Calcium boride

Molecular formula: CaB6

CAS number: 12007-99-7

Properties: black gray powder

Density: 2.33g/cm3

Melting point: 2230℃

Calcium hexaboride (also known as calcium boride) is a compound of calcium and boron with the formula CaB6. With excellent electrical conductivity, high hardness, chemical stability and high melting point, it is a gray-black solid, glossy, inactive powder with low density. It has a cubic structure typical of metal borides, consisting of an octahedral unit of six boron atoms bound to calcium atoms. Both CaB6 and lanthanum-doped CaB6 exhibit weak ferromagnetism, No.:12007-99-7, and a microhardness of 27GPa. The relative density is 2.33, the melting point is 2200℃, the Knoo hardness is 2600kg/mm2, the Young modulus is 379GPa, and the resistivity of the pure crystal is greater than 2·10 10ω ·m. CaB6 is a semiconductor with an energy gap of about 1.0 electron volts. It is stable at high temperature in the air, insoluble in hydrochloric acid, dilute sulfuric acid, does not react with water, can be eroded by strong oxidants such as chlorine, fluorine, nitric acid, hydrogen peroxide, and alkali reaction is slow.

Application: Used as a boron-containing additive for oxidation resistance, corrosion resistance and thermal strength improvement of dolomite carbon and magnesium dolomite carbon refractories. Used as a deoxidizing degassing agent for high conductive copper to improve conductivity and strength. A new type of material for neutron protection in nuclear industry. Used as a new semiconductor material in spintronic components with a residence temperature of 900K. Used as a raw material for the manufacture of boron trichloride (BC13) and amorphous boron. It is used as raw material for manufacturing high purity metal borides (TiB2, ZrB2, HfB2, etc.) and high purity boron alloys (Ni-B, Co-B, Cu-B, etc.). Used for desulfurization, oxygen removal and boron increase of alloy cast iron
Pills. It is used as a desulfurizing, deoxidizing and boronizing agent for boron steel and a deoxidizing agent for metal melting.

