of claim 1 , wherein said material has a Young's Modulus of greater than 80 GPa.