Design and Synthesis of Clathrate LaB8 with Superconductivity

TL;DR

This paper reports the synthesis of a new boron-based clathrate, LaB8, which exhibits phonon-mediated superconductivity at 14 K, opening avenues for tunable electronic properties via cage atom substitution.

Contribution

It introduces a novel B-based clathrate structure, LaB8, synthesized under high pressure, demonstrating superconductivity and providing a platform for property tuning.

Findings

LaB8 has a B-rich cage with 26 B atoms encapsulating La.

LaB8 exhibits superconductivity with a transition temperature of 14 K.

The superconductivity mainly originates from electron-phonon coupling of the B cage.

Abstract

Boron-based clathrate materials, typically with three-dimensional networks of B atoms, have tunable properties through substitution of guest atoms, but the tuning of B cages themselves has not yet been developed. By combining crystal structural search with the laser-heated diamond anvil cell technique, we successfully synthesized a new B-based clathrate boride, LaB8, at ~108 GPa and ~2100 K. The novel structure has a B-richest cage, with 26 B atoms encapsulating a single La atom. LaB8 demonstrates phonon-mediated superconductivity with an estimated transition temperature of 14 K at ambient pressure, mainly originating from electron-phonon coupling of B cage. This work creates a prototype platform for subsequent investigation on tunable electronic properties through the choice of captured atoms.