Structure information: The crystal structure of calcium hexaboride is a cubic lattice, the center of the cell is calcium, and the vertices are a three-dimensional boron network formed by tight regular boron atoms octahedron connected by boron-boron bonds. Each calcium has 24 next-door boron atoms. The calcium atoms are arranged in a simple cube stack, so there are holes between the eight calcium atoms located at the apex of the cube. Extending the simple cubic structure by introducing the octahedral B6 group, which is filled with calcium and hexaboride groups, another way to describe calcium hexaboride is the CSCL-type structure with the metal B6 2-octahedral polyanion, with the calcium atoms occupying the Cs site and the B6 octahedron at the Cl site. The length of the Ca-B bond is 3.05 A, and the length of the BB bond is 1.7 A.
The nuclear magnetic resonance NMR data for 43Ca contains a delta peak of -56.0ppm and a delta difference at -41.3ppm, where the maximum peak width of the delta difference is 0.85, and the negative shift is due to the high coordination number.
Raman data: Due to the activity patterns of A1g, Eg, and T2g, calcium boride has three Raman peaks at 754.3, 1121.8, and 1246.9cm-1.
Properties: CaB6 has been studied for its special physical properties such as superconductivity, valence state fluctuations, and the Kondo effect. However, the most remarkable property of CaB6 is its ferromagnetism. It appears unexpectedly at high temperatures (600 K) and low magnetic moments. The source of this high temperature ferromagnetism is the connection of the ferromagnetic phase of the diluted electron gas with a putative exciton state in calcium boride or an external impurity on the sample surface. Impurities may include iron and nickel and may come from the boron used to prepare the sample.
Preparation method: Calcium oxide and boron powder are evenly mixed and dried, and put into a high-temperature reactor; The high temperature reactor should be vacuumed before heating treatment. Calcium oxide and boron powder react at high temperature under vacuum and inert gas protection. The calcium hexaboride ceramic powder was separated and purified. The calcium hexaboride ceramic powders were separated and purified by ball milling to obtain uniformly dispersed calcium hexaboride ceramic powders. The method of the invention is simple, easy to realize, low manufacturing cost, and the prepared calcium hexaboride ceramic powder has small particle size and uniform dispersion.
Typical application products:
◆ Used as a boron-containing additive for oxidation resistance, corrosion resistance and thermal strength improvement of dolomite carbon and magnesium dolomite carbon refractorics. CaB6 can improve the strength and bulk density of castable after treatment at various temperature segments
CaB6 can promote the high temperature densification degree of castable, so that castable can obtain better oxidation resistance and higher high temperature bending strength and erosion resistance. CaB6 can obviously improve the various properties of iron hook castable. When 0.5% calcium boride is added, the castable has better comprehensive properties.
◆ Used as a deoxidizing degassing agent for high conductive copper to improve conductivity and strength.
◆ Used as a new material for neutron protection in nuclear industry.
◆ Used as a new semiconductor material in spintronic components with a residence temperature of 900K. CaB6 has excellent electrical conductivity and low work function, so it can be used as a hot cathode material.
◆ Used as raw material for the manufacture of boron trichloride (BCl3) and amorphous boron.
◆ Used as raw material for manufacturing high-purity metal borides (TiB2, ZrB2, HfB2, etc.) and high-purity boron alloys (Ni-B, Co-B, Cu-B, etc.). CaB6 is used as raw material to prepare other borides, such as hexagonal boron nitride, superconducting MgB2, etc.
◆ Used as a mixture containing catalyst calcium - boron nitride (Ca3B2N4) and hexagonal boron nitride, with its production of excellent crystal cubic boron nitride.
◆ Used as a desulfurizing, deoxidizing and boronizing agent for boron alloy cast iron.
◆ Used as a desulfurizing, deoxidizing and boronizing agent for boron steel.
◆ Used as a deoxidizer for metal melting, The results of comparative test show that the deoxidation capacity of calcium hexaboride deoxidizer is higher than that of copper boron alloy and phosphorus copper, and it has a purification effect on copper liquid, has a strengthening effect on copper matrix, and has no pollution to copper liquid. When the amount of calcium hexaboride is >0.60%, the oxygen content of copper liquid can be reduced to <20×10-6, reaching the domestic standard of oxygen-free copper. The effect of calcium hexaboride on the conductivity of copper is very small, and the relative conductivity of copper is in the range of 88% ~ 91.6% in the range of calcium hexaboride addition (0.69% ~ 1.12%). With the addition of calcium hexaboride, the tensile strength of copper continues to increase, the elongation rises first and then decreases, and reaches the maximum value when the addition of calcium hexaboride is 0.88%.
◆ Micro powder and additives for engineering ceramics
CaB6 as a special ceramic and special ceramic additive application: CaB6 can be used as an additive for the sintering process of some borides and carbide ceramics, on the one hand, it can improve the physical and chemical properties of ceramics. For example, superfine TiB2 is used as the matrix, CaB6 is added as the second phase, and after hot pressing, the growth of grains is prevented due to the dissolution of Ca, so that such materials have extremely high microhardness and bending strength. Calcium hexaboride has very high melting point, hardness, strength, chemical stability, good electromagnetic properties and strong neutron absorption ability, so that it has been used in refractory and wear-resistant materials, composite materials, ceramic materials, semiconductor materials and nuclear control materials. Coating additive and aluminum magnesium alloy with CaB6.
◆ Calcium boride is used in the manufacture of boron alloy steel and the production of oxygen-free copper as a deoxidation agent. The latter results in higher electrical conductivity than conventional phosphorus deoxidized copper due to the low solubility of boron in copper. CaB6 can also be used as high temperature materials, surface protection, abrasives, tools and wear resistant materials.
CaB6 is also a promising candidate for type n thermoelectric materials because its power factor is not less than that of common thermoelectric materials Bi2Te3 and PbTe.
Caution: Calcium boride is irritating to the eyes, skin and respiratory system. Use appropriate protective glasses and clothing when handling this product. Never pour calcium boride into a drain or add water to it.