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Stability of YBa2Cu3O7−y superconductor in water
Solid State Communications, Vol. 65, No. 5, pp. 373-374, 1988. Printed in Great Britain.
0038-1098/88 $3.00 + .00 Pergamon Journals Ltd.
STABILITY OF YBa2Cu307_y S U P E R C O N D U C T O R IN WATER J. Dominec, L. Smr6ka, P. Va~ek and S. Geurten* Institute of Physics, Czechoslovak Academy of Sciences, 180 40 Praha 8, Na Slovance 2, Czechoslovakia and O. Smr6kov~i, D. S~,korov~i and B. H~jek Institute of Chemical Technology, 166 28 Praha 6, Suchb~itarova 5, Czechoslovakia
(Received 6 October 1987 by M. Cardona) The deterioration of superconductive properties of the YBa2CuaO7_y system due to the reaction with water was investigated by measurements of resistivity and magnetic susceptibility. It was found that these superconductors are destroyed in few minutes by boiling water. At lower temperatures the hydrolysis reduces the volume of the superconductive phase, as seen from the susceptibility measurements, while the resistivity remains almost unchanged.
ONE OF THE I M P O R T A N T factors, which can tibility versus temperature curve showed a large dehinder or support the applications of new high- crease of the relative volume of the superconductive temperature oxide superconductors is their stability in phase already after one minute. Further heating in the environment. In spite of the importance of this boiling water destroyed the superconductivity and the matter little attention has been paid to the influence of semiconductor character of resistivity was obtained. Another set of experiments involved the isochwater on superconductive properties of this material. Recently there appeared reports on the reactivity ronal soaking of samples in water of varying temof the Y-Ba-Cu4~) system with water. The system was perature Tw (20 min on each temperature). The results studied by electron microprobe analysis or X-ray dif- are summarized in Table 1 and Fig. 1, Fig. 2. No fraction method [1-3]. The samples has been shown to decompose by the action of water. In this Communication we describe the results of our study of soaking Table 1. Superconductive properties of the resistivity of of Y - B a - C u - O oxide samples in re-distilled water. water-treated sample. Duration of each treatment 20 Our samples were prepared by the standard technol- minutes ogy [4]. The transition temperature T,. of the samples in the state as prepared has been determined from the T~,.(°C) R (mf~) 7'50 (K) To (K) AT (K) resistivity to be above 90 K. Changes of their super21 90.0 89.5 1.5 conductive properties were investigated by measure- a b 4-5 20 90.9 89.3 1.5 ment of resistivity and ac susceptibility. The resistivity c 15-16 20 90.6 89.3 1.7 was measured by the standard four probe method, the d 25-26.5 20 91.2 90.1 1.8 susceptibility by a low frequency ac SQUID suscepe 35-36 21 91.2 90.0 1.7 tometer. The temperature was determined by a cali91.0 89.4 1.8 brated Pt thermometer. First we performed the isoth- f 43.5~t5 19 g 50-53 19 91.0 89.6 1.4 ermal heating of the samples in boiling water. Alh 63-67 18 92.1 91.1 1.8 though the resistivity versus temperature curve did not i 83-87 3.85 × 106 no superconductivity change after one minute of the soaking and a longer found time was necessary to alter this behaviour, the suscep-
* Permanent address: Eindhoven University of Technology, Eindhoven, Netherlands. 373
T,, ... temperature of water; R . . . resistance at room temperature; Ts0...midpoint of the resistive transition; T0...zero resistance point; A T = T g 0 T~0... width of the transition.
374
H I G H T, S U P E R C O N D U C T O R S
Vol. 65, No. 5
IO0~
<, ?e,
50 =i - - - ~
/ I
~
I
i
ol &O
&
--
i
]
Li
. I .
