Synthesis of superfine high-entropy metal diboride powders

TL;DR

This paper reports the first successful synthesis of superfine high-entropy metal diboride powders with uniform composition and hexagonal structure using a borothermal reduction method at high temperature, supported by thermodynamic analysis.

Contribution

It introduces a novel synthesis method for high-entropy metal diboride powders and provides insights into their formation mechanisms through thermodynamic analysis.

Findings

Powders with ~310 nm particle size were synthesized.

The powders exhibited high compositional uniformity.

The formation mechanism was explained via thermodynamic analysis.

Abstract

High-purity and superfine high-entropy metal diboride powders, namely (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, were successfully synthesized via a facile borothermal reduction method at 1973 K for the first time. The as-synthesized powders with an average particle size of ~ 310 nm had a single-crystalline hexagonal structure of metal diborides and simultaneously possessed high compositional uniformity from nanoscale to microscale. In addition, their formation mechanisms were well interpreted by analyzing the thermodynamics of the possible chemical reactions based on the first principles calculations. This work will open up a new research field on the synthesis of high-entropy metal diboride powders.