Barium sulfide is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the formula Ba S. BaS is the barium compound produced on the largest scale. It is an important precursor to other barium compounds including

barium carbonate Barium carbonate is the inorganic compound with the formula BaCO3. Like most alkaline earth metal carbonates, it is a white salt that is poorly soluble in water. It occurs as the mineral known as witherite. In a commercial sense, it is one of ...

and the pigment lithopone, ZnS/BaSO₄. Like other

chalcogenide : 220px, Cadmium sulfide, a prototypical metal chalcogenide, is used as a yellow pigment. A chalcogenide is a chemical compound consisting of at least one chalcogen anion and at least one more electropositive element. Although all group 16 elemen ...

s of the alkaline earth metals, BaS is a short

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

emitter for electronic displays. It is colorless, although like many sulfides, it is commonly obtained in impure colored forms.

Discovery

BaS was prepared by the Italian alchemist Vincenzo Cascariolo (also known as Vincentius or Vincentinus Casciarolus or Casciorolus, 1571–1624) via the thermo-chemical reduction of BaSO₄ (available as the mineral barite). It is currently manufactured by an improved version of Cascariolo's process using coke in place of flour and

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...

. This kind of conversion is called a carbothermic reaction: : and also: : The basic method remains in use today. BaS dissolves in water. These aqueous solutions, when treated with

sodium carbonate Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

, give a white solid of

, a source material for many commercial barium compounds. According to Harvey (1957),Harvey E. Newton (1957). A History of Luminescence: From the Earliest Times until 1900. Memoirs of the American Physical Society, Philadelphia, J. H. FURST Company, Baltimore, Maryland (USA), Vol. 44, Chapter 1, pp. 11-43. in 1603, Vincenzo Cascariolo used barite, found at the bottom of Mount Paterno near

Bologna Bologna ( , , ; ; ) is the capital and largest city of the Emilia-Romagna region in northern Italy. It is the List of cities in Italy, seventh most populous city in Italy, with about 400,000 inhabitants and 150 different nationalities. Its M ...

, in one of his non-fruitful attempts to produce

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

. After grinding and heating the mineral with charcoal under reducing conditions, he obtained a persistent luminescent material that soon came to be known as ''Lapis Boloniensis'', or Bolognian stone. The

phosphorescence Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluor ...

of the material obtained by Casciarolo made it a curiosity.

Preparation

A modern procedure proceeds from barium carbonate: : BaS crystallizes with the

NaCl structure Sodium chloride , commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral hali ...

, featuring octahedral Ba²⁺ and S²⁻ centres. The observed

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...

of barium sulfide is highly sensitive to impurities.

Safety

BaS is quite poisonous, as are related sulfides, such as CaS, which evolve toxic

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

upon contact with water. Barium itself is also toxic.

References

{{Sulfides Barium compounds Monosulfides Cubic minerals Phosphors and scintillators Rock salt crystal structure