What is bismuth oxide? Bismuth oxide is an inorganic compound with the molecular formula Bi2O3. The pure product has α type, β type, and δ type. α type is yellow monoclinic crystal, relative density 8.9, melting point 825 ℃, soluble in acid, insoluble in water and alkali; β type is bright yellow to orange, tetragonal crystal system, relative density 8.55, melting point 860 ℃, soluble Acid, insoluble in water. It is easily reduced to metallic bismuth by hydrogen, hydrocarbons, etc.; δ-Bi2O3 is a special material with a cubic fluorite ore structure. 1/4 of the oxygen ion position in its crystal lattice is vacant, so it has a very high oxygen ion conductivity. The main application objects of bismuth oxide are electronic ceramic powder materials, electrolyte materials, photoelectric materials, high-temperature superconducting materials, and catalysts. As an important additive in electronic ceramic powder materials, bismuth oxide is generally required to be above 99.15% purity. The main application objects are zinc oxide varistors, ceramic capacitors, and ferrite magnetic materials.
Bismuth oxide preparation 1. To the bismuth nitrate solution (80-90°C), dropwise add a carbon dioxide-free sodium hydroxide aqueous solution and mix. The solution remains alkaline during the precipitation process, and a white, volume-swelling bismuth oxide hydrate Bi(OH)3 precipitates. This solution is heated and stirred for a short time to be dehydrated into yellow bismuth trioxide. After washing with water decantation, filtering, and drying, the finished bismuth oxide product is obtained. 2. Under a nitrogen atmosphere, add dropwise a 1.5 mol/L sodium hydroxide aqueous solution without carbon dioxide to a 0.1 mol/L bismuth nitrate solution dissolved in 1 mol/L nitric acid (at 80-90° C.) to mix them. The solution remains alkaline during precipitation. Although a white, volume-expanded bismuth oxide hydrate Bi(OH)3 precipitates, it is dehydrated and turned into light yellow bismuth trioxide after being stirred in the hot solution for a while. Decant and wash 15 times with water without air and carbon dioxide, filter and dry. 3. After the metal bismuth is put into the graphite crucible and melted, under the oxygen flow, an arc is formed between the graphite electrode and the metal surface to heat and oxidize. To ensure an adequate supply of oxygen, the crucible should be placed in a large container and oxygen should be continuously supplied. The reaction temperature is 750-800°C, and β-bismuth trioxide with a purity of 99.8% or more is quickly generated. After the product is quenched in water or on a cold metal plate, a high-temperature phase β-type product can be obtained. 4. Slowly add Bi(NO3)3·5H2O acidic solution (20g dissolved in 2mol/L HNO3) to the excess sodium carbonate solution and stir vigorously. Obtain the Bi2O3CO3 precipitate, filter, wash, and dry. Place it in an aluminum boat and heat it in the air at 650K for about 1.5 hours to obtain β-Bi2O3 5. Burn the bismuth subnitrate at 400～500℃ to remove NO3- ions for about (3～4h): 2BiONO3=Bi2O3+NO+NO2+O2 The burning is over, and after cooling, all turn into lemon yellow, which is the finished product.
Bismuth Oxide application Used to prepare bismuth salt; used as electronic ceramic powder material, electrolyte material, photoelectric material, high-temperature superconducting material, catalyst. As an important additive in electronic ceramic powder materials, bismuth oxide is generally required to be above 99.15% purity. The main application objects are zinc oxide varistors, ceramic capacitors, and ferrite magnetic materials; as well as glaze rubber compounding agents, medicines, Red glass compounding agents, etc.
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