[ i
o 40 80 120 160 200 240 280
T(K}
Fig. 1. Temperature dependence of the resistivity. Letters a-i are related to individual runs (soaking for 20min - - see Table 1.) The runs a - h are undistinguishable on this scale. change of superconductivity, as manifested by the resistivity measurements, was observed up to T,. ~ 80°C. Above this temperature the superconductivity disappeared. The susceptibility measurements have shown, that when the temperature of water is below 30°C there is no change of g - T curve, above this temperature the volume of the superconductive phase decreases and the width of the transition increases. The onset temperature Tonset remains unchanged. The water in which a sample was soaked at 100°C for an hour was analyzed to determine the amount of Y, Ba and Cu resolved. The atomic absorption analysis showed a presence of Ba and Cu atoms only, with a ratio Ba:Cu ~ 104:1. N o Y atoms have been detected within the resolution of our equipment. The sample itself got covered by a very-light grey surface layer and two new peaks appeared in its X-ray diffraction spectra confirming the appearance of a new phase.
60
80
100 T(K)
Fig. 2. Relative change of the volume of the superconducting phase during isochronal soaking, a - - as prepared, b - - 20min at 44 + I°C, c - - 20min at 51 ___ l°C, d I 2 0 m i n a t 6 6 + I°C.
Acknowledgements - - We would like to thank E. Pollert for the X-ray experiment. REFERENCES I.
2.
M.P.A. Viegers, H.A.M. van Hal, J.H.I. Hengst, C. Langereis, H.C.M. Smoorenburg, P.F. Bongers, W. Kadowaki, Y.K. H u a n g & A.A. Menovsky, European Materials Research Society Meeting, Strasbourg (1987) abstract. D.M. de Leeuw, C.A.H.A. Mutsaers, H.A.M. van Hal, C. Langereis, J.W.C. de Vries, A.W. Kolfschoten & P.H. Joosten, European Mat-
erials Research Society Meeting, Strasbourg, 3. 4.
(1987) abstract. I. Nakada, S. Sato, Y. Oda & T. Kohara, Jap. J. Appl. Phys. 26, L697-L698 (1987). O. Smr6kov~i, D. S2~korov~i, J. Dominec, K. Jurek & L. Smr6ka, Phys. Status Solidi (a) 103, K36 (1987).
0038-1098/88 $3.00 + .00 Pergamon Journals Ltd.
STABILITY OF YBa2Cu307_y S U P E R C O N D U C T O R IN WATER J. Dominec, L. Smr6ka, P. Va~ek and S. Geurten* Institute of Physics, Czechoslovak Academy of Sciences, 180 40 Praha 8, Na Slovance 2, Czechoslovakia and O. Smr6kov~i, D. S~,korov~i and B. H~jek Institute of Chemical Technology, 166 28 Praha 6, Suchb~itarova 5, Czechoslovakia
(Received 6 October 1987 by M. Cardona) The deterioration of superconductive properties of the YBa2CuaO7_y system due to the reaction with water was investigated by measurements of resistivity and magnetic susceptibility. It was found that these superconductors are destroyed in few minutes by boiling water. At lower temperatures the hydrolysis reduces the volume of the superconductive phase, as seen from the susceptibility measurements, while the resistivity remains almost unchanged.
