Experimental evidence for orthorhombic Fddd crystal structure in elemental yttrium above 100 GPa

TL;DR

This study provides experimental evidence that elemental yttrium adopts an orthorhombic Fddd crystal structure above 100 GPa, supported by resistance measurements and X-ray data, advancing understanding of high-pressure phases and superconductivity.

Contribution

The paper offers the first experimental confirmation of the Fddd phase in yttrium above 100 GPa, combining resistance data and X-ray refinement.

Findings

Yttrium becomes superconducting above 100 GPa.

Superconducting transition temperature aligns with Fddd phase predictions.

Yttrium film evaporation method aids future superhydride synthesis.

Abstract

We present electrical resistance measurements of elemental yttrium on bulk and film samples, and both exhibit superconductivity at very high pressures. We show that the pressure dependence of the superconducting transition temperature above 100 GPa is in good agreement with the predicted Fddd phase by Chen et al. [Phys. Rev. lett. 109, 157004 (2012)]. This result together with a new Rietveld refinement made on X-ray data at 123 GPa from Samudrala et al. [J. Phys. Condens. Matter 24, 362201 (2012)] offer strong evidence that the atomic structure of yttrium above 100 GPa is orthorhombic Fddd. Furthermore, our process of evaporating yttrium film directly on a diamond anvil is expected to be a valuable asset for future synthesis of new superhydride superconductors.