Synthesis of superconducting hcp-ZrH3 under high hydrogen pressure

Zirconium trihydride and, for comparison, trideuteride with hexagonal close-packed (hcp) metal lattices were synthesized at a hydrogen/deuterium pressure of 9 GPa and a temperature of 873 K using toroid-type high-pressure chambers. After a rapid cooling (quenching) to 100 K and lowering the pressure to atmospheric, the quenched sample was removed from the chamber and studied by hot extraction analysis, powder x-ray diffraction, and ac magnetic susceptometry. The hot extraction showed that thermal decomposition of both hcp-ZrH3 and hcp-ZrD3 in vacuum begins after heating at a rate of 10 K/min to similar to 200 K and almost ceases at 270 K, leaving tetragonal epsilon-ZrH2/epsilon-ZrD2 as a result. The x-ray diffraction study at 85 K gave lattice parameters a = 3.443(2) angstrom and c = 5.964(4) angstrom for hcp-ZrH3 and somewhat smaller values of a = 3.430(5) angstrom and c = 5.947(5) angstrom for hcp-ZrD3. The measurements of magnetic susceptibility revealed superconductivity with an onset at 11.6(1) K for hcp-ZrH3 and 9.5(2) K for hcp-ZrD3.

Automated summary

Zirconium trihydride and trideuteride with hexagonal close-packed metal lattices were synthesized, and their thermal decomposition and superconductivity properties were studied. The results showed that the samples decomposed into tetragonal epsilon-ZrH2/epsilon-ZrD2 at temperatures near 200 K and exhibited superconductivity at temperatures of 11.6(1) K and 9.5(2) K, respectively.