Study of synthesis technology and superconductivity of MgB2

For fabricating a dense and superconducting bulk MgB2 samples, a synthesis technique was employed. Our experimental results show that there is a suitable sintering temperature range, say from 800 to 850 degreesC. In this temperature range, the critical temperature of the samples is 38 K above, and the superconducting transition is sharper than that of those sintered out of the range. The temperature dependence of resistance of MgB2 in high temperature region was also measured. The temperature dependence of the resistance, at temperature lower than 700 degreesC, obeys a form of a + bT(n), where n similar to 2.9. However, the resistance of the sample exhibits a negative. temperature coefficient, as T is higher than 700 degreesC. This indicates that MgB2 has semiconducting behavior. (C) 2002 Elsevier Science B.V. All rights reserved.