Reversible metal-hydride phase transformation in epitaxial films

Area of Science:

• Materials Science
• Solid-state Chemistry
• Nanotechnology

Background:

• Metal-hydride phase transformations typically exhibit hysteresis, hindering reversible operation.
• Extrinsic hysteresis arises from energy dissipation via plastic deformation and fracture.
• Nanoscale mitigation is possible but introduces intrinsic thermodynamic hysteresis.

Purpose of the Study:

• To investigate the elimination of thermodynamic hysteresis in metal-hydride transformations.
• To explore the role of substrate constraint in epitaxial films for reversible phase transformations.

Main Methods:

• Theoretical analysis of phase transformations under substrate constraint.
• Modeling of heterophase polydomain nanostructure formation.
• Simulation of reversible phase fraction changes with temperature and chemical potential.

Main Results:

• Substrate constraint in epitaxial films eliminates intrinsic thermodynamic hysteresis.
• Film-substrate interaction induces a heterophase polydomain nanostructure.
• Reversible changes in phase fraction are achieved by varying temperature or chemical potential.

Conclusions:

• Epitaxial metal-hydride films offer a pathway to overcome thermodynamic hysteresis.
• Substrate-induced nanostructures enable reversible metal-hydride transformations.
• This approach has implications for advanced energy storage and hydrogen technologies.