Bismuth is a brittle metal with a silvery-white, slightly pinkish luster: low melting point (about 271 degrees C), non-toxic, and dense. In recent years, driven by the global lead-free trend, it has become an important substitute for lead. Its main industrial use is in low-melting and fusible alloys - mixing bismuth with lead, tin, cadmium and indium can lower the melting point below 70 degrees C, widely used in fusible plugs of fire sprinklers, boiler safety interlocks, automatic fire extinguishing devices and over-temperature protection elements in electrical equipment, which melt and trigger action once the temperature rises. In soldering, lead-free solders and low-temperature solder pastes increasingly use bismuth-based alloys to replace traditional tin-lead solder, for electronics assembly, food machinery and artwork restoration, meeting environmental directives such as RoHS. In medicine, bismuth preparations have a long history: bismuth subsalicylate is a well-known stomach remedy and antidiarrheal ingredient, used to relieve gastric discomfort and in combination therapy for H. pylori, while bismuth subcarbonate is used to protect the gastric mucosa. In consumer goods, bismuth is also used in clock fuses, fireworks (bismuth compounds burn with an emerald-green flame) and, as a lead substitute, in fishing sinkers, shot and weights. Non-toxic, low-melting and easy to process, bismuth is moving from a minor by-product metal to a star of eco-friendly replacement materials.
Bismuth oxide (Bi2O3) is bismuth's main oxide, a yellow powder used to color and flux ceramics and glass, and as a raw material for electronic ceramics, varistors and certain solid electrolytes, and in chemicals as a catalyst and pigment. Bismuth sulfide (Bi2S3), i.e. bismuthinite, is the main ore of bismuth in nature, gray with metallic luster, and the principal feedstock for bismuth smelting; its semiconductor properties are also of interest in optoelectronic and thermoelectric materials research. Bismuth oxychloride (BiOCl) is a white, pearlescent plate-like crystal with a soft, pearl-like luster, widely used in premium cosmetics as pearl creams, nail polish, eye shadow and talcum powder, and as a pearlescent pigment in high-grade plastics and coatings - an important non-toxic pearl-white in the cosmetics industry. Bismuth subcarbonate (Bi2O2CO3) is one of the main active ingredients in stomach and gastrointestinal medicines, with astringent, mucosa-protective and bacteriostatic effects, used in over-the-counter treatments for gastritis, gastric ulcer and diarrhea. In addition, bismuth subsalicylate is a well-known antidiarrheal ingredient, and bismuth-tin oxides are also used in certain specialty glasses and electronic ceramics.
