In situ investigation on transformation of valence on the surface of the Zr_0.9Ti_0.1V₂ alloy during thermal activation

The Zr_0.9Ti_0.1V ₂ ternary alloy was prepared by the electromagnetic induction levitation melting method. The surface chemical composition of the alloy was investigated by X-ray photoelectron spectroscopy. The superficial oxide layer of the air-exposed Zr _0.9Ti_0.1V ₂ alloy almost completely disappeared during the thermal activation process. With increasing temperature, oxidized V was the first activated component at 393 K followed by the activation of oxidized Ti at 473 K, while oxidized Zr was not activated until 533 K. The valence transformation mechanism from the oxidized state to the metallic state for the Zr_0.9Ti_0.1V ₂ alloy clarifies the reason why this alloy absorbs hydrogen immediately at high temperatures and exhibits a pseudo-balance at low temperatures.