Barium cuprate

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... 

Essentially single-phase 2223 (Tc = 125 K with zero resistance at 122 K) was obtained by heating stoichiometric quantities of the reactants at 890°C for 1 h (6X56) if this mixture was heated for more than 2 h or at temperatures above 900°C, a mixture resulted with 2212 as the major phase and 2223 as a minor component (56). The authors note that the temperature range in which the thallium-based superconductors can be formed without decomposition to barium cuprate phases is very narrow (6). 

As the liquid is cooled further, more yttria-poor compounds are formed, such as barium cuprate (BC), that are difficult to... 

Rozental O.M., Fotiev V.A., Avvakumov E.G., Fedanchin E.l. Mechanosynthesis of yttrium and barium cuprates. Proc. All-Union Scientific and Technological Conference Mechanochemical synthesis , Vladivostok, 1990 112-14. 

Recently, HTSC properties were found for certain new complex cuprates of alkaline-earth and rare-earth metals [237,238]. Electrosynthesis of these compounds by analogy with the formation of barium cuprate films [228,229] appears to be possible. 

Lately high-temperature superconductors with rare-earth ions in their structure have been widely investigated. These compounds are based on antiferromagnetic dielectrics (yttrium-barium cuprates, cuprates of lanthanum or neodimium, etc.) having a distinctive lamellar structure which defines the peculiarities of magnetic interactions and magnetic ordering in the system of rare-earth ions. 

Standard Gibbs-eneigy fijnctions (A G" eq. 2) of formation of barium cuprates from oxides according to Voronin and Degterov (1994) units have been omitted... 

---