METHOD FOR PREPARING A CHARGE FOR GROWING FLUORIDE SINGLE CRYSTALS Russian patent published in 2021 - IPC C30B11/04 C30B29/12 

FIELD: chemical industry.

SUBSTANCE: invention relates to a chemical technology for preparing a charge for growing fluoride single crystals. The method includes mixing the starting components MeF₂-RF₃-PbF₂ where Me is Ca, or Ba, or Sr, R is REE, and PbF₂ is an oxygen absorber, heating and holding them, while Eu³⁺, or Ce³⁺, or Tm³⁺, or Nd³⁺ is used as R. The components are taken in a stoichiometric ratio: Me - 93%, R - 2%, PbF₂ - 5%, or Me - 96%, R - 2%, PbF₂ - 2%, or Me - 97%, R - 1% , PbF₂ - 2%, followed by their placement in a graphite crucible in the form of a "boat" with a cover made of the same material, then the crucible with the components is installed in a high-temperature vacuum furnace with a graphite heating unit and heated in it to a temperature of 200-250°С in vacuum, followed by holding for 3-4 hours, then heating the crucible with the components in a high-temperature annealing vacuum furnace to a temperature of 700-750°С in a vacuum atmosphere, followed by holding for 3-4 hours, heating the crucible with the components in a high-temperature annealing vacuum furnaces up to a temperature of 1000-1300°С in an excess vacuum atmosphere and holding for 6 h and holding in an excess atmosphere of hydrogen fluoride HF or tetrafluoromethane CF₄ for 6-8 hours and inertial cooling of the resulting cake to room temperature, while using a furnace and crucible that do not contain oxygen molecules in their material.

EFFECT: invention makes it possible to obtain high-quality solid cakes without the presence of impurities, solid cakes of the required mass and size to fill the entire volume of a graphite crucible mold during the synthesis of a single crystal from it (an increase in the bulk density of the initial components), solid cakes, during the synthesis of which there is no material shrinkage in the single crystal ( that is, the volume of the initial sinter is equal to the volume of the synthesized single crystal), to avoid violation of the stoichiometry of the melt, since the resulting solid sinter is completely used when melting into the crucible, and therefore, to obtain single crystals of uniform composition, to avoid the formation of a "fluidized layer" and, as a consequence, to exclude the entry of a finely dispersed mixture into the space of the heating unit.

1 cl, 3 dwg