Cuprate oxide

Cuprammonium rayon, 11 263—265 Cuprate oxides, 23 838-839 Cuprate superconductors, 23 837 Cupric bromide, physical properties of,... 

Below is a brief review of the published calculations of yttrium ceramics based on the ECM approach. In studies by Goodman et al. [20] and Kaplan et al. [25,26], the embedded quantum clusters, representing the YBa2Cu307 x ceramics (with different x), were calculated by the discrete variation method in the local density approximation (EDA). Although in these studies many interesting results were obtained, it is necessary to keep in mind that the EDA approach has a restricted applicability to cuprate oxides, e.g. it does not describe correctly the magnetic properties [41] and gives an inadequate description of anisotropic effects [42,43]. Therefore, comparative ab initio calculations in the frame of the Hartree-Fock approximation are desirable. 

Soluble and volatile alkoxides of copper are precursors in sol-gel-like routes to cuprate-oxide superconductors1 and in the CVD of copper and copper oxides,2 respectively. Copper(II) alkoxides are typically prepared by alcohol-interchange reactions with dimethoxycopper(II) however, most are insoluble... 

A new approach to the theory of high-7 superconductivity in cuprate oxides is proposed, based on the possibility of superelectrons derived from inner closed shells in shrunken atoms induced h 2 strong screened attractive interaction between an electron and an ion. An electrostatic fluctuation connected with an electronic polarizability halts the breaking-up of the pre-existing pairs of electrons with antjparalle) spins in the shells. The transport of superelectrons can be explained by the virtual tunneling. 

Key words metal insulator transition superconductivity HTS cuprates oxides disordered metals. 

Conversion of cuprate oxide thin films into superconductors... 

One of the representative applications of the superconductors based on cuprate oxides is their use as a component of the NO sensor. 

There have been some attempts to apply the cuprate oxide superconductors to chemical sensing. When gases such as NO, NO2, N2O exist in the ambient atmosphere, the resistivities of YBa2Cu307 j, and Eui+ ,Ba2-xCu307 j, increase remarkably (Munakata... 

Copper(l) oxide, CujO. Red solid formed from Cu(II) salt and hydrazine or heat on CuO. Gives a cheap red glass and a cuprate, KCuO (K2O plus CU2O). 

Copper(II) oxide, CuO. Black solid formed by heating Cu(OH)2, Cu(N03)2, etc. Dissolves in acid to Cu(II) salts, decomposes to CU2O at 800 C. Forms cuprates in solid state reactions. A cuprate(III), KCUO2, is also known. 

It is readily dehydrated on warming, to give the black oxide CuO. It dissolves in excess of concentrated alkali to form blue hydroxo-cuprate(II) ions, of variable composition it is therefore slightly amphoteric. If aqueous ammonia is used to precipitate the hydroxide, the latter dissolves in excess ammonia to give the deep blue ammino complexes, for example [Cu(NH3)4(H20)2] ... 

The thermodynamics of the 123 compound have been extensively studied and writing dre formula as (YBa2Cu3)Oj. it has been shown that at 1000 K the value of z changes from 6 to 6.6 in dre oxygen pressure range 10 " to one atmosphere of oxygen. Above this temperature, the 123 compound decomposes to 211 plus barium cuprate and cuprous oxide according to the reaction... 

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