by Bismuth is a chemical element with the symbol Bi and atomic number 83. Commonly known as bismuth, it is a pewter-gray metal and one of the pnictogens, together with nitrogen, phosphorus, arsenic, and antimony. The free element is 86% as dense as lead. It occurs both naturally and as a refinery byproduct in the manufacture of uranium, cadmium and lead. In this article, we will discuss the properties, uses and Bismuth outlook of this unique element.
Physical and Chemical Properties
Bismuth has a number of unusual physical properties. It is a brittle metal with a very low melting point of 271.4 °C, higher than its fellow metalloids but lower than metals like iron and tin. Its unique crystal structure and layout causes it to have the lowest thermal conductivity of any metal, resulting in useful thermoelectric properties. The expansion of bismuth upon solidification is the highest of any element, leading to stress and fracturing in castings. These unusual physical characteristics have led to specific uses where bismuth’s properties are desired.
Bismuth also behaves differently from other metals chemically. It does not form amalgams with mercury or silver soldering alloys due to its similar electronegativity to oxygen. It does not tarnish in air, is not attacked by oxidizing acids like nitric acid, and has low toxicity. These unusual traits mean bismuth can be used for applications or products where toxicity, oxidation issues or leaching are of concern.
Historical Applications
Bismuth has a long history of being used in medicines due to its non-toxic qualities. Bismuth subsalicylate, commonly known by the brand name Pepto-Bismol, is still widely used today as an antacid and treatment for diarrhea and indigestion. Bismuth was also commonly used in traditional cosmetics, being added to face powder and used as an eyeshadow pigment due to its white coloring.
In the 19th century, bismuth enjoyed widespread use in metallurgy applications. It was used to refine uranium, lead, and tin by removal of impurities like silver, sulfur, and arsenic. The unique properties of bismuth also led to some specialized uses, such as making cooling blocks to regulate the temperature of glass furnaces and replacing tin in solders. However, industrial development reduced its role in such applications.
Bismuth’s Chemistry in Modern Applications
Despite reduced metallurgical applications, modern science continues to leverage bismuth’s unique chemistry. Pharmaceuticals remain a major industrial use. Bismuth compounds are an active component in many antidiarrheal medications and treatments for ulcers and stomach issues. Bismuth subsalicylate, the active ingredient in Pepto-Bismol, works by coating the lining of the stomach and intestines, easing diarrhea symptoms.
Leveraging its low toxicity, bismuth shot and bismuth alloys are used as replacements for lead in applications like fishing weights and ammunition where environmental impact is a concern. Bismuth oxides, nitrates, and carbonates are used as pigments in the cosmetics industry for coloring or opacifying products like makeup or nail polish. Bismuth vanadate specifically produces a silvery-white color.
The unique electron shell structure of bismuth permits specific applications utilizing its thermoelectric properties. Bismuth telluride is a semiconductor frequently used in Peltier coolers, which operate on the principle of heat absorption and rejection depending on electric current flow direction. This means Peltier devices can be used for heating or cooling in applications like wine cellars, laser equipment and even picnic coolers.
Future Developments
While bismuth sees use already, ongoing materials science research aims to develop new applications for this quirky metalloid. Its electron behavior makes bismuth promising for infrared detectors, as semiconducting bismuth-based materials can strongly absorb infrared wavelengths. Ongoing work studies bismuth in topological insulators, which conduct electricity only on their surface and may have applications in quantum computing and spintronics.
Alloys combining bismuth with other metallic elements are an area of research. Bismuth alloys could potentially replace toxic materials like lead in applications like bullets, fishing gear or plumbing without sacrificing density or hardness. Scientists also study bismuth telluride for thermoelectric energy generation, seeking ways to boost its efficiency to a level enabling waste heat recovery on an industrial scale.
Though often overlooked due to its lack of mainstream applications, bismuth displays fascinating and useful physical behaviors. Continuing materials science may uncover new functions for bismuth as technologies evolve and sustainability concerns drive replacement of toxic materials. The unique chemistry of this silvery-pink element positions it well for a variety of specialized future uses.
The global Bismuth is expected to witness steady growth over the next decade driven by increasing demand from metallurgy and electronics sectors. As discussed in the market research report published by Coherent Market Insights, bismuth consumption is projected to grow at a CAGR of over 3% through 2028 supported by growth in emerging applications like thermoelectric devices and pharmaceuticals. Asia Pacific currently dominates global bismuth production as well as consumption led by China while European and North American markets are also projected to expand. Key factors influencing the outlook include technological advancements, new product developments and capacity additions by major manufacturers globally.
