What is lanthanum boride? Application of lanthanum hexaboride.
Lanthanum hexaboride, referred to as lanthanum boride, molecular formula: LaB6, purple powder, insoluble in water, hydrochloric acid, very widely used, has been successfully used in radar aerospace, electronic industry, instrumentation, instruments, home appliances, metallurgy, environmental protection and other more than 20 military and high-tech fields. Its series products mainly include three kinds of powder, polycrystal, single crystal. In particular, lanthanum hexaboride single crystal is used to make high-power electron tube, magnetron, electron beam, ion beam and accelerator cathode materials.
Appearance and specifications of lanthanum hexaboride powder
Lanthanum hexaboride chemical formula: LaB6
Lanthanum hexaboride particle size: micron class/submicron class
Lanthanum hexaboride Color: Purple
Lanthanum hexaboride crystal type: cubic
Lanthanum hexaboride melting point: 2210 ℃
Purity of lanthanum hexaboride: >99.9%
Density of lanthanum hexaboride: 4.72 g/cm3
Emission constant of lanthanum hexaboride: 29A/CM2.K2
Lattice constant: 4.157A
Production method: Reduction method
Physical and chemical properties of lanthanum hexaboride
LaB6 is an inorganic nonmetallic compound composed of low-cost boron and rare metal lanthanum. It has special crystal structure and basic properties of borides. From the perspective of material characteristics, lanthanum hexaboride LaB6 is a refractory metal compound with a cubic crystal structure, featuring high hardness, high conductivity, high melting point, low thermal expansion coefficient and good chemical stability. At the same time, lanthanum hexaboride has high emission current density, low evaporation rate, strong ion bombardment resistance, strong electric field resistance and radiation resistance. It has been applied in cathode materials, electron microscope, electron beam welding, discharge tube and other fields requiring large emission current.
LaB6 is chemically stable and does not react with water, oxygen or even hydrochloric acid. At room temperature, it only reacts with nitric acid and aqua regia; Under aerobic atmosphere, oxidation will occur at 600 ~ 700℃. In vacuum atmosphere, LaB6 material is easy to react with other substances or gases to form low melting point substances; At high temperature, the formed substance will continue to volatilize, exposing lanthanum hexaboride crystal to the emission surface of low escape power, and thus lanthanum hexaboride has excellent anti-poisoning ability.
LaB6 cathode has low evaporation rate and long service life at high temperature. When heated to a high temperature, the lanthanum atoms on the surface will generate vacancy due to evaporation loss, and the lanthanum atoms in the interior will also diffuse out to fill the vacancy accordingly, so that the boron frame structure remains unchanged. This property makes the evaporation loss of LaB6 cathode to a very low degree, while maintaining an active cathode surface. Under the same emission current density, the evaporation rate of LaB6 cathode materials at high temperature is lower than that of ordinary cathode materials, and the low evaporation rate is an important factor to prolong the service life of cathode.