ONE OF THE I M P O R T A N T factors, which can tibility versus temperature curve showed a large dehinder or support the applications of new high- crease of the relative volume of the superconductive temperature oxide superconductors is their stability in phase already after one minute. Further heating in the environment. In spite of the importance of this boiling water destroyed the superconductivity and the matter little attention has been paid to the influence of semiconductor character of resistivity was obtained. Another set of experiments involved the isochwater on superconductive properties of this material. Recently there appeared reports on the reactivity ronal soaking of samples in water of varying temof the Y-Ba-Cu4~) system with water. The system was perature Tw (20 min on each temperature). The results studied by electron microprobe analysis or X-ray dif- are summarized in Table 1 and Fig. 1, Fig. 2. No fraction method [1-3]. The samples has been shown to decompose by the action of water. In this Communication we describe the results of our study of soaking Table 1. Superconductive properties of the resistivity of of Y - B a - C u - O oxide samples in re-distilled water. water-treated sample. Duration of each treatment 20 Our samples were prepared by the standard technol- minutes ogy [4]. The transition temperature T,. of the samples in the state as prepared has been determined from the T~,.(°C) R (mf~) 7'50 (K) To (K) AT (K) resistivity to be above 90 K. Changes of their super21 90.0 89.5 1.5 conductive properties were investigated by measure- a b 4-5 20 90.9 89.3 1.5 ment of resistivity and ac susceptibility. The resistivity c 15-16 20 90.6 89.3 1.7 was measured by the standard four probe method, the d 25-26.5 20 91.2 90.1 1.8 susceptibility by a low frequency ac SQUID suscepe 35-36 21 91.2 90.0 1.7 tometer. The temperature was determined by a cali91.0 89.4 1.8 brated Pt thermometer. First we performed the isoth- f 43.5~t5 19 g 50-53 19 91.0 89.6 1.4 ermal heating of the samples in boiling water. Alh 63-67 18 92.1 91.1 1.8 though the resistivity versus temperature curve did not i 83-87 3.85 × 106 no superconductivity change after one minute of the soaking and a longer found time was necessary to alter this behaviour, the suscep-
* Permanent address: Eindhoven University of Technology, Eindhoven, Netherlands. 373
T,, ... temperature of water; R . . . resistance at room temperature; Ts0...midpoint of the resistive transition; T0...zero resistance point; A T = T g 0 T~0... width of the transition.
374
H I G H T, S U P E R C O N D U C T O R S
Vol. 65, No. 5
IO0~
<, ?e,
50 =i - - - ~
/ I
~
I
i
ol &O
&
--
i
]
Li
. I .
[ i
o 40 80 120 160 200 240 280
T(K}
Fig. 1. Temperature dependence of the resistivity. Letters a-i are related to individual runs (soaking for 20min - - see Table 1.) The runs a - h are undistinguishable on this scale. change of superconductivity, as manifested by the resistivity measurements, was observed up to T,. ~ 80°C. Above this temperature the superconductivity disappeared. The susceptibility measurements have shown, that when the temperature of water is below 30°C there is no change of g - T curve, above this temperature the volume of the superconductive phase decreases and the width of the transition increases. The onset temperature Tonset remains unchanged. The water in which a sample was soaked at 100°C for an hour was analyzed to determine the amount of Y, Ba and Cu resolved. The atomic absorption analysis showed a presence of Ba and Cu atoms only, with a ratio Ba:Cu ~ 104:1. N o Y atoms have been detected within the resolution of our equipment. The sample itself got covered by a very-light grey surface layer and two new peaks appeared in its X-ray diffraction spectra confirming the appearance of a new phase.
60
80
100 T(K)
Fig. 2. Relative change of the volume of the superconducting phase during isochronal soaking, a - - as prepared, b - - 20min at 44 + I°C, c - - 20min at 51 ___ l°C, d I 2 0 m i n a t 6 6 + I°C.
Acknowledgements - - We would like to thank E. Pollert for the X-ray experiment. REFERENCES I.
2.
M.P.A. Viegers, H.A.M. van Hal, J.H.I. Hengst, C. Langereis, H.C.M. Smoorenburg, P.F. Bongers, W. Kadowaki, Y.K. H u a n g & A.A. Menovsky, European Materials Research Society Meeting, Strasbourg (1987) abstract. D.M. de Leeuw, C.A.H.A. Mutsaers, H.A.M. van Hal, C. Langereis, J.W.C. de Vries, A.W. Kolfschoten & P.H. Joosten, European Mat-
erials Research Society Meeting, Strasbourg, 3. 4.
(1987) abstract. I. Nakada, S. Sato, Y. Oda & T. Kohara, Jap. J. Appl. Phys. 26, L697-L698 (1987). O. Smr6kov~i, D. S2~korov~i, J. Dominec, K. Jurek & L. Smr6ka, Phys. Status Solidi (a) 103, K36 (1987).