Superconducting Zirconium Polyhydrides at Moderate Pressures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity Research

Background:

• Highly compressed hydrides are key candidates for high-temperature superconductivity.
• Recent discoveries in H₃S and LaH₁₀± highlight the potential of hydride superconductors.
• The search for new superconductors in similar hydride systems remains an active area of research.

Purpose of the Study:

• To synthesize and characterize new zirconium hydride compounds.
• To investigate the superconducting properties of synthesized zirconium hydrides.
• To explore the potential of first-principles structure prediction in discovering novel superconductors.

Main Methods:

• First-principles structure prediction guided the synthesis.
• Synthesis of ZrH₃ and Zr₄H₁₅ was achieved in diamond anvil cells at 30-50 GPa using two reaction routes.
• Synchrotron X-ray diffraction was used for structural characterization, and electrical resistance measurements under magnetic fields were performed to determine superconducting transition temperatures (T_c).

Main Results:

• ZrH₃ was synthesized with a Pm3̅n (A15) structure, and Zr₄H₁₅ was synthesized with an I4̅3d (Th₄H₁₅-type) structure.
• Two distinct superconducting transitions were observed at 6.4 K and 4.0 K at 40 GPa.
• These transition temperatures are attributed to ZrH₃ and Zr₄H₁₅, respectively.

Conclusions:

• The study successfully synthesized and characterized two novel zirconium hydrides, ZrH₃ and Zr₄H₁₅.
• Both compounds exhibit superconductivity at moderate pressures, with distinct transition temperatures.
• This work demonstrates the efficacy of computational prediction in discovering new superconducting materials.