Sains Malaysiana 37(3):  223-225 (2008)

Enhanced Critical Current Density in MgB₂ with

Dy₂O₃ Particle Additions

(Peningkatan Ketumpatan Arus Genting dalam MgB₂

dengan Penambahan Zarah Dy₂O₃)

Soo Kien Chen, Abdul Halim Shaari, Kean Pah Lim & Mohd Faisal Mohd Aris

Physics Department, Faculty of Science, Universiti Putra Malaysia,

43400 Serdang, Selangor, Darul Ehsan, Malaysia

Received: 12 Jun 2007 /Accepted: 19 November 2007

ABSTRACT

This paper reports on the effect  of oxide particle Dy₂O₃ additions on the superconducting properties of MgB₂. The polycrystalline samples were prepared by well mixing magnesium and boron elemental powders, followed by heat treatment for in situ reaction in inert gas environment. All the samples showed MgB₂ as the main phase with MgO and DyB₄ as impurities. Magnetization measurements showed that the superconducting transition temperature, T_c remained largely unchanged (37.5 – 38K) even for Dy₂O₃ additions up to 15.0 wt.%. However, the transition curve was broadened in samples with larger amount of additions. The best sample with only 0.5 wt.% Dy₂O₃ additions had a J_c of around a factor of 4 higher compared to the pure sample at 6K(1T). Tem imaging showed the distribution of nano precipitates of DyB₄ and MgO within the grain which may improve the pinning leading to enhancement in critical current density, J_c.

Keywords: MgB₂; critical current density; nano precipitates

ABSTRAK

Kertas ini melaporkan  kesan penambahan serbuk oksida Dy₂O₃  terhadap ciri-ciri kesuperkonduksian MgB₂. Sampel polikristal telah disediakan dengan mencampur serbuk magnesium and boron diikuti dengan rawatan pemanasan bagi menghasilkan tindakbalas in situ dalam persekitaran gas lengai. Semua sampel menunjukkan MgB₂ sebagai fasa dominan dengan kehadiran MgO dan DyB₄ sebagai fasa-fasa ketaktulenan. Pengukuran kemagnetan menunjukkan suhu genting, T_c tidak mengalami perubahan besar (37.5 – 38K) walaupun dengan penambahan Dy₂O₃ sehingga 15.0 wt.%. Walau bagaimanapun, lengkung peralihan suhu genting bertambah luas untuk sampel dengan panambahan serbuk oksida yang tinggi. Sampel yang terbaik dengan hanya penambahan 0.5 wt.% Dy₂O₃ mempunyai J_c pada 6K(1T) sebanyak empat kali ganda lebih tinggi berbanding dengan sampel tulen. Imej tem menunjukkan taburan mendakan DyB₄ dan MgO yang bersaiz nano dalam butiran yang memperbaiki kesan pengepinan dan seterusnya meningkatkan ketumpatan arus genting, J_c.

Kata kunci: MgB₂; ketumpatan arus genting; mendakan nano

REFERENCES/RUJUKAN

Buzea, C. & Yamashita, T. 2001. Review of the superconducting properties of MgB₂. Superconductor Science and Technology 14: R115-46.

Chen, D. X. & Goldfarb, R. B. 1989. Kim Model for magnetization of type-II superconductors. Journal of Applied Physics 66: 2489-2500.

Chen, S.K., Wei, M. & MacManus-Driscoll, J.L. 2006. Strong pinning enhancement in MgB₂ using very small Dy₂O₃ additions. Applied Physics Letters 88: 192512-1-3.

Dou, S.X., Soltanian, S., Horvat, H., Wang, X. L., Zhou, S. H., Ionescu, M., Liu, H.K., Munroe, P. & Tomsic, M. 2002. Enhancement of the critical current density and flux pinning of MgB₂ superconductor by nanoparticle SiC doping. Applied Physics Letters 81: 3419-3421.

Eom, C.B., Lee, M.K., Choi, J.H., Belenky, L.J., Song, X., Cooley, L.D., Naus, M.T., Patnaik, S., Jiang, J., Rikel, M., Polyanskii, A., Gurevich, A., Cai, X.Y., Bu, S.D., Babcock, S.E., Hellstrom, E.E., Larbalestier, D.C., Rogado, N., Regan, K.A., Hayward, M.A., He, T., Slusky, J.S., Inumaru, K., Haas, M.K., & Cava, R.J. 2001. High critical current density and enhanced irreversibility field in superconducting MgB₂ thin films. Nature 411: 558-60.

Kovác, P., Husek, I., Melisek, T., Grivel, J.C., Pachla, W., Strbík, V., Diduszko, R., Homeyer, J. & Andersen, N.H. 2004. The Role of MgO content in ex situ MgB₂ wires. Superconductor Science and Technology 17: L41-L46.

Nagamatsu, J., Nakagawa, N., Muranaka, T., Zenitani, Y. & Akimitsu, J. 2001. Superconductivity at 39 K in Magnesium Diboride. Nature 410: 63-64.

Serquis, A., Liao, X. Z., Zhu, Y.T., Coulter, J.Y., Huang, J.Y., Willis, J.O., Peterson, D.E., Mueller, F.M., Moreno, N.O., Thompson, J.D., Nesterenko, V.F. & Indrakanti, S.S. 2002. Influence of microstructures and crystalline defects on the superconductivity of MgB₂. Journal of Applied Physics 92: 351-56.

Wang, J., Bugoslavsky, Y., Berenov, A., Cowey, L. Caplin, A.D., Cohen, L.F., MacManus-Driscoll, J.L., Cooley, L.D., Song, X. & Larbalestier, D.C. 2002. High critical current density and improved irreversibility field in bulk MgB₂ made by a scaleable, nanoparticle addition route. Applied Physics Letters 81: 2026-28.

Wang, X. L., Soltanian, S., James, M., Qin, M.J., Horvat, J., Yao, Q.W., Liu, H.K. & Dou, S.X. 2004. Significant enhancement of critical current density and flux pinning in MgB₂ with nano-SiC, Si, and C doping. Physica C.  408-410: 63-67.