Bismuth and its compounds have some special properties, making them widely used in electric light source, aerospace, electronics industry, nuclear technology, superconducting technology and so on. Table 1 lists some of the main uses of the current cockroaches. However, due to the scarcity of strontium-rich minerals, the separation and extraction of hydrazine is difficult, resulting in the high cost of strontium and its compounds, thus affecting its application.
Table 1 Main application areas of é’ª
Category use
Scandium oxide purity> 99.9% efficient multi-laser; a solid electrolyte; special ceramic intermediate Sc-Al alloy most effective modifier of an aluminum based alloy; production manufacturing missiles and spacecraft, automobiles, ships and other special alloy
Metal é’ª Purity >99.99% Optical Engineering - High Power Metal Halide Lamp, Solar Battery; Nuclear Energy Shielding for High Energy Radiation
1.1 new power source materials and optical materials scandium as source material, metal halide lamp made of scandium iodide (ScI3) and scandium foil - sodium scandium, well into the commodity market. The lamp is a halide discharge lamp. Under high voltage discharge, the sodium and helium atoms in the NaI/ScI3 tube are excited. When jumping from the excited state of the high energy level to the lower energy level, the radiation is emitted. Wavelength of light. The spectrum of sodium is 589~589.6nm yellow light, the spectrum of strontium is near ultraviolet and blue light of 361.3~424.7nm, and the two lines of strontium and sodium are just close to sunlight. Back to the ground state, the strontium and sodium atoms can be synthesized with iodide, so that the cycle can maintain a high atomic concentration in the lamp tube and prolong its service life. A sodium lamp with the same illumination is 80% more energy efficient than ordinary incandescent lamps, and its service life is 5000~25000hr. Because of its high luminous efficiency, good light color, power saving, long service life and strong ability to break fog, it can be widely used in TV cameras and squares, stadiums, and road lighting. It is called the third generation. light source. The popularity of halogenated lamps in the United States has exceeded 50%. The annual output of high-pressure sodium lamps exceeds 10 million, and the number of products in Japan exceeds 10 million. The amount of antimony is more than 40Kg. Our country started late in this respect, but it has also implemented the “big change of lights†plan. The development and popularity of global halogen lamps is expanding, and the demand for antimony will become more urgent.
The cadmium gallium garnet (GSGSS) was prepared by adding Sc 2 O 3 with a purity of 99.9 to 99.99% to yttrium gallium garnet (GGG), and the emission power of the latter was three times higher than that of the former. GSGG can be used in anti-missile defense systems, military communications, submarine water lasers, and industrial applications. The main applications are the United States and Japan.
The secondary light refractive index of the Sn 2 O 3 -containing LiNbO 3 crystal is reduced, and is suitable for manufacturing a parameter frequency selector, a waveguide, and a photoconductive switch. The addition of yttrium to optical glass, silicate glass, and borosilicate improves the refractive index of the glass and improves the reflective properties. Barium fluoride glass can be used to fabricate optical fibers in the mid-infrared region of the spectrum.
1.2 The new niobium- containing alloy material has a very magical alloying effect on aluminum alloy. As long as a few thousandths of niobium is added to the aluminum, a new Al3Sc phase is formed, which acts as a metamorphism on the aluminum alloy, causing the structure and properties of the alloy to occur. obvious change. Adding 0.2%~0.4%Sc can increase the recrystallization temperature of the alloy by 150~200OC, and the high temperature strength, structural stability, weldability and corrosion resistance are obviously improved, and the embrittlement which is easy to occur during long-term work at high temperature can be avoided. phenomenon.
Through the addition of trace amounts of bismuth, it is hoped that a series of new-generation aluminum alloy materials, such as ultra-high strength and high-toughness aluminum alloy, new high-strength corrosion-resistant weldable aluminum alloy, new high-temperature aluminum alloy, high-strength anti-intermediate, will be developed on the basis of existing aluminum alloys. Aluminum alloys for sub-irradiation, etc., have very attractive development prospects in aerospace, aviation, ships, nuclear reactors, light vehicles and high-speed trains. According to reports, the earliest and deepest research in this area in Russia has developed a series of excellent aluminum alloys, and is moving towards promotion and industrial production. The 1420 alloy has been widely used as a structural member for the MiG-29, MiG-26 aircraft, Tu-204 passenger aircraft and Jacques-36 vertical landing aircraft. The 1421 alloy is also used in the form of extruded profiled materials for the Antonov conveyor as the longitudinal beam of the fuselage. In addition, the United States, Japan, Germany and Canada, as well as China, South Korea, etc. have also begun research on niobium alloys. In recent years, the United States has used bismuth aluminum alloys for the manufacture of welding wire and sports equipment (such as baseball and softball bats, hockey sticks, bicycle beams, etc.). Baseball bats and softball bats made of bismuth alloy have been used in many world competitions and summer. Used in the Olympic Games.
