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The Physicochemical Properties and Synthesis Method of Inorganic Compound Bismuth Oxide

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Update time : 2020-08-03 11:27:23

What Is Bismuth Trioxide

The pure bismuth trioxide (bismuth oxide) has α type, β type and δ type. α type is yellow monoclinic crystals, 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 in acid but insoluble in water. Easily reduced to metallic bismuth by hydrogen, hydrocarbons, etc. δ-Bi2O3 is a special material with a cubic fluorite mineral structure. 1/4 of the oxygen ion position in its crystal lattice is vacant, so it has 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 have a purity of 99.15% or more. The main application objects are zinc oxide varistors, ceramic capacitors, and ferrite magnetic materials.


The Physical And Chemical Properties of Bismuth Trioxide

The properties of bismuth trioxide are yellow heavy powder or monoclinic crystals, odorless, and stable in the air. The density is 8.9 at 25/4°C, the melting point is 825°C, the boiling point is 1890°C under normal pressure, and the flash point is approximately 1890°C. This substance is soluble in hydrochloric acid and nitric acid, but insoluble in water. The color of the body changes to maroon after heating, and it still changes to yellow after cooling.

Synthesis Method of Bismuth Trioxide

1. To the bismuth nitrate solution (80~90 ℃), add dropwise an aqueous solution of sodium hydroxide without carbon dioxide to mix thoroughly. 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 is obtained.


2. Under a nitrogen atmosphere, add dropwise a 1.5mol/L sodium hydroxide aqueous solution without carbon dioxide to a 0.1mol/L bismuth nitrate solution dissolved in 1mol/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 to light yellow bismuth trioxide after being stirred in a hot solution. Decant 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 sufficient oxygen supply, the crucible should be placed in a large container and oxygen should be continuously supplied. The reaction temperature is 750~800℃, 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 precipitation of Bi2O2CO3, filter, wash, and dry. Place it in an aluminum boat and heat it in air at 650K for about 1.5 hours to obtain β-Bi2O3 substance.


5. Burn 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.


6. Use a small amount of dilute nitric acid to wash 16kg of 99.9% industrial bismuth surface, and then use conductive water to wash away the surface nitric acid. Then add 1:1 high-purity nitric acid (35kg nitric acid with a relative density of 1.42 plus 20L conductive water), add 1H, and continue to react for 10 minutes after the addition. After cooling slightly, filter, heat the filtrate to 65~70℃, evaporate and concentrate to a relative density of 1.9, cool to crystallize, and spin dry to obtain bismuth nitrate. Dissolve the obtained bismuth nitrate with conductive water into a dilute solution, it under stirring, let stand to completely precipitate the bismuth subnitrate, spin the precipitate with a centrifuge or filter with suction, then wash it with thermoelectric conductive water several times, filter with suction and dry , Crush, burn at 500℃ for 7~8h, grind after a little cooling, then burn for 4~5h, after cooling, 99.99% high purity bismuth oxide can be obtained.


Luoyang Trunnano Tech Co., Ltd (TRUNNANO) is a professional bismuth oxide powder with over 12 years experience in chemical products research and development. If you are looking for high quality bismuth oxide powder, please feel free to contact us and send an inquiry.

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