Coated (core-shell) nanoparticles for nanocomposite optical ceramics

A method for producing coated nanoparticles for use in a nanocomposite optical ceramic (NCOC) material, the method comprising:

• providing a first quantity of uncoated nanoparticles of a first material;
• coating the first quantity of uncoated first material nanoparticles with a second material to form coated nanoparticles, wherein:
• the first material and the second material are mutually insoluble;
• the first material and the second material each have a transmissivity of at least 80% for an intended wavelength;
• the first material and the second material have a difference in index of refraction of less than 25%;
• the first material and second material have grains with diameters of less than 1/20th the intended wavelength;
• the second material coating on the first material nanoparticles is up to 50 nm thick;
• and
• dry pressing and compacting, sintering, and hot isostatic pressing the coated nanoparticles to form the NCOC material, wherein the NCOC material contains no more than 0.01% voids per unit volume;
• wherein the first material and the second material are selected to limit NCOC grain growth such that the NCOC exhibits grain growth of no greater than 20% when exposed to a temperature of −1400° C. to 1600° C. for one hour.