Thermodynamic and magnetic properties of Pd_0.93Ag_0.07 hydride

Thermodynamic and magnetic properties of the Pd_0.93Ag _0.07 hydrides were measured. The isotherms of Pd _0.93Ag_0.07 -H and -D systems in the temperature range 373-523 K showed the plateau regions to be within 0.05 < [Q (Q = H or D)]/[Pd_0.93Ag_0.07] < 0.4. From an investigation of the thermodynamic isotope effect for the formation and decomposition of hydride, the enthalpy changes, ΔHβ-α, for desorption of hydrogen and deuterium were evaluated to be 43.0kJ/mol_H2 and 36.4kJ/mol _D2. respectively. It was observed that the magnetization of Pd _0.93Ag_0.07 H_x at ambient temperature increased with increasing magnetic field. Since the magnetization was not saturated up to 7 T, it can be concluded that Pd_0.93Ag_0.07H_x is paramagnetic. The magnetic susceptibility of Pd_0.93Ag _0.07H_x progressively decreased with increasing hydrogen content and vanished at [H]/[Pd_0.93,Ag_0.07] = 0.4. The disappearance of the susceptibility coincided with the termination of the plateau region of the isotherms. This fact can be explained by the rigid hand model, according to which the vacant part of d-band of Pd_0.93Ag _0.07 can accept electrons from absorbed hydrogen atoms.