METHOD FOR SYNTHESIS OF BISMUTH FERRITE NANOPOWDERS Russian patent published in 2021 - IPC B22F9/24 C01G29/00 C01G49/02 C30B29/24 B01F3/08 B01F5/08 B82B3/00 B82Y40/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a technology of synthesis of bismuth ferrite (orthoferrite) nanopowders in jet microreactors. The method of synthesis of bismuth ferrite nanopowders consists in supplying the initial components - a mixture of solutions of bismuth and iron salts in a component ratio corresponding with the stoichiometry of BiFeO₃ and an alkali solution with a molar volume concentration of 1 to 4 mol/L corresponding with the conditions of co-precipitation of components into a jet microreactor 1, wherein the synthesis of bismuth ferrite nanopowders is executed in two stages: at the first stage, bismuth and iron hydroxides are co-precipitated in the jet microreactor 1 by supplying solutions of the initial components in form of thin jets 100 to 800 mcm in diameter colliding in a vertical plane at a temperature between 20 and 30°С and a pressure close to atmospheric, followed by separation of particles from the suspension and washing alkali residues therefrom; at the second stage, the co-precipitated bismuth and iron hydroxides are dehydrated at a temperature between 420 and 600°С and an atmospheric pressure, the speed of the jets set at a value between 10 and 25 m/s, and the angle between the jets is set at a value between 70 and 120°, wherein the products of the reaction are separated and washed after the first stage using a drum-type vacuum filter 3 with a suspension suction area, repeated washing of the precipitation layer using nozzles 4, drying with atmospheric or heated air, separating the precipitation layer using a knife, and to implement the second stage, a drum furnace 5 installed slightly inclined to the horizon, rotating on annular bands supported by rollers 6, equipped with one or several infrared heaters 7, and an accumulator of finished product 8 are used.

EFFECT: invention allows simplifying the technology of synthesis of bismuth ferrite (orthoferrite) nanoparticles by reducing the temperature and pressure required for the first stage of synthesis; increasing the yield and selectivity of the process in the absence of impurity phases in the product; reducing energy consumption and ensuring continuity of the process with possibility of implementation thereof on an industrial scale; reducing capital costs for equipment; providing optimal conditions for high-speed reactions by maintaining stable and efficient hydrodynamic conditions of contacting of reagents, supplying reagents in a stoichiometric ratio, fast discharge of products of reaction and dehydration at optimal temperatures.

1 cl, 6 dwg