Solid State Science and Technology, Vol. 12, No 1 (2004) 113-119

SUPERCONDUCTIVITY OF Tl0.8Bi0.2Sr2Ca0.8Y0.2Cu2Oδ CERAMICS PREPARED VIA CO-PRECIPITATION METHOD

 

F. Md. Salleha*, M.H. Jumalib and A. K. Yahyaa

 

aFaculty of Applied Science, Universiti Teknologi MARA,

40450 Shah Alam, Selangor, Malaysia

 

bSchool of Applied Physics, Universiti Kebangsaan Malaysia,

43600 Bangi, Selangor, Malaysia

 

Email : faizahay@hotmail.com

 

 

 

ABSTRACT

 

In this paper, synthesis of Tl0.8Bi0.2Sr2Ca0.8Y0.2Cu2O7 superconductors via co-precipitation route is reported. Acetates of thallium, bismuth, strontium, calcium, yttrium and copper were mixed according to required stoichiometric ratios and reacted to form oxalates precipitates. The precipitates were subjected to various heating conditions for best conversion to oxides and carbonates. The co-precipitated powders were placed in an open crucible (CPR2 sample), in a closed crucible (CPR1 sample) and pressed into pellet form (CPR3 sample) before calcination at 600oC. CPR4 sample was prepared using excess thallium acetate in the starting solution composition and CPR5 sample was prepared by direct addition of Tl2O3 powder to the co-precipitated powder before sintering. All the samples were sintered at 980oC for 5 minutes in flowing oxygen. Temperature dependent electrical resistance (dc) measurements showed semiconductor-like normal state behavior for CPR1, CPR2 and CPR3 with Tconset between 94 K 108 K and Tc zero between 29 K 70 K. Addition of 10 wgt% excess Tl2O3 (CPR5 sample)   increased   Tc zero  to 74 K and showed semiconductor-semimetallic normal state behavior. CPR4 which was prepared with excess thallium acetate showed metallic normal state behavior and Tc zero of 80 K. The values of transport critical current density (Jc) of the samples determined by four-point-probe measurement using the 1μVcm-1 criterion are reported. X-Ray diffraction analysis showed formation of dominant 1212 phase in all co- precipitated samples. The effects of preparation procedures and addition of extra thallium in the starting composition on superconducting properties and Tl1212 phase formation are discussed.

 

http://journal.masshp.net/wp-content/uploads/Journal/2004/F.%20Md.%20Salleh%20113-119.pdf

 

 

 

 

 

REFERENCES

 

[1]        Rao C.N.R, Nagarajan R and Vijayaraghavan R, Supercond. Sci. Technol., 6, (1993), p 1

[2]       Van Beal M.K., Knaepen E., Kareiva A. et al., Supercond. Sci. Technol., 11, (1998),

82-87

[3]       Halim S.A., Khawaldeh S.A., Mohamed S.B. and Azhan H., Materials Chemistry and

Physics, 61, (1999), p251

[4]       Chen Y.F. and Sheen S.R., J. Chinese Chemical Society, 47, (2000), 307-314

[5]        Liang J.M., Liu R.S., Huang Y.T., Wu S.F., Wu P.T. and Chen L.J., Physica C, 165 , (1990), p347-353

[6]        Huang Y.T., Liu R.S., Wang W.N. and Wu P.T. Jap. J. Appl. Phys., 28, No 9, (1989), p L1514-L1517

[7]        Liu R.S., J Chen.M. and Liang W.Y., Physica C, 282-287, (1997) p981-982 [8]    Bernhard K and Gerhard G, Physica C, 196 (1992) p 259

[9]       Stephen A. Skirius et al, Applied Superconductivity, Vol 2, (1994) p127

[10]     Aselage T.L., Venturini E.L., Van Deusen S.B., Headley T.J., Eatough M.O., and

Voigt J.A.,  Physica C, 203 (1992) p25