Tin oxide is white, light yellow or light gray tetragonal, hexagonal or orthorhombic crystal powder. The melting point is 1630℃, the boiling point is 1800℃, and it is also an excellent transparent conductive material. It is the first transparent conductive material put into commercial use. In order to improve its conductivity and stability, it is often doped and used, such as SnO2, Sb, F, etc.
The types of tin oxide substances include tin monoxide SnO and tin dioxide SnO2. Tin monoxide is black cubic crystal; its density is 6.446g/cm3 (0℃); it is insoluble in water but easily soluble in acid. Tin dioxide is the main component of cassiterite, white tetragonal crystal; melting point is 1630℃, and then sublimated at 1800~1900℃, density is approximately 6.95g/cm3; insoluble in water, hardly soluble in acid, in concentrated sulfuric acid long-term heating can dissolve. Tin monoxide is easily oxidized into tin dioxide when heated in the air. Disproportionation reaction will occur when heated when the air is isolated: 4SnO─→Sn3O4+Sn
Tin monoxide is difficult to dissolve in strong alkali solution, and the product has obvious reducibility. Tin dioxide is stable to air and heat, and eutectic with strong alkali to form soluble stannate. Tin monoxide can be prepared by co-heating tin (II) salt solution and strong alkali. Tin dioxide can be prepared by heating metallic tin in air or dissolving in concentrated nitric acid and then heating and dehydrating.
1. Sol-gel method
The sol-gel method has been successfully applied due to its product uniformity, high purity and low synthesis temperature. This method is also widely used in the preparation of nano tin oxide. The powder produced by the sol-gel method has the advantages of uniform particle size, high specific surface, high activity, and low firing temperature. However, due to the influence of surface tension during the preparation process, the nanoparticles are very easy to agglomerate together. In order to overcome this shortcoming, some researchers have recently developed methods such as vacuum drying, freeze drying and supercritical fluid drying in the gel drying process of the sol-gel method. Among them, the supercritical fluid drying method is the most eye-catching method, which can remove Surface tension and capillary action during the drying process.
2. Hydrothermal method
The hydrothermal method is a general term for chemical reactions carried out under high temperature and high pressure using aqueous solution as the reaction medium in a special closed reaction vessel. By heating the container, a special physical and chemical environment that cannot be obtained under normal pressure is provided for the reaction and crystallization of various precursors. Nanoparticles prepared by hydrothermal method have the characteristics of complete crystal grain development, small particle size, uniform distribution, less particle agglomeration, good dispersibility and pure composition, and the preparation process has low pollution, low cost and simple process, especially without the need for later stage The high-temperature treatment avoids the growth of crystal grains, the formation of defects and the introduction of impurities during the high-temperature treatment, and the prepared powder has higher sintering activity.
3. Arc gasification synthesis method
The production equipment of the arc gasification synthesis method is power supply equipment, pit reactor and dust collection equipment. The production process is to heat the refined tin to 500℃ in liquid form, and use an electric arc to heat it to above 2000℃ in a pit reactor. The violent arc gasification reaction can produce a large amount of tin oxide vapor, which is crystallized into ultra-fine particles after cooling, and collected by dust collection equipment to obtain mixed ultra-fine powder containing trace tin and a small amount of tin monoxide, and then burned in the air at high temperature , Make it oxidized to tin oxide to obtain high-purity ultrafine tin oxide powder.
Luoyang Trunnano Tech Co., Ltd (TRUNNANO) is a professional tin oxide powder with over 12 years experience in chemical products research and development. If you are looking for high quality tin oxide powder, please feel free to contact us and send an inquiry.
