Silver

Silver, a shiny, white precious metal, possesses a face-centered cubic crystal structure. It displays an extraordinarily broad range of positive physical characteristics, for example it is the best known reflector of visible light and has the highest thermal and electrical conductivity of all the metals. After gold, soft silver (HV 30) is the most ductile metal; it can be drawn into extremely fine wires and hammered into exceptionally thin sheets, or leaf. Further chemical properties: Silver is resistant to non-oxidizing acids such as hydrochloric acid at room temperature, but is slightly soluble in oxidizing acids (e.g., nitric acid), as well as heated, concentrated sulfuric acid or alkali cyanide solutions containing oxidizing agents. Silver is resistant to melting in alkali hydroxide. Silver usually bonds with an oxidation state of +1, but valences of +2, +3 und +4 are also possible. It also possesses antibacterial, fungicidal and antiseptic qualities.

Mexico, Peru and China are the world’s largest silver producers, each accounting for approximately 15% of output. Silver occurs as a pure metal and in pyritiferous ores such as argentite, but usually as a by-product of copper or lead refining. Silver ore is often dissolved in sodium cyanide exposed to air in a cyanidization process, yielding a complex silver cyanide salt. This salt is reduced with base zinc to produce raw silver, and then electrolytic refining is performed to achieve pure silver. Silver recycled from photographic applications continues to be a key secondary source, as do used industrial catalysts and the jewelry industry.

Although silver once played a large role mainly as currency and jewelry, its areas of application have broadened with technical progress in the industrial world. Heraeus provides the electronics and electrical industries with products containing silver in the form of contacts, conductive pastes and conductive adhesives. Uses in the chemical industry include catalysts for ethylene oxide production. Photo paper and film function is based on the decay of silver halogenides through exposure to light, while the optical industry uses silver in mirror production. It has countless other technical applications, including solder alloys, heat and light reflectors. Heraeus produces sputtering targets for applying thin reflective layers in the manufacture of low-emission window glass. New materials and coating processes are exploiting its antibacterial qualities by embedding nanoscale silver in products such as anti-microbial textiles. Silver continues to be widely used in dental technology (amalgam), as well as glass and enamel manufacturing.