First principles study on the formation of yttrium nitride in cubic and hexagonal phases

• Published in: Computational materials science 2008-03, Vol.42 (1), p.8-13
• Main Authors: Soto, G., Moreno-Armenta, M.G., Reyes-Serrato, A.
• Format: Article
• Language: English
• Subjects: Ab initio; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; DFT; Electron density of states and band structure of crystalline solids; Electron states; Exact sciences and technology; Inorganic compounds; Interstitial alloys; LAPW; Physics; Semiconductor compounds; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Transition metal nitrides; Yttrium nitride
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2007.06.003

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.