No observation of lead hydride in the Pb–H system under pressure up to 140 GPa

Abstract

The possibility of high pressure formation of lead hydrides has been investigated through the direct reaction of lead with hydrogen in a laser-heated diamond anvil cell. Synchrotron x-ray diffraction was used to detect any structural changes and volume expansion due to hydrogen absorption in the Pb metal. The compression curve of lead embedded in helium, measured under the same experimental conditions, was used as a reference. No volume expansion of the Pb lattice was measured, hence indicating no formation of an interstitial hydride. The observed structural changes match those of pure lead with the sequence of compact structures $fcc$ , $hcp$ , and $bcc$ . The ${\mathrm{PbH}}_6$ and ${\mathrm{PbH}}_4$ compounds, found by various crystal structure prediction calculations to be stable below 140 GPa, were not observed. Lead seems very reluctant to absorbing hydrogen, which could be used for plating materials to resist hydrogen embrittlement under extreme conditions.