How is calcium hexaboride CaB6 powder produced?

Overview of calcium hexaboride CaB6 powder

Calcium boride is a compound of calcium and boron, with the chemical formula CaB6. Because of its high conductivity, hardness, chemical stability and melting point, it is an important material. It is a black, shiny, chemically inert, low-density powder. It has a typical cubic structure of six metal borides, and has an octahedral unit of six boron atoms and calcium atoms.

In the past, due to various special physical properties (such as superconductivity, valence fluctuation and Kondo effect), people have studied CaB6. However, the most notable feature of CaB6 is its ferromagnetism. It occurs at an unexpectedly high temperature (600K) and magnetic moment at low temperatures. The origin of high-temperature ferromagnetism is the ferromagnetic phase of dilute electron gas, which is related to the assumed exciton state in calcium boride or external impurities on the sample surface. Impurities may include iron and nickel, and they may come from impurities in the boron used to prepare the sample.

CaB6 is insoluble in H2O, MeOH (methanol) and EtOH (ethanol), and dissolves slowly in acid. Its microhardness is 27 GPa, Knoop hardness is 2600 kg/mm2), Young's modulus is 379 GPa, and pure crystal resistivity is greater than 2.1010Ω·m. CaB6 is a semiconductor with an estimated energy gap of 1.0 eV. The low semi-metal conductivity of many CaB6 samples can be explained by accidental doping caused by impurities and possible non-stoichiometry.

The composite material of porous calcium borate and metal current collector is used as the cathode, and the insoluble conductive material is used as the anode. The electrolysis is carried out in a molten salt electrolyzer at 500-750°C. The molten salt electrolyte used contains the halide corresponding to the metal, which can be chemically reduced Calcium borate. The voltage applied by electrolysis is sufficient to reduce calcium borate, but not enough to decompose the molten salt electrolyte. The reduction product on the cathode is taken out from the electrolytic tank, washed with water, acid washed to remove impurities, and dried to obtain the product.

Calcium boride has the characteristics of high melting point and high hardness. Its physical and chemical properties are quite stable. When calcined in air, sub-micron CaB6 will only gain weight after 800 degrees Celsius, and it is not easy to oxidize. CaB6 is generally insoluble in hydrochloric acid and sulfuric acid. Technically, hot hydrochloric acid is used to remove impurities, but CaB6 is soluble in nitric acid.

How is calcium hexaboride CaB6 powder produced?

One of the main reactions of industrial production is:

CaO+3B2O3+10Mg→CaB6+10MgO

Other methods of producing CaB6 powder include:

Calcium or calcium oxide reacts directly with boron at 1000℃;

Ca + 6B→CaB6

Ca(OH)2 reacts with boron (carbothermic reduction) under vacuum at about 1700°C;

Ca（OH）2 + 7B→CaB6 + BO（g）+ H2O（g）

Calcium carbonate and boron carbide are in vacuum above 1400℃

Reaction (Carbothermal reduction) CaO and H3BO3 react with Mg to 1100°C.

Low temperature (500°C) synthesis

CaCl2 + 6NaBH4→CaB6 + 2NaCl + 12H2 + 4Na

Therefore, the material is relatively poor.

For example, in order to produce a pure CaB6 single crystal used as a cathode material, the CaB6 powder thus obtained is further recrystallized and purified by zone melting technology. The typical growth rate is 30 cm/h, and the crystal size is about 1x10 cm.

Single crystal CaB6 nanowires (diameter 15-40 nm, length 1-10 microns) can be obtained by pyrolyzing diborane (B2H6) on calcium oxide (CaO) powder at 860-900°C in the presence of Ni catalyst .

Application of calcium hexaboride CaB6 powder

1. It is used as a boron-containing additive for dolomite and magnesium dolomite refractories, which has the functions of anti-oxidation, anti-corrosion and improving thermal strength.

2. Used as a deoxidizing and degassing agent for highly conductive copper to improve conductivity and strength.

3. Used as a new material to prevent neutrons in the nuclear industry.

4. Used as a new type of semiconductor material in spintronic components at 900K.

5. Used as a raw material for the manufacture of boron trichloride (BCl3) and amorphous boron.

6. Used as a raw material for manufacturing high-purity metal borides (TiB2, ZrB2, HfB2, etc.) and high-purity boron alloys (Ni-B, Co-B, Cu-B, etc.).

7. It is used to manufacture a mixture of calcium boron nitride (Ca3B2N4) and hexagonal boron nitride containing catalyst to produce cubic boron nitride with excellent performance.

Calcium hexaboride CaB6 powder price

The price of calcium hexaboride varies randomly with the production cost of calcium hexaboride powder, transportation cost, international situation, exchange rate and market demand and supply. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for calcium hexaboride CaB6 powder, please feel free to contact us to get the latest price of calcium hexaboride CaB6 powder.

Calcium hexaboride CaB6 powder supplier

As a global supplier of calcium hexaboride CaB6 powder, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (including oxides, carbides, nitrides, single metals, etc.) high-purity targets, functional ceramics and structural devices, and provides OEM services.