Since the melting point of ruthenium (1540 ° C) is much higher than the melting point of aluminum (660 ° C), the density of ruthenium (3.0 g / cm 2 ) is similar to the density of aluminum (2.7 g / cm 3 ), and it has been considered to use yttrium instead of aluminum. Certain structural materials in rockets and spacecraft. U.S. requires spacecraft structural materials research should also have high strength and corrosion stability at 920 ℃ material and smaller than important, it is believed that a titanium alloy and scandium, scandium magnesium alloys having a high melting point, low specific gravity, and One of the ideal materials for high strength and other characteristics. Tantalum is also an excellent modifier for iron . A small amount of niobium can significantly increase the strength and hardness of cast iron. Tantalum can also be used as an additive for high temperature tungsten and chromium alloys.
1.3 Special ceramic bismuth oxide is much more expensive than other metal oxides with similar properties, so it is not very popular in ceramics. However, cerium oxide has special applications in some advanced ceramics due to its unique properties, the most prominent of which are as stabilizers for zirconia and compacting aids for silicon nitride and for the synthesis of specific ferroelectric ceramics. In addition, niobium can also be used to modify silicon carbide and aluminum nitride.
1.3.1 Zirconium oxide stabilizers Zirconia-based electrolytes are used in many electrochemical devices. The addition of some specific oxides to zirconia stabilizes its cubic or tetragonal phases to form oxygen ion holes. The oxygen ion conductance of this electrolyte is greatly increased over a range of temperatures and oxygen partial pressures and can be used to develop oxygen sensors. This oxygen sensor device can be used for monitoring the combustion process in the metallurgical industry and as a solid oxide fuel cell (SOFC). The fuel cell is a new type of battery that directly converts fuel energy into electrical energy. It has a high energy conversion rate and is considered to be one of the new energy sources of the 21st century. It is of great significance to overcome the energy crisis facing humanity. Following the SOFC is the fuel cell phosphate and molten carbonate fuel cell developed third generation solidified battery, high reliability, high energy ratio of mass and energy volume, simple structure and less pollution, etc. It has become the focus of the development of countries. [next]
The current solid electrolyte mostly uses ZrO 2 (YSZ) with 8 mol% Y 2 O 3 as a stabilizer, and the electric conductivity at 1000 ° C is 0.16 S/cm. 6~10mol% of cerium oxide can stabilize the cubic phase of zirconia and produce high ionic conductivity at 800~1000 °C. In the ZrO 2 (SSZ) electrolyte in which Sc 2 O 3 is used as a stabilizer, the maximum oxygen ion mobility is obtained when 8 mol% of Sc 2 O 3 is contained, and the electric conductivity at 1000 ° C is 0.38 S/cm. The conductivity of the tetragonal phase Sc2O3 stabilized ZrO 2 (2.9 mol% Sc 2 O 3 ) is also higher than that of yttrium oxide or YSZ. Some people tested SSZ (11 mol% Sc 2 O 3 ) at 1000 ° C for 2,000 hours and found that the conductivity of this electrolyte was stable at 0.31 S/cm. The dispersion of alumina particles on the surface of the SSZ reduces its ionic conductance, but increases its bending strength by 40-50%, making it more suitable for the development of SOFC. SOFC plates developed in Japan, to SSZ (8mol% Sc 2 O 3 ) Alternatively YSZ (8mol% Sc 2 O 3 ), so that the power density of the SOFC is increased to 1.6W / cm 2, which is 1.5 to 2 times, significantly Increased the availability of SOFC. SSZ is rarely used at temperatures above 1100 to 1200 ° C, where its conductivity and mechanical properties decrease over time.
The zirconia oxygen sensor based on tetragonal yttria stabilized has been commercialized and applied to some field controls, but has not been widely used. SSZ (4.5 mol% Sc 2 O 3 ) exhibits good corrosion resistance when used in thermal insulation coatings for gas turbines and diesel engines. SSZ is a promising structural material due to its relatively low density, low vapor pressure and solid phase stability.
