Superconductivity in the Ti-D system under pressure

The pressure dependence of the superconducting transition temperature in TiD_0.74 has been measured up to 30 GPa in a diamond high-pressure chamber. It is found that the deuteride TiD_0.74 becomes a superconductor at pressures corresponding to the transition to the high-pressure ζ 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 TiD_0.74 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 ζ phase under pressure to the region of the metastable state at atmospheric pressure. Fiz. Tverd. Tela (St. Petersburg) 40, 2153–2155 (December 1998)