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LaNi5In, NdNi5In and CeNi5In reversible hydrogen absorbers were hydrogenated at room temperature under hydrogen pressure up to 10.0 MPa, forming LaNi5InH1.8, NdNi5InH0.9 and CeNi5InH0.8 hydrides. These were characterised by X-ray diffraction. These hydrides have the same crystal structure as original metal matrix with slightly expanded unit cell (Δa⧸a0 = (0.4–0.8)%; Δc⧸c0 = (0.6–1.2)%; ΔV⧸V0 = (1.4–2.8)%. Isotherms of hydrogen absorption-desorption in LaNi5In–H systems were measured at 292.0, 328.5 and 355.5 K. Enthalpy change for reaction with hydrogen was determined. The values ΔH = −(35.9±2.2) kJ⧸(mole H2) on formation of the hydride and ΔH = (33.2±1.6) kJ⧸(mole H2) on reverse transition were obtained. The RNi4In (R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) do not interact with hydrogen under the above conditions. Catalytic influence of RNi5In phase on hydrogenation of the RNi4In phase was observed in the case of Pr-containing compounds. |
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