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In our previous study, we showed that the anti-disproportionation properties of Zr 0.8 Ti 0.2-x Nb x Co alloys were remarkably improved by the co-substitution of Zr with Ti and Nb. However, the practical application of these alloys in handling of hydrogen isotopes necessitates the first hand knowledge of hydrogen isotope effect. Herein, we discuss the hydrogen isotope effect on storage properties of Zr 0.8 Ti 0.2-x Nb x Co alloys. According to PCT measurements on desorption of deuterium from the Zr 0.8 Ti 0.2-x Nb x Co deuterides and comparison with corresponding hydrides, the deuterides require relatively lower temperature to achieve the desired equilibrium pressure. DSC measurements reveal a significant decrease in the activation energy for hydrogen/deuterium desorption reactions when Zr is substituted with Ti and Nb. Furthermore, it is observed that the activation energy of deuterium desorption is lower than the desorption of hydrogen from analogous hydride. Isotope effect on isothermal disproportion studies on Zr 0.8 Ti 0.2-x Nb x Co-deuterides divulge that Zr 0.8 Ti 0.2-x Nb x Co-deuterides have superior anti-disproportionation properties over corresponding hydrides, and further improvement is anticipated for the Zr 0.8 Ti 0.2-x Nb x Co-tritides. This study revealed the significant impact of Ti and Nb co-substitution on hydrogen isotope storage properties of Zr 0.8 Ti 0.2-x Nb x Co alloys, making them potential candidates for handling hydrogen isotopes. • Hydrogen isotope effect on storage behavior of Zr 0.8 Ti 0.2-x Nb x Co alloys was investigated. • Normal hydrogen isotope effect is observed for Zr 0.8 Ti 0.2-x Nb x Co alloys. • Equilibrium pressure of D 2 was found to be higher than that of H 2. • Activation energy for D 2 desorption is found to be lower than H 2 desorption. • Remarkably high anti-disproportionation property was observed for Zr 0.8 Ti 0.2-x Nb x Co deuterides. [ABSTRACT FROM AUTHOR]

Considering the thermodynamic stability of various hydrides, a strategy has been employed to improve the hydrogen isotope storage properties of ZrCo alloy which involves partial co-substitution of Zr with Ti and Nb. Herein, alloys of composition Zr 0.8 Ti 0.2-x Nb x Co (x = 0.05, 0.1, 0.15) is prepared, characterized and the effect of Ti and Nb doping on hydrogen storage properties of parent ZrCo alloy is investigated. XRD analysis confirmed the formation of desired pure cubic phase of all the synthesized alloys similar to ZrCo phase. The presence of a single plateau in hydrogen desorption pressure-composition isotherms confirms single step hydrogen absorption-desorption behavior in Zr 0.8 Ti 0.2-x Nb x Co alloys. The equilibrium pressure of hydrogen desorption decreases marginally with increasing Nb content in Zr 0.8 Ti 0.2-x Nb x Co alloys which is further corroborated by differential scanning calorimetry measurements. Investigation of hydrogen induced disproportionation behavior in ITER-simulating condition revealed substantial impact of co-substitution of Ti and Nb on anti-disproportionation properties of ZrCo alloy. These remarkable properties make the Ti and Nb co-substituted quaternary alloys a desirable material for hydrogen isotope storage and delivery application. [Display omitted] • Prepared Zr 0.8 Ti 0.2-x Nb x Co alloys having single cubic phase. • Hydrogen storage behavior of Zr 0.8 Ti 0.2-x Nb x Co alloys was investigated. • Substitution of Zr with Ti and Nb significantly decreases the desorption temperature. • Zr 0.8 Ti 0.05 Nb 0.15 Co alloy has remarkably high anti-disproportionation properties. [ABSTRACT FROM AUTHOR]

Owing to the large hydrogen isotope effect, palladium and palladium based alloy are of great technological importance for their application in separation of hydrogen isotopes. The present study deals with the investigation of isotope effect on hydrogen desorption kinetics of Pd, Pd 0.77 Ag 0.23 and Pd 0.77 Ag 0.10 Cu 0.13 alloys, using non-isothermal method by employing Differential Scanning Calorimetry (DSC). Pd 0.77 Ag 0.23 and Pd 0.77 Ag 0.10 Cu 0.13 alloys were prepared by arc melting method and characterised by XRD, TXRF and EDS. Both the alloys are found to have FCC phase similar to Pd lattice. Prior to kinetic measurements, samples were activated by hydriding-dehydriding method. Hydrogen/deuterium desorption kinetic measurements were carried out at four different heating rates (8, 12, 16 and 20 K/min) and Kissinger plots were constructed from peak temperature of DSC curves. Activation energies for hydrogen/deuterium desorption from the corresponding hydride/deuteride were calculated from the slope of Kissinger plot which follows the order; Pd > Pd 0.77 Ag 0.23 > Pd 0.77 Ag 0.10 Cu 0.13. Activation energy for deuterium desorption was found to be lower than that of hydrogen desorption and significant isotope effect was observed for the Pd 0.77 Ag 0.10 Cu 0.13 alloy which makes it a favorable candidate material for its application in hydrogen isotope separation, employing self-displacement gas chromatography. • Pd 0.77 Ag 0.23 and Pd 0.77 Ag 0.10 Cu 0.13 alloys prepared and characterised. • Desorption kinetics of hydrides and deuterides were studied employing DSC. • Activation energy of desorption process was calculated using Kissinger plot. • Large isotope effect makes Pd–Ag–Cu alloy suitable for hydrogen isotope separation. [ABSTRACT FROM AUTHOR]