THE RELATIONS OF SPECIFIC-HEAT ANOMALY WITH VARIATION OF OXYGEN-CONTENT IN BISRCACUO(2212)

We have investigated the phase transition of Bi1.8Pb0.2Sr2CaCu2O8 samp les with specific heat in low temperature. The phase transition temper atures depend on the oxygen contents. There is a relation between the specific heat anomaly and the oxygen contents in these samples. The sp ecific heat anomaly peak is the largest for the optimum doped sample, the anomaly peaks are decreased for the underdoped samples. There are the phase segregation phenomenon when the oxygen is removed content in these Bi2212 system samples, their transition temperatures are about 60K and 90K. The peak of specific heat anomaly for the overdoped sampl e (Tc=60K) does not appeared. The resistance measurement shows that th e phase transition temperature of these samples are the same as that o f the specific heat measurement. The electronic specific heats C-e and the Debye temperature theta(D) are calculated.