What is bismuth oxid?
The pure bismuth trioxide (nanopowder ) is classified into three types: a, b and d. A type is yellow, monoclinic crystals with a melting point of 825. It’s soluble in both acid and water but insoluble in alkali. b type is bright yellow to orange tetragonal crystalline system with relative density 8.55. Melting point 860. Soluble in acid, but insoluble when mixed with water. Hydrogen and hydrocarbons can be used to reduce the material into metallic bismuth. The cubic fluorite structure of dBi2O3 makes it a unique material. The crystal lattice of d-Bi2O3 is void in 1/4, which gives it a high oxygen conductivity. Bismuth Oxide is mainly used for electronic ceramic powders. It can also be used as photoelectric materials, superconducting high temperature materials and catalysts. Bismuth is an essential additive in electronic ceramic materials. Its purity must be at least 99.15%. Main application objects include ceramic capacitors, zinc oxide varistors, and ferrite magnet materials.
The method for synthesis of bismuth dioxide
The aqueous sodium solution without carbon dioxide, which is a solution of sodium chloride in water, was mixed with the bismuth-nitrate solution at 80-90degC. The solution stays alkaline and the white volume-swelling Bismuth Oxide Hydrate Bi(OH)3 is precipitated. This solution is heated, stirred and dehydrated to yellow bismuth trioxide. After decantation of water, filtering and drying the product bismuth dioxide is obtained.
A 0.1 mol/L Bismuth Nitrate Solution dissolved in 1 Mol/L Nitric Acid (at 80 to90deg C.) was dropped into a 1.5 mol/L NaOH aqueous syringe to mix the two solutions. During precipitation, the solution remains alkaline. The white, volume-expanded, bismuth oxide trihydrate Bi(OH3) will precipitate, but it will dehydrate and turn into light yellow after stirring the hot solution. Wash 15 times in water without carbon dioxide or air, then filter and dry.
After melting the metal bismuth, an arc forms between the graphite and metal surfaces to heat and oxidize. For a continuous supply of oxygen to the crucible, it should be kept in a large vessel and placed on agitator. The reaction is carried out at a temperature of 750-800degC and the b bismuth trioxide is generated quickly with a purity level of 99.8%. A high-temperature phase B-type product is obtained by quenching the product in water or using a cold metal surface.
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