PRESSURE-INDUCED SUPERCONDUCTIVITY AND PHASE-TRANSITION IN SELENIUM AND TELLURIUM

The pressure dependences of the electrical resistance and the superconducting transition temperature, T(c), in Se and Te have been measured up to 57 GPa and 42 GPa, respectively. A semiconductor-metal transition of Se and Te, which occurred at 23 GPa and 4 GPa, respectively, corresponded to the structural transition to monoclinic phase. The pressure dependence of T(c) of Se showed an anomaly at about 36 GPa, corresponding to a structural transition from monoclinic to orthorhombic phase. The T(c) of monoclinic-Se was 5.6 K at 26 GPa and independent of pressure. The T(c) of Te exhibited a significant enhancement at 35 GPa, which resulted from the structural transition from beta-Po type to bcc phase, and reached a maximum value of 7.4 K.