Abstract
The 124 superconductor YBa2Cu4O8 was prepared from the oxalate precursor Y2(C2O4)3. ·4BaC2O4·8CuC2O4·xH2O at one atmosphere oxygen pressure. In O2 the precursor decomposes in one step at 300°C and more gradually (300°–600°C) in Ar. The stability of the superconductor is strongly dependent on the gas atmosphere: in O2 and in air there is no significant weight change as long as the temperature does not exceed 800°C, whereas in a 1% O2-99%N2 mixture decomposition starts at about 670°C with the formation of CuO and YBa2Cu3Ox withx<7. The reduction of YBa2Cu4O8 in a 5% H2-95% Ar mixture takes place in at least four major steps with formation of products such as Y2O3, BaO, Cu2O, Cu, BaY2O4 and Ba4Y2O7.
Zusammenfassung
Aus dem Oxalatpräkursor Y2(C2O4)34BaC2O48CuC2O4·xH2O wurde der 124 Supraleiter YBa2Cu4O8 hergestellt. In Sauerstoff zersetzt sich der Präkursor bei 300°C in einem Schritt, in Argon nach und nach (300°–600°C). Die Stabilität des Supraleiters hängt stark von der Atmosphärenzusammensetzung ab: in Sauerstoff und in Luft gibt es bis 800C keinen bemerkenswerten Gewichtsverdust, während in einem Gemisch aus 1% O2 und 99% N2 die Zersetzung bei etwa 670°C beignnt, wobei CuO und YBa2Cu3Ox mitx gebildet wird. Die Reduktion von YBa2Cu4O8 in einem 5%H2-95%Ar-Gemisch erfolgt in mindestens vier Hauptschritten, wobei Produkte wie Y2O3, BaO, Cu2O, Cu, BaY2O4 und Ba4Y2O7 gebildet werden.
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A. Vos, J, Mullens, J. Yperman, J. Vanhees, L. C. Van Poucke, T. Krekels, G. Van Tendeloo, F. Persijn, I. Van Driessche and S. Hoste, Superconductivity, Ed. Raveauet al., Technology Transfer Series I.I.T.T.-I.C.A.M.S., Paris 1991, p. 85.
A. Vos. R. Carleer, J. Mullens, J. Yperman, J. Vanhees and L. C. Van Poucke, Eur. J. Solid State Inorg. Chem. 28 (1991) 657.
P.K. Gallagher, H. M. O'Bryan and G. S. Grader, Thermochim. Acta, 137 (1989) 373.
H. Vlaeminck, D. Depla and S. Hoste, Proceedings ISTEC, Tokyo 1991, in press.
P. Podhájecky and F. P. Dousek, Physica C, 173 (1991) 99.
J.-H. Chloy, D. Y. Jung, S. J. Kim, Q. Won Choi and G. Demazeau, Physica C, 185–189 (1991) 763.
D. C. Harris and T. A. Hewston, J. Solid State Chem. 64 (1987) 182.
D. C. Harris, M. E. Hills and T. A. Hewston, J. Chem. Educ., 64 (1987) 847.
J. Yperman, A. De Backer, J. Mullens and L. C. Van Poucke, Book of Abstracts, ESEAC, Noordwijkerhout 1992, p. 123.
J. Mullens, R. Carleer, G. Reggers, J. Yperman, J. Vanhees and L. C. Van Poucke, Proceedings NATAS, Boston 1990, p. 155.
J. Mullens, R. Carleer, G. Reggers, M. Ruysen, J. Yperman and L. C. Van Poucke, Bull. Soc. Chim. Belges, 101 (1992) 267.
K. Leroy, J. Mullens, J. Yperman, J. Vanhees and L. C. Van Poucke, Thermochim. Acta, 136 (1988) 343.
J. Mullens, A. Vos, R. Carleer, J. Yperman and L. C. Van Poucke, Thermochim. Acta, 207 (1992) 337.
E. M. Vogel, G. W. Hull and J. M. Tarascon, Materials Letters, 6 (1988) 269.
D. C. Harris and T. A. Hewston, J. Solid State Chem., 69 (1987) 182.
R. J. Cava, B. Batlogg, R. B. van Dover, D. W. Murphy, S. Sunskine, T. Siegrist, J. P. Remeika, E. A. Rietman, S. Zahurak and G. P. Espinosa, Phys. Rev. Letters, 58 (1987) 1676.
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Mullens, J., Vos, A., De Backer, A. et al. The decomposition of the oxalate precursor and the stability and reduction of the YBa2Cu4O8 superconductor studied by TG coupled with FTIR and by XRD. Journal of Thermal Analysis 40, 303–311 (1993). https://doi.org/10.1007/BF02546580
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DOI: https://doi.org/10.1007/BF02546580