A search for quantum phenomena of hydrogen in palladium at low temperatures; specific heat and torsional oscillator experiments Original Research Article

Hydrogen (H/D) atoms in palladium are known to have large diffusion coefficient due to quantum tunneling even at low temperatures. When the density of H/D is increased, we may expect macroscopic quantum phenomena because of possible overlap of hydrogen wave functions and quantum statistics. To investigate the phase diagram of hydrogen in Pd, specific heat measurements have been made for Pd–H systems with up to high hydrogen concentration specimens. And torsional oscillator (T.O.) experiments have been being performed to study hydrogen dynamics in the system. We discuss the long known so called 55 K anomaly as different phenomena from classical interpretation of order-disorder transition of hydrogen.