Nb3Sn正常-超导转变时的比热反常

在16.0°K—20.3°K之间测量了Nb₃Sn样品的热容量。Nb₃Sn在临界温度附近的比热跳跃值ΔC=2.21(±5％)焦耳/克分子·度。样品的临界温度T_c=17.88°K,转变宽度ΔT_c≈0.2°K。ΔC值利用热力学关系式确定了Nb₃Sn在0°K时的热力学临界场H₀=5300奥斯特。利用本文的结果和文献上关于热膨胀系数的跳跃值Δα及?T/?P值验证了热力学关系式。扼要地描述了比热测量装置.

SPECIFIC HEAT ANOMALY OF Nb3Sn AT THE NORMAL-SUPERCONDUCTING TRANSITION

The heat capacity of Nb₃Sn has been measured between 16.0°K and 20.3°K. A jump in specific heat at T_c is found with ΔC = 2.21 (±5%) joule/mole·deg. The transition temperature of the sample is T_c= 17.88°K, and the transition interval is ΔT_c ≈ 0.2°K. From the measured ΔC and by using the thermodynamic relationship, the thermodynamic critical magnetic field at 0°K, H₀≈5300 Oe, was obtained. Using the result of ΔC obtained in the present work, and the jump of the thermo-expansion coefficient Δα and (?T_c/(?p) from the literatures, the thermodynamic relation be-tween these quantities was found to be valid.Apparatus for measuring the specific heat is briefly described.