Observation of new phases in Pd–D systems

Abstract

Deuterium thermal desorption spectra (TDS) were taken from Pd samples which were pre-implanted with different doses of 25 keV D 2 + ions at T irr∼100 K. The TDS were used to investigate the variations in deuterium concentration in Pd samples during their heating. The plotted annealing curves show a step-like structure typical of phase transitions. The phase composition variations were traced as the deuterium concentration in Pd increased from D/Pd=0 to D/Pd≈1. It was found that the β-phase (Pd β-hydride) was growing up to deuterium concentration D/Pd=0.5. At 0.5<D/Pd⩽1, a new phase ( γ-phase) was observed, which had thermodynamic characteristics much different from those of β-phase. The γ-phase formation causes the β-phase to modify into the β′-phase that has a lower decomposition temperature.