On the Feasibility of Strain-Induced Formation of Hollows during Hydriding or Oxidation of Metal Nanoparticles

Hydriding or oxidation of a metal nanoparticle starts on the surface and results in the formation of a hydride or oxide shell. Due to expansion of the shell, the strain in the metal core is tensile, and in principle it may induce the formation of a hollow structure (this hollow-formation mechanism is alternative to that based on the Kirkendall effect). Using the theory of elasticity, we show that this is feasible for oxides but not feasible for hydrides.