Synthesis of technetium hydride TcH$_{1.3}$ at 27 GPa

TL;DR

This study synthesizes and characterizes a new nonstoichiometric technetium hydride TcH$_{1.3}$ at 27 GPa, revealing its structure, optical properties, and lack of superconductivity through experimental and theoretical methods.

Contribution

It reports the first synthesis and structural analysis of TcH$_{1.3}$ at high pressure, expanding understanding of technetium hydrides and their properties.

Findings

TcH$_{1.3}$ is a new hexagonal hydride formed at 27 GPa.

Technetium hydrides show increased hydrogen content with pressure.

TcH$_{1+x}$ do not exhibit superconductivity due to low electron-phonon coupling.

Abstract

In this work, we synthesize and investigate lower technetium hydrides at pressures up to 45 GPa using the synchrotron X-ray diffraction, reflectance spectroscopy, and ab initio calculations. In the Tc-H system, the hydrogen content in TcH$_x$ phases increases when the pressure rises, and at 27 GPa we found a new hexagonal (hcp) nonstoichiometric hydride TcH$_{1.3}$. The formation of technetium hydrides is also confirmed by the emergence of a new reflective band at 450-600 nm in the reflectance spectra of TcH$_x$ samples synthesized at 45 GPa. On the basis of the theoretical analysis, we proposed crystal structures for the TcH$_{0.45 \pm 0.05}$ (Tc$_{16}$H$_7$) and TcH$_{0.75 \pm 0.05}$ (Tc$_4$H$_3$) phases previously obtained at 1-2 GPa. The calculations of the electron-phonon interaction show that technetium hydrides TcH$_{1+x}$ do not possess superconducting properties due to the low electron-phonon interaction parameter ($\lambda \sim 0.23$).