First Principles Study on the Formation of Yttrium Nitride in Cubic and Hexagonal Phases

TL;DR

This study uses first principles calculations to investigate the formation and properties of yttrium nitride in cubic and hexagonal phases, revealing phase stability and electronic characteristics relevant for electronic applications.

Contribution

It provides a systematic analysis of yttrium nitride formation in different phases, highlighting phase transition behavior and electronic structure insights.

Findings

Both phases are physically achievable.

Low nitrogen allows coexistence of phases.

High nitrogen favors cubic phase by 30 kJ mol-1.

Abstract

We have studied the formation of yttrium nitride in which the Y-atoms were arranged in two common close-packed stacking: The AB-stacking (hcp-symmetry) is the ground state of metallic yttrium; while the ABC-stacking (fcc-symmetry) is the ground state of yttrium nitride. Given the different symmetries between YN and Y, there must be a phase transition (hcp->fcc) as N is incorporated in the Y-lattice. By means of first principles calculations we have made a systematical investigation where N was gradually incorporated in octahedral interstices in AB and ABC stacking of Y. We report the heat of formation, bulk modulus, lattice parameter and electronic structure of the resultant nitrides. We found that both metal arrangements are physically achievable. Furthermore, for low nitrogen incorporation the two phases may coexist. However for high nitrogen concentration the cubic phases are favored by a 30 kJ mol-1 margin. These results are important since fcc-YN is semiconducting and could be utilized as active layer in electronic devices.