High-pressure Phase Stability and Superconductivity of Pnictogen Hydrides and Chemical Trends for Compressed Hydrides

TL;DR

This study predicts high-pressure stability and superconductivity in pnictogen hydrides, identifying SbH₄ and AsH₈ as potential high-temperature superconductors above 100 K at megabar pressures, and explores chemical trends influencing these properties.

Contribution

The paper provides first-principles predictions of stable structures and superconducting properties of pnictogen hydrides under high pressure, revealing new candidate superconductors and chemical insights.

Findings

SbH₄ and AsH₈ are predicted to be high-temperature superconductors above 100 K.

SbH₄ is stabilized above about 150 GPa in a hexagonal structure.

Phosphorus hydrides are metastable and decompose into elements within studied pressures.

Abstract

Binary hydrides formed by the pnictogens of phosphorus, arsenic and antimony are studied at high pressures using first principles methods. Stable structures are predicted and their electronic, vibrational and superconducting properties are investigated. We predict that SbH$_{4}$ and AsH$_{8}$ will be high-temperature superconductors at megabar pressures, with critical temperatures in excess of 100 K. The highly symmetric hexagonal SbH$_{4}$ phase is predicted to be stabilized above about 150 GPa, which is readily achievable in diamond anvil cell experiments. We find that all phosphorus hydrides are metastable with respect to decomposition into the elements within the pressure range studied. Trends based on our results and literature data reveal a connection between the high-pressure behaviors and ambient-pressure chemical quantities which provides insight into understanding which elements may form hydrogen-rich high-temperature superconducting phases at high pressures.