Steric quenching of the switchable mirror effect Phys. Rev. B 75, 104109 (2007)

TL;DR

This study investigates how substituting scandium for yttrium in Y_(1-z)Sc_(z)H_(x) alloys affects the metal-insulator transition, revealing a critical unit cell volume below which the transition is quenched.

Contribution

It demonstrates the impact of unit cell size on the optical and electrical properties of Y-Sc hydrides and identifies a formation boundary related to scandium concentration.

Findings

Optical transmittance decreases for z>0.10

Electrical resistivity confirms transition from trihydride to dihydride

Critical unit cell volume correlates with Sc concentration

Abstract

Scandium was substituted for yttrium to observe the effect of unit cell size on the optical metal-to-insulator (MIT) transition in the Y_(1-z)Sc_(z)H_(x) alloy system. The optical transmittance decreases significantly for z>0.10. Simultaneous electrical resistivity measurements confirm the transition from trihydride to dihydride behavior with increasing z. These observations imply a quenching of the MIT when the unit cell volume falls below a critical level that is consistent with the boundary between trihydride and non-trihydride forming rare-earth elements. A combinatoric model reveals this formation boundary corresponds to two or more Sc per unit cell.