1.3.2 Silicon nitride dense auxiliaries The addition of yttrium oxide as a densifier in silicon nitride can improve its high temperature mechanical properties compared with the addition of other oxides. This yttria-densified silicon nitride (Sc 2 O 3 -Si 3 N 4 ) also has high oxidation resistance in a dry or humid environment. Cerium oxide is also a good sintering aid for silicon nitride, which is less prone to form oxynitrides of tetravalent metals and silicon, thereby avoiding cracking due to oxidative expansion. This excellent high temperature deformation resistance can be attributed to the formation of a refractory phase of Sc 2 Si 2 O 7 at the edge of fine particles. Fast breaking immunity test at room temperature and 1370 OC, Sc 2 O 3 -Si 3 N 4 The fast breaking strengths are 748 MPa and 496 MPa, respectively, which are much faster than the fast-breaking strength of other rare earth-densified silicon nitride. Moreover, the creep resistance of Sc 2 O 3 -Si 3 N 4 is larger than that of MgO-Si 3 N. 4 high one to two orders of magnitude. Sc 2 O 3 -Si 3 N 4 is oxidized in air at 1300 ° C for 100 hours with a weight of 0.1 mg / cm 3 , only under the same conditions Y 2 O 3 -Si 3 N 4 Half of it.钪SiAlON(β'-(Sc-Si-Al-ON)) ceramics also have good oxidation resistance.
1.3.3 ferroelectric ceramics can be used in the manufacture of scandium oxide based ceramic ferroelectric relaxor: lead scandium tantalate PbSc0.5Ta0.5O3 (PST), and lead scandium niobate PbSc0.5 Nb0.5O 3 (PSN). With a large electromechanical coupling index and a high dielectric constant, PSN is a promising material for converters. The PST exhibits an anti-thermoelectric effect under bias and can be used for heat detectors.
1.4 Electron and Electromagnetic Materials As an activator for oxide cathodes, it is used in electronic cathode tubes to greatly increase the thermal electron emission and improve the life of the cathode of the tube, thus adapting to the current high-definition, high-brightness of the picture tube, display tube and projection tube. The need for large-scale development. Japan's Mitsubishi, Toshiba, Hitachi, Matsushita and other companies are actually developing new color picture tube cathodes. This new type of cathode coated with ruthenium has a service life of up to 30,000 hours, which is three times that of a general cathode. The picture is bright, the definition is high, and the image is more vivid.
Sc 2 Se 3 and Sc 2 Te 3 are semiconductor materials; Sc 2 S 3 can be used as thermistor and thermoelectric generator; ScB 6 can be used as the cathode of the electron tube; and Sc 2 O 3 single crystal is used for the manufacture of the instrument. Bismuth sulfite has a high melting point and low evaporation pressure in air. It has attracted great interest in semiconductor applications. Replacing partial iron oxide in ferrite with cerium oxide can increase the coercive force. Improved performance of computer memory components. A small amount of rhodium added to the yttrium iron garnet improves magnetic properties.é’ªReplaces iron to increase its magnetic distance and magnetic permeability, and lowers the Curie temperature, which is beneficial for microwave technology. Niobium and rare earth elements can be used to make high quality iron-based permanent magnet materials. Sc-Ba-Cu-O is a superconducting material with an experimental critical temperature of 98K.
1.5 Energy and radiochemistry Metals have good thermal stability and strong fluorine absorption properties, and have become an indispensable material for the atomic energy industry. Fluoride targets made of bracts are installed in the accelerator for various nuclear physics experiments; high-energy neutrons are produced in neutron generators, and are neutron sources for activation analysis, geological prospecting, etc. Since the radius of the helium atom is similar to that of helium, it can be used as a stabilizer for the δ phase. Adding a small amount of Sc 2 O 3 to the high-temperature reactor UO2 nuclear fuel can prevent UO2 from becoming U3O8, causing lattice transformation, volume increase and cracking. The radioactive isotope Sc46 can be used as a gamma ray source and a tracer atom for various aspects of scientific research and production, and it is used medically to treat deep malignant carcinoma. Germanium telluride (ScD 3 ) and telluride (ScT 3 ) are used in uranium ore detector elements. In metal-insulator-semiconductor silicon photovoltaic cells and solar cells, germanium is the best barrier metal with an efficiency of 10-15%. Adding Sc 2 O 3 to the AgO cathode of AgO alkaline storage can prevent AgO in high-temperature storage. Explain oxygen and improve battery efficiency.
1.6 Catalyst The petroleum industry is one of the most widely used sectors in the industry. The Sc 2 O 3 -containing Pt-Al catalyst is used for hydrogenation of heavy oil to refine petroleum. Sc 2 O 3 can be used for dehydration and deoxidation of ethanol or isopropanol, decomposition of acetic acid, production of ethylene from CO and H2, production of chlorine from waste hydrochloric acid, and oxidation of CO and N 2 O. The activated alumina is impregnated with ZrO(NO 3 ) 2 , Sc(NO 3 ) 3 , H 2 PtCl 6 and RhCl 3 and calcined to obtain a catalyst, which can be used for purifying high-temperature exhaust gas such as automobile exhaust gas. When cumene is cracked, the activity of the ScY zeolite catalyst is 1000 times greater than that of the aluminum silicate.
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