METHOD OF PRODUCING POLYCRYSTALLINE OPTICAL ZINC SELENIDE Russian patent published in 2013 - IPC C30B28/12 C30B29/48 

FIELD: physics.

SUBSTANCE: method involves heating and evaporating starting material at temperature of 1050-1150°C, condensing vapour on a substrate heated to 950-1050°C at a rate of 0.2-0.8 mm/h, wherein cooling the apparatus with the grown workpiece is carried out in a controlled manner, where at below 900°C cooling is carried out at a rate of 50-100°C/h, in the range of 900-600°C - at a rate of 30-50°C/h and at above 600°C - inertial cooling to room temperature. To evaporate semi-volatile impurities, the starting material in form of powder or compact chips can be subjected to preliminary annealing in a medium of an inert gas, e.g. argon, at temperature of up to 1200°C for 10-15 hours. The invention enables to obtain the following optical properties with diameter of the grown workpieces of up to 500 mm and thickness of up to 50 mm: transmission at wavelength of 0.6 mcm - 30%, 1.06 mcm - 60%, 3-5 mcm 69%, 8-12.5 mcm - 71%. Birefringence in the optical material does not exceed 100 nm/cm.

EFFECT: high output of the product with improved optical properties.

2 cl, 2 ex