Synthesis of technetium hydride TcH1.3 at 27 GPa

In this work, we synthesize and investigate lower technetium hydrides at pressures up to 45 GPa using synchrotron x-ray diffraction, reflectance spectroscopy, and ab initio calculations. In the Tc-H system, the hydrogen content in $\mathrm{Tc}{\mathrm{H}}_{x}$ phases increases when the pressure rises, and at 27 GPa we found a hexagonal (hcp) nonstoichiometric hydride $\mathrm{Tc}{\mathrm{H}}_{1.3}$. The formation of technetium hydrides is also confirmed by the emergence of a reflective band at 450--600 nm in the reflectance spectra of $\mathrm{Tc}{\mathrm{H}}_{1+x}$ samples synthesized at 45 GPa. On the basis of theoretical analysis, we propose crystal structures for the phases $\mathrm{Tc}{\mathrm{H}}_{0.45\ifmmode\pm\else\textpm\fi{}0.05} ({\mathrm{Tc}}_{16}{\mathrm{H}}_{7})$ and $\mathrm{Tc}{\mathrm{H}}_{0.75\ifmmode\pm\else\textpm\fi{}0.05} ({\mathrm{Tc}}_{4}{\mathrm{H}}_{3})$ previously obtained at 1--2 GPa. Calculations of the electron-phonon interaction show that technetium hydrides $\mathrm{Tc}{\mathrm{H}}_{1+x} (x=0--0.3)$ do not possess superconducting properties due to low electron-phonon interaction parameter $(\ensuremath{\lambda}\ensuremath{\sim}0.23)$.