Pressure-composition and electrical resistance-composition isotherms of palladium-deuterium system

Abstract

The equilibrium deuterium pressure and the relative electrical resistance, R Ro , as a function of D Pd content during absorbtion-desorbtion processes of the Pd-D system, has been investigated at temperatures of 348, 373, 403 and 423 K up to a deuterium pressure of 3.3 MPa by a gas phase method. In the α single phase region for the absorbtion processes, R Ro shows a very large increase with increasing D Pd content. Achievement of R Ro values depends on exact equilibrium pressures, and attains ( R Ro ) α max values slowly after a long time. In the (α + β) two-phase region, R Ro shows almost constant values. In the β single phase region, R Ro again increases with increasing D Pd content. In the β phase region for the desorption processes, R Ro gradually decreases with decreasing D Pd content down to β min. On entering into the (α + β) two-phase region, R Ro values remain almost constant and show equal values to those of the absorbtion values. A small increase of R Ro occurs from a D Pd content of about 0.20, and maximum values attain at ( α + β) α boundary compositions. In the α phase region, R Ro values quickly decrease with decreasing D Pd content. Increments of temperature show decreases of R Ro values at different boundary compositions and in (α + β) two-phase regions. Presently observed R Ro behaviors for the Pd-D system show similarity with those reported previously for the Pd-H system.