Bismuth(III) sulfide

Bismuth(III) sulfide, also known as bismuth trisulfide, is a chemical compound with the formula Bi₂S₃. It is a brownish-black solid that occurs naturally as the mineral bismuthinite.

Structure and Properties

Bismuth(III) sulfide is composed of bismuth and sulfur atoms in a 2:3 ratio. The compound crystallizes in an orthorhombic structure, which is characterized by its layered arrangement. Each bismuth atom is surrounded by sulfur atoms, forming a distorted octahedral geometry.

The compound is known for its high density of 6.78 g/cm³ and its relatively high melting point of 685 °C. Bismuth(III) sulfide is insoluble in water, which makes it stable under normal environmental conditions.

Occurrence

Bismuth(III) sulfide occurs naturally as the mineral bismuthinite, which is an important ore of bismuth. Bismuthinite is typically found in hydrothermal veins and is often associated with other sulfide minerals such as galena and chalcopyrite.

Applications

Bismuth(III) sulfide is used in various applications due to its semiconducting properties. It is used in the manufacture of thermoelectric materials, which are capable of converting temperature differences into electrical voltage. Additionally, Bi₂S₃ is used in the production of infrared sensors and other electronic devices.

Synthesis

Bismuth(III) sulfide can be synthesized through several methods, including the direct combination of elemental bismuth and sulfur at high temperatures. Another common method involves the precipitation of bismuth(III) ions with sulfide ions in an aqueous solution.

Safety and Handling

While bismuth(III) sulfide is generally considered to be of low toxicity, it should be handled with care to avoid inhalation or ingestion. Proper protective equipment, such as gloves and masks, should be used when handling the compound.

Also see

• Bismuthinite
• Bismuth
• Sulfide minerals
• Thermoelectric materials