PROCESSFOR MAKING AN OPTICALLY TRANSMISSIVE BODY

Abstract

An optically transmittant body of a ternary sulfide material such as calcium lanthanum sulfide is provided by concurrently precipitating from a nitrate solution of calcium and lanthanum, calcium carbonate and lanthanum carbonate. The precipitation reaction forms a homogeneous fine particle size starting powder of calcium carbonate and lanthanum carbonate powders. The starting powder is reacted with a sulfurizing agent such as hydrogen sulfide to convert such starting powder into a calcium lanthanum sulfide powder. The particle size of the homogeneous starting powder is sufficiently small to permit substantially complete and uniform conversion of such starting powder into the calcium lanthanum sulfide powder. The calcium lanthanum sulfide powder is then compacted into the desired form of the optically transmittant body and is subsequently sintered at an elevated temperature in an atmosphere of excess sulfur to increase the density of the material. An excess sulfur atmosphere is provided to prevent decomposition of the calcium lanthanum sulfide and to aid in the conversion of any residual calcium carbonate, lanthanum carbonate material present in the calcium lanthanum sulfide. The sintered calcium lanthanum sulfide material is then compressed at an elevated pressure and temperature providing the material of the optically transmittant body.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1KENNETH J. SAUNDERS