Copper Oxides

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.

References in periodicals archive ?
Over the years, using fatty acids to concentrate copper oxides lost popularity, with most operations preferring the controlled potential sulphidisazition (CPS) method.
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.
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.
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.
They quickly realized that in these materials, lattice vibrations alone aren't strong enough to maintain such pairing at the high superconducting transition temperatures observed in the copper oxides.
But copper oxides are not the only superconductors worthy of study.