Effect of metal vacancies on the electronic band structure of hexagonal Nb, Zr and Y diborides

TL;DR

This study investigates how metal vacancies influence the electronic band structures of hexagonal Nb, Zr, and Y diborides, revealing variations in density of states near the Fermi level that may relate to superconductivity discrepancies.

Contribution

It provides detailed calculations of energy band structures for metal-deficient diborides and analyzes the impact of vacancies on their electronic properties.

Findings

Metal vacancies alter the density of states near the Fermi level.

The effects of vacancies differ among Nb, Zr, and Y diborides.

Vacancy formation energies are estimated and discussed.

Abstract

Energy band structures of metal-deficient hexagonal diborides M$_{0.75}$B$_2$ (M = Nb, Zr and Y) were calculated using the full-potential LMTO method. The metal vacancies change the density of states near the Fermi level and this effect is quite different for III-V group transition metal diborides. Contradictory data on superconductivity in diborides may be supposed to be connected with nonstoichiometry of samples. Vacancy formation energies are estimated and analyzed.