Superconductivity in the Ti-D system under pressure

The pressure dependence of the superconducting transition temperature in TiD0.74 has been measured up to 30 GPa in a diamond high- pressure chamber. It is found that the deuteride TiD0.74 becomes a superconductor at pressures corresponding to the transition to the high- pressure zeta phase, with a transition temperature that increases from 4.17 to 4.43 K in the interval P = 14-30 GPa. The value extrapolated to atmospheric pressure T-c(0) = 4.0 K is significantly lower than the superconducting transition temperature (T-c = 5.0 K) measured earlier in the metastable state obtained by quenching TiD0.74 under pressure. It is assumed that the significant difference of the extrapolated value from the superconducting transition temperature in the metastable state after quenching under pressure is caused by a phase transition on the path from the stability region of the zeta phase under pressure to the region of the metastable state at atmospheric pressure. (C) 1998 American Institute of Physics. [S1063-7834(98)00212-3].