Boron Phosphate

Boron Phosphate

Boron phosphate has the chemical formula BPO4 and is an inorganic compound. The reaction of phosphoric acid and boric acid is the most basic method of producing it. It is a white infusible solid that evaporates at temperatures above 1450 °C.

Boron phosphate is chemically stable and resistant to acids and alkalis, which makes it useful as a protective coating material in corrosive environments. It is a hard and brittle material with a high compressive strength. It also has a low coefficient of thermal expansion, which makes it useful in high-temperature applications where thermal cycling is required.


  • Physical properties: It is a white crystalline solid with a density of 2.54 g/cm³. It is insoluble in water and most organic solvents, but can be dissolved in concentrated acids.
  • Thermal stability: It has excellent thermal stability, with a melting point of 950°C and a decomposition temperature of around 1100°C. This makes it useful for high-temperature applications.
  • Electrical properties: It is an electrical insulator with a low dielectric constant, which makes it useful for applications where electrical insulation is required.
  • Optical properties: It is a transparent material with a refractive index of 1.5, which makes it useful as an optical material for lenses and prisms.


Boron phosphate can be synthesized by a variety of methods, including solid-state reactions, sol-gel methods, and hydrothermal synthesis. Its properties and applications make it a promising material for various technological and industrial applications.

Boron phosphate is synthesized from phosphoric acid and boric acid at a temperature range from 80 °C to 1200 °C. The relatively cold treatment produces a white amorphous powder, which is converted to a microcrystalline product when heated at about 1000 °C for 2 hours.

The main reaction of the process is:

H3BO3 + H3PO4 → BPO4 + 3 H2O

New ways of synthesizing the compound have also been reported, such as hydrothermal and microwave synthesis.


If obtained at pressure, the ordinary structure is isomorphous with the β-cristobalite, while subjecting it to high pressure is obtained a compound isomorphic with α-quartz. The structure of AlPO4, berlinite, is isomorphous with α-quartz.


Boron phosphate is used in various applications, including as a catalyst in organic reactions, in the production of ceramics, and as an electrode material in lithium-ion batteries. It also has potential applications in the nuclear industry, as it can absorb neutrons and has a low thermal neutron capture cross-section. It is used as a catalyst for dehydration and other reactions in organic synthesis. Also, it serves as a source of phosphates for exchange reactions in the solid state to obtain metal phosphates.