Superconductivity and enhancement of critical current density of Ta-substituted TlSr1212 with addition of nanosize MgO

• Published in: Materials research innovations 2009-09, Vol.13 (3), p.364-367, Article 364
• Main Authors: Yusof, M. I., Salleh, Z., Yahya, A. K., Jumali, M. H.
• Format: Article
• Language: English
• Subjects: CRITICAL CURRENT DENSITY; CRITICAL TEMPERATURE; FLUX PINNING; NANOSIZE MGO; TL1212 PHASE
• ISSN: 1432-8917; 1433-075X; 1433-075X
• DOI: 10.1179/143307509X441577

In this paper, the authors report the effect of nanosize MgO particles addition on superconducting and transport critical current density J c of TlSr1212 superconductors prepared from Tl 0·9 Bi 0·1 Sr 1·95 Ta 0·05 Ca 0·9 Y 0·1 Cu 2 O 7 starting composition using conventional solid state synthesis. X-ray diffraction analyses of Tl 0·9 Bi 0·1 Sr 1·95 Ta 0·05 Ca 0·9 Y 0·1 Cu 2 O 7 +xMgO (x=0 to 0·8 wt-%) showed formation of dominant 1212 phase (>90 vol.-%) together with minor 1201 phases. Undoped TlSr1212(x=0) was observed to superconduct with a zero-resistance critical temperature T c zero of 65 K. The x=0·2 sample recorded the highest T c zero (80 K) but for higher x, T c zero was gradually suppressed. The effect of the MgO addition also caused J c enhancement in zero field with highest value at x=0·2. Using the self-field approximation model, the variation of J c with temperature for x=0 to 0·4 samples indicate that MgO addition reduces the characteristics length L c associated with the pinning force. J c measurements in external magnetic field of 0-0·8 T showed smallest drop in J c at x=0·2. The J c enhancements in self-field and in the external fields are suggested to be due to increased flux pinning of the samples as a result of the MgO addition.