Barium Oxide: Properties, Processing, and Applications

Barium is found in ores, mostly in the form of barite (BaSO4) as it does not occur naturally as a free element. Barium makes up 0.05% of the earth’s crust. It is a member of the alkaline earth metals and it has a pale yellow and shiny appearance. Barium was discovered in 1772 by Carl Wilhelm Scheele when he showed that barium oxide was distinct from calcium oxide, a compound it was often mistaken for. Barium was first isolated in 1808 by Humphry Davy through an electrolysis method he devised [1].

Barium oxide, also known as baria, barium monoxide or oxobarium (IUPAC nomenclature), is a yellowish-white non-flammable material. It has the chemical formula BaO and it is also hygroscopic, which means it readily absorbs moisture from the air.

Barium, in the form of numerous other compounds, has many applications such as a drying agent in electronics, the paint industry, glassware and ceramic production, oil drilling, fireworks, and medicine, etc.

In this article, you will learn about:

  • The properties of barium oxide
  • The production and processing of barium oxide
  • Applications of barium oxide
  • Examples of grades or standards of barium oxide

Properties of barium oxide

Given that barium oxide exists primarily in crystalline powder form, there is limited information available about its properties, especially mechanical. Furthermore, bulk property values are not commonly available. Some of its properties have been deduced via computation rather than through empirical methods. The most important properties are presented below.

Table 1. Properties of barium oxide [2][3].



Molecular weight

153.326 g/mol


5.72 g/cm3

Boiling point

~ 2,000 °C

Melting point

1,923 °C

Crystal structure


Solubility in water at 20°C

3.48 g/100ml

Magnetic susceptibility

-29.1x10−6 cm3/mol



Specific Gravity


Coefficient of Linear Expansion


Shear Modulus

38 GPa 

Bulk Modulus

68 GPa

Elastic Anisotropy


Poisson's Ratio


Refractive Index


Polycrystalline dielectric constant


Production and processing of barium oxide

Barium oxide can be produced by thermally decomposing barium carbonate, BaCO3 or barium nitrate, Ba(NO3)2. The reactions are as follows:

BaCO3 → BaO + CO2

2Ba(NO3)2 → 2BaO + 4NO2 + O2

It can also be produced by the reaction of pure barium with oxygen as shown below.

2Ba + O2 → 2BaO

Barium oxide has also been synthesized through the reaction between barium chloride, BaCl2, and ammonia, NH3 and precipitated with deionised water [2]. This is one of several possible methods of producing barium oxide that can only be carried out under controlled environments in a laboratory.

Commercially, the production of barium oxide through the calcination of barium carbonate poses problems of extraction. This is because it is often contaminated with excess carbon, which is usually added to prevent the barium oxide from becoming barium peroxide. The presence of excess carbon makes its mixture with barium oxide appear black. Removing this excess carbon simply by heating the mix is not feasible as that would cause a reaction with the barium oxide and regeneration of barium carbonate, essentially reversing the progress made [4].

Applications of barium oxide

Barium oxide can be directly or indirectly used for the following [5]:

  • To coat hot cathodes in electronic devices
  • As an alternative to lead oxide in the production of optical crown glass because of barium oxide’s high contribution to the refractive index of glass
  • As an ethoxylation catalyst in the reaction between alcohols and ethylene oxide
  • As an oxygen source through heat fluctuation
  • To oxidize barium peroxide
  • As a reducing agent
  • As an oxidizing agent
  • In isomer separation processes
  • To increase the flux density of permanent magnets
  • In fuels as a cleaning agent called lubricating oil detergents
  • As a desiccant for drying gases and solvents. It has an added advantage of not swelling with moisture without becoming wet and sticky. 

There are other barium composites that have a wide range of uses, especially as perovskites. Their ability to sustain a strong electric field without conducting electricity is useful in electronics. Barium titanate and barium strontium titanate are dielectric materials, insulators which are useful for ceramic capacitors. They are also piezoelectric materials that make them useful for both high sensitivity actuators and sensors. Other widely used barium-containing oxides include the high-temperature superconductor yttrium barium copper oxide, YBa2Cu2O7-x (or YBCO), its related rare-earth compounds and also barium zirconate and barium hafnate, used as pinning centres in high-temperature superconductors [6].

Examples of grades or standards of barium oxide

There are many different barium-containing oxides also containing other elements. They are often designed for use in specific applications, mostly in powdered form with particle sizes as small as 30 nm. Examples of such grades are listed below.

Barium yttrium zirconate nickel oxide composite (BZY15-Ni) Powder

Barium zirconium yttrium cerate nickel oxide composite (BCZY721-NiO60w) Powder

Barium strontium iron cobaltite (BSCF) Powder

Barium titanate (BTO) Powder

Barium cerium yttrium zirconate (BZCY811) Powder

Barium iron zirconium cobaltite (BCFZ) Powder

Barium zirconium yttrium cerate (BCZY721) Powder

Bismuth sodium barium titanate (BNT-6BT) Powder

Barium yttrium zirconate (BZY15) Powder

Barium zirconate (BZO) Powder


[1] "Barium," JRank Science Encyclopedia, [Online]. Available: [Accessed April 2, 2020].

[2] A. Z. Bazeera and M. I. Amrina, "Synthesis and Characterization of Barium Oxide Nanoparticles," IOSR Journal of Applied Physics (IOSR-JAP), e-ISSN: 2278-4861, pp. 76-80, Feb. 2017.

[3] A. Jain*, S.P. Ong*, G. Hautier, W. Chen, W.D. Richards, S. Dacek, S. Cholia, D. Gunter, D. Skinner, G. Ceder, K.A. Persson (*=equal contributions), "The Materials Project: A materials genome approach to accelerating materials innovation," APL Materials, 1(1), 011002. 2013. [Online]. Available: [Accessed April 2, 2020].

[4] H. W. Rahn, C. J. Sindlinger, “Preparation of Barium Oxide,” U.S. Patent 2 876 073, March 3, 1959.

[5] "Barium Oxide," ChemicalBook, 2017 [Online]. Available: [Accessed April 2, 2020].

[6] B. H. Stafford, M. Sieger, R. Ottolinger, A. Meledin, N. M. Strickland, S. C. Wimbush, G. Van Tendeloo, R. Hühne and L. Schultz, "Tilted BaHfO3 nanorod artificial pinning centres in REBCO films on inclined substrate deposited-MgO coated conductor templates," Supercond. Sci. Technol, vol. 30 (5), 055002, March 2017.