Correlation Between Enhanced T c , the Unit Cell Volume and AC Magnetic Shielding in Argon Preheated ( Y 1 - x Eu x ) ( SrBa ) Cu 3 O 6 + z

• Published in: IEEE transactions on applied superconductivity 2011-06, Vol.21 (3), p.2732-2736
• Main Authors: El Yakoubi, Essediq Youssef, Nafidi, Abdelhakim, Morghi, Redwane, Braigue, Mohamed, Chaib, Hassan, Hemine, Jamal, Vinod, MSrinivasa, Massaq, Mustapha, Suryanarayanan, Ramanathaan
• Format: Article
• Language: English
• Subjects: Annealing; Argon; Copper; Correlation; Electrical resistivity; Heat treatment; Order disorder; Strontium
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2010.2088372

We report here on the preparation, X-ray diffraction with Rietveld refinement, resistivity and AC magnetic susceptibility measurements of ( Y 1 - x Eu x ) ( SrBa ) Cu 3 O 6.94 . Each sample was subject to two types of heat treatment: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. For each x, the [AO] treatment increases the orthorhombicity epsilon (for 0 less than or equal to x less than or equal to 1 ), T c (for x greater than or equal to 0.45 ) and by 6 K to 87 K for x = 1 [AO], and the distance d [ Cu ( 1 ) - Sr / Ba ] (decrease T c ) for x < 0.4 and decrease it (increase T c ) for x Unknown character 0.4 . In the normal state, the [AO] treatment reduced the linear resistivity parameters indicating a diminution of the interaction of carrier charges with phonons. There was a remarkable improvement in the shielding effect S (amplitude of chi ' ( T ) ) in the case of the samples [AO] at all T Unknown character T c and for any applied field for x Unknown character 0.5 . For each x and heat treatment, S(x) decreases when H dc and the temperature increase. Remarkable correlations were observed. A combination of several factors such as decrease in d [ Cu ( 1 ) - ( Sr / Ba ) ] ; increase in cationic and chain oxygen ordering; p Sh and in-phase purity for the [AO] samples may account for the observed data.