Silver and Silver Alloys

Abstract

The workability, beauty, and bacteriocidal effects of silver have made it a most desirable metal since ancient times. The combination of desirable properties and the total resistance of silver to the formation of oxides has established its position as a critical metal for a myriad of advanced technology applications. Silver also imparts the properties to the many metals with which it forms commercially important alloys. Among its many important salts, the halides stand as unique photosensitive salts, providing the basis for high quality photography as well as for photochromic glass. More obscure properties of silver such as its high thermal reflectivity are also being fully exploited. For example, silver is used to provide energy‐saving domestic window glass. The unique interaction of silver and oxygen is being used to advantage in the superconductor industry. The superior fatigue resistance and lubricity of silver make it an essential component of high performance jet engines.

Sources of silver in the environment

“…The toxicity estimates for the metal are based almost entirely on the free ion [19,20], which is clearly not of environmental relevance. Some of the compounds that are relevant, silver sulfide, for example, are of very low solubility [4][5][6] and so are essentially not available. While a number of silver compounds do not have a great deal of data that relate to their toxicity or lack thereof, most recent studies conclude that they are orders of magnitude less toxic than silver ions [2,3].…”

“…Silver occurs as a minor constituent of the earth's crust, with an average of approximately 0.1 mg/kg [4,5,7] and is found throughout the world. The estimated primary supply (the amount that is actively mined) worldwide in 1994 was 331.6 million troy ounces (M oz) or 10.3 ϫ 10 6 kg [9].…”

“…The toxicity of silver ranges through several orders of magnitude, depending on the silver species or compound as well as the medium in which it is found [1][2][3]. Silver is found in the environment in four oxidation states: 0, 1ϩ, 2ϩ, and 3ϩ, with 0 and 1ϩ being the most common, while 2ϩ and 3ϩ are seldom seen naturally in the environment [4]. Nearly all silver minerals are compounds of silver with sulfur, or the homologues (e.g., selenium and tellurium) and neighbors on the periodic chart (arsenic, antimony, and bismuth).…”

“…The monovalent ion is common in surface waters, as sulfide, bicarbonate, or sulfate salts or adsorbed onto organic or inorganic materials. Silver may also be found as a part of more complex ions with chlorides and sulfates [4,6]. Many of these forms are not soluble or are only sparingly soluble, and, as a result, their availability to biological organisms is not great.…”