Comment on: Observation of a first order phase transition to metal hydrogen near 425 GPa

TL;DR

This paper critically evaluates claims of metallic hydrogen at 425 GPa, arguing that the evidence is insufficient and that prior studies have already reported similar findings at comparable pressures.

Contribution

It provides a critical commentary on recent claims of metallic hydrogen, emphasizing the lack of supporting evidence and referencing prior related research.

Findings

Previous studies reported metallic hydrogen at similar pressures.

The recent claim lacks conclusive evidence of an insulator-metal transition.

Multiple experiments have observed metallic behavior in hydrogen at high pressures.

Abstract

Loubeyre, Occelli, and Dumas (LOD) [1] claim to have produced metallic hydrogen (MH) at a pressure of 425 GPa, without the necessary supporting evidence of an insulator to metal transition. The paper is much ado about nothing. Most of the results have been reported earlier. Zha, Liu, and Hemley [2] studied hydrogen at low temperature up to 360 GPa in 2012; they reported absorption studies up to 0.1eV. Eremets et al [3] studied dense hydrogen up to 480 GPa using standard bevel diamonds. They reported darkening of the sample and electrical conductivity in which they reported semi-metallic behavior around 440 GPa. In 2016 Dias, Noked, and Silvera [4] reported hydrogen was opaque at 420 GPa. In 2017 Dias and Silvera observed atomic metallic hydrogen at 495 GPa in the temperature range 5.5-83 K [5].