Effects of Thermal Cycling on the Physical Properties of VH_x

Abstract

A thousand thermal cycles of vanadium hydride across the β-γ mixed phase region decreased the reversible hydrogen storage capacity and increased the absorption/desorption pressure hysteresis ratio. Thermal cycling also produced a large increase in hydride surface area. Nevertheless, X-ray diffraction and transmission electron microscopy showed the measured crystalline size to be larger after the 1000 cycles than for activated materials. These results were not anticipated from the behavior exhibited by other metal hydrides.

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