Copper Oxides

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Copper Oxides

 

compounds of copper and oxygen: copper (I) oxide Cu2O; copper (II) oxide, CuO; copper (III) oxide, Cu2O3; and copper peroxide, CuO2. Copper (III) oxide Cu2O3 is unstable.

Copper (II) oxide, or cupric oxide, CuO, occurs in nature as the black mineral tenorite (melaconite). It is unstable and begins to decompose at 800°C; it is readily soluble in cyanide solutions and in acids (the latter is used in copper hydrometallurgy).

Cupric hydroxide, Cu(OH)2, is precipitated out in the form of blue particles upon the interaction of copper (II) salts with alkalis in solutions. Freshly precipitated Cu(OH)2 is soluble in alkalis; however, its acidic nature is hardly evident. Its corresponding salts (for example, Na2CuO2) are called cuprites. In hydrous ammonia, cupric hydroxide forms a blue solution, [Cu(NH3)4](OH)2; this solution is known to dissolve cellulose. Upon dilution or acidification, the cellulose once more precipitates out. This process is used in the manufacture of rayon.

Copper (II) oxide serves as a green dye and a blue dye in the glass-making and enamel industries; it is also used in the manufacture of ruby glass.

Copper (I) oxide, or cuprous oxide, Cu2O, forms the brownish red mineral cuprite. It melts at 1230°C without decomposing and is readily reduced to metal form by the action of hydrogen and carbon monoxide. Cu2O dissolves completely in dilute sulfuric acid only in the presence of oxygen; in concentrated H2SO4 it dissolves with the formation of SO2. Cu2O is obtained by roasting copper in an insufficient quantity of air. It is used in tinting glass and enamel; it is also used as a pesticide.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Copper oxides, including CuO and [Cu.sub.2]O, are p-type semiconductors because of presence of acceptors levels attributed to copper vacancies.
Scientists have been trying to figure out how high-temperature superconductivity works since copper oxides, or cuprates, were found to exhibit resistance-free flow in 1986.
The way electrons leak between the two copper oxides spontaneously creates a superconducting layer somewhere within the stack, able to operate at the relatively high temperature of 32 kelvin (-241 degrees C) - most superconductors work at even lower temperatures.
For example greens were achieved with chrome and copper oxides, blues with cobalt oxides, browns and rusty reds with iron oxides, browns and tans with manganese, nickel and rutile, blacks with saturated copper and manganese oxides and yellows with vanadium pentoxide.
The gloves are made of advanced copper oxides that are combined with special yarns and fibers, according to officials, who contend this new product represents a step forward in the field.
The scientists of the National Institute for Materials Science in Tsukuba, Ibaraki Prefecture discovered the compound by oxidizing sodium cobalt dioxide at a temperature of minus 268 C and found it had marked resemblance in superconducting properties with copper oxides.
in this figure, spherical copper oxides appear as elongated vertical streaks due to the combination of an elongated vertical (depth) scale and different sputtering rat es between the oxide and the metal wire.
Tarascon, "Particle size effects on the electrochemical performance of copper oxides toward lithium," Journal of the
That unexpectedly steep jump may point the way to similar boosts among sister copper oxides, says the study's leader, Jean-Pierre Locquet of IBM's Zurich Research Laboratory in Ruschlikon, Switzerland.