Solid State Science and Technology, Vol. 17, No 1 (2009) 182-188
Mg STOICHIOMETRY STUDY ON MgB2 AT LOW ANNEALING TEMPERATURES
M.A.M. Faisal1, S.A. Halim1, S.K. Chen1, R. Abd-Shukor2, M.I. Adam1,
M.M. Awang Kechik1, M.M. Kamarulzaman1, S.S.H. Ravindi1 and H. Baqiah1
1Department of Physics, Universiti Putra Malaysia,
43400 UPM Serdang, Selangor
2School of Applied Physics, Universiti Kebangsaan Malaysia,
43600 UKM Bangi, Selangor
An in-situ reaction of Magnesium (Mg) and Boron (B) at 650°C annealing temperature was used to compare the phase formation of Magnesium Diboride (MgB2) by varying the nominal Mg. The x-ray diffraction pattern indicates that Magnesium Oxide (MgO) is the major secondary phase. Some of the unreacted Mg phase was found in the nominal MgB2 stoichiometry and the Mg-excessed samples annealed at 650°C. However, no unreacted Mg was detected by XRD for Mg-deficient sample annealed at 650°C. Highest enhancement of critical current density (Jc) at 5 K and 20 K is found in Mg-deficient samples treated at both annealing temperatures. Jc is increased for the over-added Mg samples as compared to that of the nominal samples. The SEM image show a hexagonal grain structures with nano thickness distributions.
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