Structure and electronic properties of zirconium and hafnium nitrides and oxynitrides

Abstract

The atomic structure, stability and electronic properties of zirconium and hafnium nitrides and oxynitrides (MN, M3N4, and M2N2O; M=Zr, Hf) have been studied using first-principles density functional theory calculations. It is found that the orthorhombic Pnam structure of M3N4, which was observed experimentally for zirconium nitride, is more stable for this stoichiometry than the cubic spinel and rock-salt-type structures. The calculated band structures and electronic densities of states demonstrate that both the MN and M3N4 phases of zirconium and hafnium nitrides in the rock-salt-type structure are characterized by metallic properties, while the orthorhombic structure of the M3N4 phase exhibits an insulating behavior in agreement with experimental observations. The formation of nitrogen vacancies in the insulating M3N4 phase converts it into the metallic MN phase. Calculations of Zr2N2O and Hf2N2O in the cubic Bixbyite-type and hexagonal P3–ml crystal structures predict that these materials are insulators and that the Bixbyite-type structure found experimentally is lower in energy than the P3–ml phase.

Raman spectra and structural analysis in ZrOxNy thin films

“…The broadening of the peak at 2θ ≈ 32.2º, which would correspond to the (320) plane of the o-Zr 3 N 4 structure, could result from the small grain size and/or some reduction of the crystalline volume fraction of the coating, or even to a superposition of several peaks predicted in this region for this structure. The indexation of a particular crystalline structure to this sample is very difficult to fulfil due to the reduced number of diffraction peaks, although the available literature data suggest the formation of a structure very similar to that of Zr 3 N 4 -type, but with possible oxygen inclusions [16]. This change is also confirmed by the composition data, with the abrupt increase of the concentration of nonmetallic elements.…”

“…This second zone is what one might call a transition zone, whose diffraction patterns (very reduced and difficult to index) revealed the possibility of having the formation of poorly crystallized oxygen-doped orthorhombic, Zr 3 N 4 -type structures [6,7,[16][17][18][19].…”

Sulfur-enhanced thermoluminescence of γ-radiated zirconia

“…Full physicochemical characterization of the sulfur-modified zirconia has been described previously [17][18][19]. The table summarizes the EDS characterization of the S content of the samples prepared.…”

“…One important requirement for an ionizing radiation thermoluminescent (TL) dosimeter, however, is the need of reproducibility, linear behavior within the radiation range required for, as an example, biomedical uses, and, very relevant, the capability of controlling the TL response depending on the operation conditions of the dosimeter [15][16][17][18][19][20].…”

Spectroscopic analysis of the process‐dependent microstructure of ultra‐thin high‐k gate dielectric film systems

“…This structure is close to the fluorite-type structure of cubic HfO 2 in which one-fourth of anion positions are unoccupied and two-thirds of the remaining oxygen atoms are replaced by nitrogen atoms. 27 Given the NRA data that indicated the N dose for each sample exposed to NH 3 processing and the Hf-N bonding component in the Hf 4f spectra, the N 1s core level binding energy spectra of this sample set is of great interest. Consider the N 1s spectra measured for samples A, B, and C in Fig.…”