The formation of hydrogenated yttrium nanoparticles

Abstract

Nanoparticles of yttrium (Y) and YH3−x (with the composition varying from x<1 to x≪1) and the chemical reactions of these particles with hydrogen (YH2↔YH3) were studied. Yttrium nanoparticles with an average size of ∼25 nm were synthesized by method of laser ablation in an argon atmosphere. The particles deposited onto quartz substrates were exposed to H2 at room temperature and various pressures. The phase composition of the hydrogenated nanoparticles was determined by optical density measurements in situ. In the initial stage (low H2 pressures), the interaction of yttrium with hydrogen leads to the formation of stable metal-like YH2 dihydride nanoparticles. As the hydrogen pressure increases, the YH2 particles transform into dielectric nanoparticles with the composition YH3−x. The reaction YH2↔YH3, corresponding to the metal-dielectric phase transition in the nanoparticles, is reversible with respect to the H2 pressure in the gas phase.