Electronic structure and physical properties of early transition metal mononitrides: Density-functional theory LDA, GGA, and screened-exchange LDA FLAPW calculations

Abstract

The desirable physical properties of hardness, high temperature stability, and conductivity make the early transition metal nitrides important materials for various technological applications. To learn more about the nature of these materials, first-principles density-functional theory calculations using the full-potential linearized augmented plane wave ͑FLAPW͒ method within the local-density approximation ͑LDA͒ and with the generalized gradient approximation ͑GGA͒ have been performed. We investigate the bulk electronic and physical properties of a series of early transition metal mononitrides, namely, those formed with 3d metals ͑ScN, TiN, VN͒, 4d metals ͑YN, ZrN, NbN͒, and 5d metals ͑LaN, HfN, TaN͒ in the rocksalt structure. In particular, lattice constants, bulk moduli, heats of formation, and cohesive energies as well as bulk band structures and densities of states are reported, and trends discussed. We find that the GGA yields 1%-2% larger lattice constants, 10%-20% smaller bulk moduli, and 10%-30% lower heats of formation compared to the LDA. The GGA slightly overestimates lattice constants, but leads overall to an improved agreement with experiment compared to the LDA, for which the values are too small. These materials are metallic with the exception of ScN, YN, and LaN, which appear to be semimetals within the LDA ͑and GGA͒, but are in fact semiconductors with indirect band gaps of 1.58, 0.85, and 0.75 eV, respectively, as revealed by calculations performed using the screened-exchange LDA approach. These last, relatively unexplored, refractory III-V nitrides may therefore have potential use in device applications; in particular, ScN is well lattice matched to GaN, a wide-band-gap semiconductor that is of great current interest in relation to optoelectronic devices, and high temperature and high power electronic applications.

TBI Calculations of the Elastic Properties and Structural Phase Transformation in Novel Materials: Yttrium Nitride

“…Our calculated value of the bulk modulus as shown in Table III is 155 GPa and this value is compared to available computed data and it is closer to results of Mancera [6] calculated by first principle calculation than other data by using FLAPW and FLAPW-generalized gradient approximation (FLAPW-GGA) [8]. The study of second order elastic constants and their combinations are also important to know as they provide information about the interatomic and elastic behavior of these compounds.…”

“…They calculated their bulk properties and the Debye temperature. Some other physicists also carried out study on the electronic structure and physical properties of YN [8]. According to them this material is semimetal within the local density approximation (LDA) [15].…”

“…In the electronic industry they are important as electric contact, diffusion barriers, buffer layer etc. In the last few years there has been an increased awareness in scandium, yttrium and lanthanum nitrides due to phase transition and their semiconducting properties [4][5][6][7][8][9]. The exchange and correlation effects were treated using the generalized gradient approximation (GGA) in case of yttrium nitride (YN) by Stampfl et al [8].…”

“…The transition metal compounds MX (M denotes a transition metal element and X denotes one of the non--metallic elements C, N or O) have attracted attention during last decade because of their high hardness, high melting point, wear and corrosion resistance [1][2][3][4][5][6][7][8][9]. The investigation of the behavior of transition metal compounds under high pressure is very important because of two reasons, namely the interests in an antiferromagnetic Mott type insulator in solid state physics and their roles in the interior of the earth [2].…”

FP-LAPW investigation of electronic, magnetic, elastic and thermal properties of Fe-doped zirconium nitride

“…This compound has attracted several researchers due to their innate properties. C. Stampfl et al 4 studied the electronic and physical properties of early transition metal mono-nitrides. Yunle Gu et al 5 experimentally prepared the powdered zirconium nitride by benzene-thermal synthesis and determined the lattice constant of ZrN as 4.5675 A • .…”