Electronic band structure and carrier effective mass in calcium aluminates

TL;DR

This study uses first-principles calculations to analyze the electronic band structure and effective masses in calcium aluminates and related oxides, revealing consistent electron mobility potential across different compositions.

Contribution

It provides detailed insights into the conduction band structure and effective masses in calcium aluminates, highlighting their potential for doping applications.

Findings

Conduction band formed from oxygen antibonding p-states.

Effective masses are nearly isotropic and similar across compounds.

Effective mass insensitivity suggests good doping potential.

Abstract

First-principles electronic band structure investigations of five compounds of the CaO-Al2O3 family, 3CaO.Al2O3, 12CaO.7Al2O3, CaO.Al2O3, CaO.2Al2O3 and CaO.6Al2O3, as well as CaO and alpha-, theta- and kappa-Al2O3 are performed. We find that the conduction band in the complex oxides is formed from the oxygen antibonding p-states and, although the band gap in Al2O3 is almost twice larger than in CaO, the s-states of both cations. Such a hybrid nature of the conduction band leads to isotropic electron effective masses which are nearly the same for all compounds investigated. This insensitivity of the effective mass to variations in the composition and structure suggests that upon a proper degenerate doping, both amorphous and crystalline phases of the materials will possess mobile extra electrons.