Thermodynamic characterization of high-temperature superconductors in the yttrium-barium-copper-oxygen system. The Y123 solid solution (Technical Report)

Abstract

Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation intoThermodynamic characterization of high-temperature superconductors in the yttrium-barium-copper-oxygen system. The Y123 solid solution Abstract: The aim of this report is to inform the chemical community about a selfconsistent thermodynamic data set for the YBa 2 Cu 3 O 6+z (1 ≥ z ≥ 0) solid solution, that is well known as the Y123 phase and possesses superconducting properties at z~1 and low temperatures. About 3300 experimental points obtained in 240 miscellaneous experiments published in 78 papers have been processed simultaneously in order to obtain the most reliable Gibbs energy function of the Y123 phase in the temperature range from 250 to 1300 K and pressures up to 100 kbar. A function is recommended for approximation of the Gibbs energy, which has 16 adjustable parameters. All other thermodynamic properties of the Y123 solution, including the conditions for its internal stability, can be derived from the assessed Gibbs energy. Brief descriptions of the thermodynamic model, experimental and data assessment methods as well as examples of self-consistent thermodynamic data applications are given.

Universal Method for Approximating the Standard Thermodynamic Functions of Solids

“…These parameters are correlated ones, so an adequate description of the functions may require a precision of presenting the numerical parameters, significantly higher than the estimated accuracy of their calculation. While approximating the experimental data, the model allows one to evaluate in addition to random errors also the possible systematic errors. , But it is necessary for this to have data on measurements of the C P ( T ) function at the same temperatures carried out in several different laboratories. But usually there is not enough data to correctly estimate the reproducibility variance of experiments even in the same laboratory as it is not customary to measure the heat capacity of the same substance at the same conditions several times by adiabatic calorimetry.…”

Ab Initio Thermochemistry of Solid‐State Materials

“…Yet even when we focus on fundamental thermochemical information, such as the Gibbs energy for the formation of orthorhombic YBa 2 Cu 3 O 6.5 , the strengths of the theory are already impressively demonstrated. For example, the free reaction enthalpy of this and similar phases have been measured most carefully, and the recent IUPAC report [147] contains an empirical Gibbs function for this compound with a total of 16 (!) parameters, in which a total of 3300 (!)…”

Ab‐initio‐Thermochemie fester Stoffe

“…Aber selbst wenn es um grundlegende thermochemische Angaben wie beispielsweise die Gibbs‐Energie der Bildung von orthorhombischem YBa 2 Cu 3 O 6.5 geht, läßt sich die Stärke der Theorie schon jetzt eindrucksvoll belegen. Beispielsweise wurde die freie Reaktionsenthalpie dieser und verwandter Phasen aufs sorgfältigste vermessen, und der kürzliche IUPAC‐Bericht147 enthält für diese Verbindung eine empirische Gibbs‐Funktion mit insgesamt 16 (!) Parametern, die an insgesamt 3300 (!)…”