METHOD FOR PRODUCING BIPHASIC CERAMIC LUMINOPHORS FOR WHITE LEDS Russian patent published in 2023 - IPC C09K11/80 C30B29/28 C09K11/59 

FIELD: chemistry.

SUBSTANCE: invention relates to the field of luminophor materials for the needs of photonics, in particular, to heat-resistant solid-state colour converters, and can be used for producing functional materials both for compact and energy-efficient lighting apparatus and for high-power LED systems, from portable projectors, endoscopes, and displays to cinema projectors and laser television sets with a more than 100-inch diagonal, lighting equipment for automotive and aircraft engineering, mega structures (airports, stadiums, train stations, routes, and tunnels), etc. Proposed is a method for producing biphasic ceramic luminophors for white LEDs, including the stage of joint high-energy milling of powders of initial oxides Y₂O₃, Al₂O₃, and CeO ₂ and sintering additives in the form of MgO in the amount of 0.08 wt.% and tetraethoxysilane (TEOS) in the amount of 0.8 wt.% as a source of SiO₂, wherein the milling is performed in a planetary ball mill using Al₂O₃ grinding bodies in an ethanol medium for 12 hours while gradually increasing the rotation speed to 300 rpm for the first 30 min. A poorly aggregated powder system of the stoichiometric composition Al₂O₃-Ce³⁺:YAG with a content of cerium ion within 0.05 to 0.15 at.% Ce³⁺ and an aluminium oxide phase 10 to 20 wt.% Al₂O₃ is formed, dried at a temperature of 70 °C to a constant mass, followed by granulating said system through a sieve with an effective cell size 200 mesh and annealing in an air atmosphere at 600 °C for 4 h. The resulting material is then pressed uniaxially under a pressure of 35 MPa, then isostatically under a pressure of 250 MPa for 5 min. The compacts loaded into the vacuum sintering unit are heated under an external pressure of 5.0·10^-4 Pa at a rate of 10 °C/min to the temperature of 1,000 °C, then at a rate of 5 °C/min to the temperature of 1,400 °C, and at a rate of 2 °C/min to a temperature of 1,750 to 1,775 °C and held at this temperature for 8 to 12 hours, followed by annealing the resulting sample in an air atmosphere.

EFFECT: possibility of producing biphasic ceramic luminophors Al₂O₃-Ce³⁺:YAG with excellent thermal properties and a high photoluminescent response, long operating life and a high resistance to the effect of oxygen, carbon dioxide, chemicals and moisture, making this type of materials effective in the development of modern photonics in lighting.

3 cl, 1 dwg, 1 tbl