What is the development of bismuth telluride?
Since the 21st century, with the development of global industrialization, the demand for energy has been increasing. In the past century, industrial consumption has been mainly fossil energy. Humans are consuming the limited energy resources accumulated in the earth's 500,000-year history, and conventional energy has been exhausted. The world's proven oil reserves can only be used until 2020, natural gas can only last until about 2040, and coal resources can only last for about 2300. Moreover, these two kinds of fossil fuels emit a lot of harmful substances such as CO2, SO2, NO, and NO2, which seriously pollute the atmospheric environment and lead to the greenhouse effect and acid rain. Causes global climate change, directly affects human health and quality of life, and seriously pollutes water and soil resources. Therefore, the development of new environmental protection energy substitute materials has been paid more and more attention by countries all over the world. Among them, the development of new and environment-friendly renewable energy and energy conversion technology has attracted great attention from developed countries in the world. The thermoelectric semiconductor is a pollution-free green energy product that directly converts thermal energy and electric energy by thermoelectric effect. Among them, thermoelectric power generation uses the Seebeck effect of thermoelectric materials to directly convert thermal energy into electrical energy without mechanical moving parts and chemical reactions. Thermoelectric refrigeration uses the Peltier effect; when current flows through thermoelectric materials, it discharges heat energy from the low-temperature end to the high-temperature end without a compressor or refrigerant such as Freon. Therefore, these two types of thermoelectric equipment have no vibration, no noise, no wear and tear, and no leakage are small in size, light weight, have a long service life, safety and reliable, and do not produce any pollution to the environment. They are ideal power supplies and refrigerators. Therefore, the US Department of Energy, Japan Space Agency, and other relevant departments of developed countries have included thermoelectric technology in the medium and long-term energy development plan, and China has also included thermoelectric technology in the large-scale development of new energy plan of the National Key Basic Research and Development Plan (973). In the 21st century, the global environment and energy conditions are deteriorating, and it is difficult for fuel cells to enter practical application, so thermoelectric technology has become a noticeable research and development direction. The thermoelectric semiconductor industry, as a new industry in the world, grows at a rate of more than double every year. At present, Bi2Te3-based thermoelectric semiconductor materials are the most important raw materials in the commercial thermoelectric industry. Commercial B i2Te3-based thermoelectric semiconductor materials are prepared from bismuth, tellurium, and selenium, which are by-products of the copper smelting industry, by directional growth according to a certain proportion and special doping. Thermoelectric semiconductor industrialization can extend the industry with purification and manufacturing as the main raw material to the most popular new materials and new energy high-tech industries in the world at present, which is of great significance for enhancing the added value of scarce raw materials and developing the processing and application technology of high-tech materials. Thermoelectric power generation is the application of the Seebeck effect in power generation technology, and the ZT value of materials determines its power generation efficiency. When the low-grade waste heat is less than 400℃, the ZT value of Bi2Te3-based thermoelectric materials is the highest, and its figure of merit can be as high as 3×10-3~6×10-3K-1, which is also the most mature in industrialization.
