Sonochemical hydrogenation of metallic microparticles

We report the sonochemical synthesis of hydrogenated metallic microparticles through room-temperature ultrasonic irradiation of aqueous metallic slurries. The role of saturating gases and of reduction-oxidation mechanism on promoting the hydride formation is investigated. The method is then applied to study the synthesis of different metallic hydrides (Mn, Ti) and the hydrogenation of La(Fe,Mn,Si)13, an intermetallic compound with magnetocaloric properties used in magnetic refrigeration applications. The samples were characterized by X-ray diffraction to identify the presence of hydrogenated phases, by differential scanning calorimetry to evaluate hydrogen release and temperature stability of the hydrides and by electron microscopy to identify morphological modifications induced by acoustic cavitation. The hydrogenation of metallic microparticles and intermetallic compounds is reported for the first time by means of this experimental technique which could represent a new tool for fast and cheap hydrogenation of materials for different technological applications, such as hydrogen storage and magnetic refrigeration.