Tuning the hydride stability of the TiVNb-based alloys by equimolar Cr/Al addition

Large Destabilization of (TiVNb)-Based Hydrides via (Al, Mo) Addition: Insights from Experiments and Data-Driven Models

“…The addition of 5–10 atom % Al in the TiVNb system destabilizes the hydride phase, while much larger amounts of Cr must be added to TiVNb (25–35 atom % Cr , ) to achieve the same effect. The use of Al/Cr in equal proportions in (TiVNb) 100– x (CrAl) x can even further destabilize the dihydride phase . Here, we have demonstrated that the addition of small amounts of Mo (5–10 atom %) can more substantially destabilize the hydride formation, with one of the smallest values reported for the enthalpy of hydride formation for Al 0.05 (TiVNb) 0.85 Mo 0.10 (Δ H abs = −37(±1) kJ/mol H 2 ).…”

“…lize the dihydride phase. 27 Here, we have demonstrated that the addition of small amounts of Mo (5−10 atom %) can more substantially destabilize the hydride formation, with one of the smallest values reported for the enthalpy of hydride formation for Al 0.05 (TiVNb) 0.85 Mo 0.10 (ΔH abs = −37(±1) kJ/mol H 2 ).…”

“…Nonetheless, further control in tuning the thermodynamics of the hydride formation (i.e., increasing the phase change/plateau pressure by reducing the enthalpy of desorption or increasing the entropy of desorption) is desired to improve their practical use as hydrogen storage materials. Despite its low hydrogen affinity and relatively important weight, molybdenum (bcc structure) has a significant potential to stabilize the bcc phases , and consequently to destabilize the related hydrides . Shen et al reported an increase in gravimetric capacity using up to 10 atom % Mo in the Ti 0.20 Zr 0.20 Hf 0.20 Mo 0.10 Nb 0.30 composition (1.54 wt %) compared to Ti 0.20 Zr 0.20 Hf 0.20 Nb 0.40 (1.12 wt %), as well as a decrease in thermal stability (reduction in the desorption temperature) with increasing Mo content, which was attributed to the smaller cell volume and weaker H-metal bonding .…”

“…Despite its low hydrogen affinity and relatively important weight, molybdenum (bcc structure) has a significant potential to stabilize the bcc phases 25,26 and consequently to destabilize the related hydrides. 27 Shen et al reported an increase in gravimetric capacity using up to 10 atom % Mo in the Ti 0.20 Zr 0.20 Hf 0.20 Mo 0.10 Nb 0.30 composition (1.54 wt %) compared to Ti 0.20 Zr 0.20 Hf 0.20 Nb 0.40 (1.12 wt %), as well as a decrease in thermal stability (reduction in the desorption temperature) with increasing Mo content, which was attributed to the smaller cell volume and weaker H-metal b o n d i n g . 2 6 S i m i l a r l y , B o u z i d i e t a l .…”

Effect of Cr/Mn Addition in TiVNb on Hydrogen Sorption Properties: Thermodynamics and Phase Transition Study

“…The as-cast (TiVNb) 0.90 Mn 0.05 Cr 0.05 alloy is a single-phase bcc material (Im3m) with a lattice parameter of 3.194(1) Å, as demonstrated by powder SR-XRD (Figure 1 and Table 1). For the sake of comparison, Table 1 lists the lattice parameters of closely related TiVNbbased compositions from the literature [14,25,26]. This lattice parameter value is inferior to 3.211 Å obtained for the ternary TiVNb alloy and closely related to other compositions in this alloy family (Table 1).…”