The successful and fast start-up of proton exchange membrane fuel cells (PEMFCs) at subfreezing temperatures (cold start) is very important for the use PEMFCs as energy sources automotive applications. effective thermal management major importance. When hydrogen stored in hydride-forming intermetallics, significant amounts heat are released due to exothermic nature reaction. This excess can pot...

The discovery of the 1144-phase, e.g. CaKFe$_4$As$_4$, creates opportunities to build novel intermetallics with alternative stacking two parent compounds. Here we formalize idea by defining a class bulk crystalline solids $A$-$B$ (including 1144-phases and beyond), which is generalization hetero-structures from few-layer or thin-film semi-conductors intermetallics. Theoretically, four families ...

We show that the existence of stable, ordered 3d-5d intermetallics CuAu and NiPt, as opposed to the unstable 3d-4d isovalent analogs CuAg and NiPd, results from relativity. First, in shrinking the equilibrium volume of the 5d element, relativity reduces the atomic size mismatch with respect to the 3d element, thus lowering the elastic packing strain. Second, in lowering the energy of the bondin...