Sains Malaysiana 38(3): 419-422

Kesan Penambahan Nano Ag Terhadap Suhu Genting dan

Pembentukan Fasa Superkonduktor  (Tl_0.85Cr_0.15)Sr₂CaCu₂O₇-_δ

(Effect of nano Ag addition on critical temperature and phase formation of  (Tl_0.85Cr_0.15)Sr₂CaCu₂O₇-_δ Superconductors)

W. Kong, A. K. Koh & R. Abd-Shukor*

School of Applied Physics, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E., Malaysia

Diserahkan: 6 Jun 2008 / Diterima: 8 Ogos 2008

ABSTRAK

Superkonduktor suhu tinggi berasaskan sistem (Tl_0.85Cr_0.15)Sr₂CaCu₂O₇-Ag_x (Tl1212) dengan komposisi x = 0.0, 0.01, 0.02, 0.03 dan 0.05 telah disediakan dengan kaedah tindak balas keadaan pepejal. Rintangan elektrik terhadap suhu telah diukur dengan kaedah penduga empat titik. Suhu genting mula, T_c-mula bagi sistem Tl1212 tanpa penambahan nano Ag adalah 113 K. Penambahan nano Ag menurunkan suhu genting sampel. Corak pembelauan sinar-X menunjukkan bahawa semua sampel mempunyai fasa dominan 1212. Sampel x = 0.02 mempunyai peratusan fasa 1212 yang tertinggi iaitu 87%.

Kata kunci: Nano Ag; suhu genting; superkonduktor Tl1212

ABSTRACT

The Tl1212 type phase high temperature superconductor (Tl_0.85Cr_0.15)Sr₂CaCu₂O₇-Ag_x with x = 0.0, 0.01, 0.02, 0.03 and 0.05 have been prepared through the solid-state reaction method. Samples were characterized by the four-point probe method for electrical resistance. The results show that the onset critical temperature, T_c-onset of the non-added sample is 113 K. The addition of nano Ag decreased the critical temperature. XRD patterns showed that the Tl1212 phase is dominant in all samples. Sample with x = 0.02 has the highest percentage of Tl1212 phase, which is 87%.

Keywords: Critical temperature; nano Ag; Tl1212 superconductor

RUJUKAN

Abd. Shukor, R. & Lo, S. V. 2001. Effect of Zn and Mn Substitutions on the Formationa and Superconductivity of Tl-1212 type phase (Tl_0.85Cr_0.15)Sr₂CaCu₂O₇. Journal of Materials Science Letters 20: 159-161.

Abd. Shukor, R. & Nik Jaafar, N. A. 1999. Formation and superconductivity of Pr and Nd-substituted Tl-1212 phase (Tl_0.85Cr_0.15)Sr₂CaCu₂O₇. Journal of Materials Science 10: 677-681.

Batlogg, B. & Varma, C. M. 2000. The Underdoped Phasa of Cuprate Superconductirs. Physics World 13(2): 33-38.

Chan Park, Sayya, S. S., Sviram, D. & Zinder, R.L. 1995. Effect of silver addition on the processing of (Tl_0.5Pb_0.5)Sr₂CaCu₂O₇. Journal of Applied Superconductivity 3:139-146.

Eder, M. & Gritzner, G. 2005. Thallium-based cuprate superconductors doped with rare earth oxides. Superconductor Science  and Technology 18: 87-91.

Guo, Y.C., Liu, H.K. & Dou, S.X. 1993. Silver-doped (Bi, Pb)₂Sr₂Ca₂Cu₃O₁₀/Ag high-temperature superconductivity composites. Physica C 215: 291-296.

Hari Babu N, Lida K., Dardwell D.A. 2007. Flux Pinning in Melt-processed Nanocomposite Single Grain Superconductors. Superconductor Science & Technology 20: S141-S146.

Iqbal, Z., Ramakrishna, B.L. & Barry, J.C. 1990. Synthesis, Microstucture and Superconducting Properties of Ce-doped Tl-Sr-Ca-Cu-O. Physica C 196: 396-400.

Karaca, I. , Celebi, S., Vaviki, A. & Malik, A. I. 2003. Effect of Ag₂O Addition on the Intergranular Properties of the Superconductivity Bi-(Pb)-Sr-Ca-Cu-O System. Superconductor Science and Technology 16: 100-104.

Kao, Y. H., Yao, Y.D., Jang, L.Y, Xu, F., Krol, A., Song, L.W., Sher, C.J., Daravsky,  A., Philips, J.C., Simmuns, J. J. & Snyder, R. L. 1990. Effects of Silver Doping in the high-T Superconductor System Y-Ba-Cu-O. Journal of Applied Physics 67:355-361.

Letouze, F., Hervieu, M., Martin, C., Maignan, A. & Raveau, B. 1998. Local ordering of the chromate groups in the “1212” superconductor Tl_0.9(CrO₄)_0.2Sr₂Ca_0.9Cu₂O_6.2-∂. Physica C 296: 195-204.

Lee, W. H. & Huang, B. C. 1997. Changes in doping state of Tl(Sr_2-xR_x)CaCu₂O_7-∂     (R=Sm, Eu, Dy) system. Physica C 289: 114-122.

Li, Y. F., Chmaissem, O. & Sheng, Z. Z. 1995. Crystal structure and T_c of 1212-type cuprate (Tl,Cr)Sr₂(Ca, Tl)Cu₂O₇, Physica C 248: 42-48.

Ren, Y., Meng, J., Niu, M. & Zeng, Z 1990. Structure and Superconductivity for YBa₂Cu₃O₇-Ag_x. Solid State Communications 76: 1103-1105.

Saito, Y., Noji, T., Endo, A., Niguchi, Ni, Fujimoto, K., Oikawa, T., Hattori, A. &  Furuse, K. 1987. Composition dependence of superconductivity in  Y-Ba-(Ag,Co)-O system. Japanese Journal of Applied Physics 26: L832-L833.

Savvides, N. Katsaros, A. & Dou, S. X. 1991. Critical current density and flux pinning in silver/superconductor composites and Tapes. Physica C 179: 361-368.

Wu, N. L. & Chang, Y. C. 1990. Silver-enhanced syntesis of YBa₂Cu₃O_7-x. Japanese Journal of Applied Physics 29: L563-L565.

*Pengarang unttuk surat menyurat; email:ras@ukm.my