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The advanced information about bismuth oxide

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Update time : 2019-08-23 09:54:00
Bismuth oxide overview
The bismuth oxide is a pale yellow powder at normal temperature, and is orange when heated, and continues to heat to a reddish brown color, which still turns pale yellow after cooling. Bismuth oxide is insoluble in alkali and water, but soluble in acid to form a phosphonium salt, and is easily reduced by C and CH4, and has a melting point of 824°C and a boiling point of 1890°C. Cerium oxide mainly exists in four crystal forms of α, β, γandδ, where in α-BiO3 is monoclinic, β-BiO3 is tetragonal, and α-Bi2O3 and β-Bi2O3 are cubic crystals. Each crystal form of yttrium oxide has its special structure and properties. For example, the band gap can be changed from 2eV to 3.96eV due to the phase composition, where in the band gap of the α phase is 2.85eV, and the band gap of the β phase is 2.58ev.
The density of yttrium oxide also varies with the crystal form: monoclinic crystals are 8.2 g·cm3, and tetragonal crystals are 8.55 g·cm3 cubic crystals of 8.9 g·cm3. The monoclinic structure of α-BiO3 is a low temperature stable phase, while the δ-BiO3 with a cubic structure is a high temperature stable phase, and the other two crystal forms are metastable state crystal forms.
Method for preparing nano-cerium oxide
At present, researchers have developed a variety of methods for the preparation of nano-cerium oxide, which can be summarized as solid phase, gas phase and liquid phase. In recent years, through continuous improvement of related technologies, researchers have prepared a growing number of nano-cerium oxides with different morphologies. Compared with the previous performance, the performance of these nano-cerium oxides has not been greatly improved, and its application range is constantly expanding. The following is a brief analysis of the preparation methods of nano-cerium oxide by three methods: solid phase method, gas phase method and liquid phase method.
(1) Solid phase method
The solid phase method is a relatively traditional powder preparation process, usually the reaction reagent is reacted in a solid phase, the reaction conditions are easily achieved, and the reaction process is not complicated, but the disadvantage is that the obtained product is relatively easy to form agglomeration, and the particle is the size is not uniform enough. In some industrial production areas, this preparation method is still mostly chosen because of its low quality requirements for the product.

In the preparation of nano-cerium oxide, it is generally selected that several materials participating in the reaction are mixed, ground, calcined, etc. at a certain temperature, and finally the desired nano-cerium oxide material can be obtained. For example, Hong Weiliang et al. thoroughly and uniformly mix (BiNO3)3·5H2Oand NaOH, grind it after adding a certain dispersant, then heat it in a water bath while maintaining the temperature at 60°C, and finally obtain a solution after a series of treatments. The nano cerium oxide required has a polygonal shape and a particle size of about 60 nm.

(2) Gas phase method
The gas phase method refers to a method of preparing a desired nanomaterial by subjecting a substance to a physicochemical reaction in a gas state. Since the gas phase method is carried out at a high temperature and the liquid is lacking during the reaction, this method is suitable for the preparation of nano powders. The product prepared by gas phase method has small particle size, light agglomeration degree, high purity and easy control of product components, but the reaction conditions are difficult to control, and the reaction equipment has strict requirements, so this method is not easy to realize.

The spray-combustion method is an important gas phase method. The principle is that the metal is heated to melt it until it generates an aerosol, and then in the reaction furnace, a strong oxidation reaction occurs by burning fine metal objects, thereby The nano metal oxide powder is formed by the high pressure gas stream. For example, Kim et al. successfully synthesized B-Bi2O3 nanowires with a diameter of about 30-90 nm at a certain temperature and continued to raise the temperature. They obtained a BiO3 film-like structure.

(3)Liquid phase method
The liquid phase method is a nanomaterial preparation method with the most mature technology and the widest application range. The liquid phase method can selectively prepare nanomaterials having different microscopic morphology and material composition, and the uniformity of the prepared nanomaterials is generally good. However, this method has the disadvantage of easily introducing impurities into the preparation process, and therefore the method is generally not suitable for applications where the purity of the product is high. With the introduction of some new technologies such as microwave radiation and ultrasonic methods, the technology for preparing nanomaterials by liquid phase method has also made great progress. In general, there are many types of liquid phase methods, mainly including freeze-drying method, hydrothermal synthesis method, radiation chemical synthesis method, precipitation method, sol-gel method, microemulsion method, and spray method.

Luoyang Trunnano Tech Co., Ltd (TRUNNANO) is a professional Bismuth Oxide Bi2O3 powder manufacturer with over 12 years experience in chemical products research and development. If you are looking for high quality Bismuth Oxide Bi2O3 powder, please feel free to contact us and send an inquiry.

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