Structural stabilities and band structure characteristics of platinum nitride (PtN) via first-principles calculations (original) (raw)
Related papers
Structures and electronic properties of platinum nitride by density functional theory
Physical Review B, 2005
We present the results of ground state electronic structure calculations of the zinc-blende and rocksalt phases of binary platinum nitride ͑PtN͒ using density functional theory. Several exchange-correlation functionals including the local spin density approximations, generalized gradient approximations ͑GGA͒, a nonempirical meta-GGA, and a screened Coulomb hybrid functional have been employed. We use Gaussian type orbitals within the framework of periodic boundary conditions. Our results confirm earlier findings, in that the zincblende structure of PtN is energetically more stable than the rocksalt structure. The predicted energy difference between the two phases is rather small with the more elaborate functionals. Both phases are predicted to be metallic and extended Pt d-N p hybridizations are found in both of them. We have also calculated the phase transition pressure between both phases. The bulk modulus of the zinc-blend phase of PtN is significantly higher than that of bulk platinum.
We report an ab initio study of the mechanical stability of platinum nitride (PtN), in four different crystal structures, the rock salt (rs-PtN), zinc blende (zb-PtN), cooperite and a face centered orthorhombic phase. Only the rs-PtN phase is found to be stable and has the highest bulk modulus B = 284 GPa. Its electronic density of states shows no band gap making it metallic. The zb-PtN phase does not stabilize or harden by the nitrogen vacancies investigated in this study. Therefore, the experimental observation of super hardness in PtN remains a puzzle.
Mechanical stability of possible structures of PtN investigated using first-principles calculations
Physical Review B, 2006
We report an ab initio study of the mechanical stability of platinum nitride ͑PtN͒, in four different crystal structures, the rock salt ͑rs-PtN͒, zinc-blende ͑zb-PtN͒, cooperite, and a face-centered orthorhombic phase. Of these phases only the rs-PtN phase is found to be stable and has the highest bulk modulus B = 284 GPa. Its electronic density of states shows no band gap making it metallic. The zb-PtN phase does not stabilize or harden by the nitrogen vacancies investigated in this study. Therefore, the experimental observation of super hardness in PtN remains a puzzle.
FP-LMTO investigations of mechanical stability and high pressure of platinum nitride compounds
Solid State Communications, 2009
We report local density functional calculations using the full potential linear muffin-tin orbital (FP-LMTO) method for binary platinum nitride (PtN), in five different crystal structures, the rock salt (B1), zinc-blende (B3), wurtzite (B4), nickel arsenide (B8), and PbS (B10) phases. The ground state properties such as the equilibrium lattice constant, elastic constants, the bulk modulus and its pressure derivative of PtN in these phases are determined and compared with the other available experimental and theoretical works.
Materials Chemistry and Physics, 2011
A comprehensive first principles study of structural, elastic, electronic, phonon and thermodynamical properties of novel metal carbide, platinum carbide (PtC) is reported within the density functional theory scheme. The ground state properties such as lattice constant, elastic constants, bulk modulus, shear modulus and finally the enthalpy of PtC in zinc blende (ZB) and rock-salt (RS) structures are determined. The energy band structure and electron density of states for the two phases of PtC are also presented. Of these phases zinc blende phase of PtC is found stable and phase transition from ZB to RS structure occurs at the pressure of about 37.58 GPa. The phonon dispersion curves and phonon DOS are also presented. All positive phonon modes in phonon dispersion curves of ZB-PtC phase indicate a stable phase for this structure. Within the GGA and harmonic approximation, thermodynamical properties are also investigated. All results reveal that the synthesized PtC would favor ZB phase. The compound is stiffer and ductile in nature.
Theoretical study of ground state and high-pressure phase of platinum carbide
Journal of Physics and Chemistry of Solids, 2008
We report local density-functional calculations using the full-potential linearized muffin-tin orbital method (FP-LMTO) for platinum carbide (PtC) in the, rock-salt (B1), zinc-blende (B3), wurtzite (B4), nickel-arsenide (B8) and PbO (B10) structures. The ground state properties such as the equilibrium lattice constant, elastic constants, the bulk modulus and its pressure derivative of PtC in these phases are determined and compared with available experimental and theoretical data.
2013
We present a detailed quantum mechanical non empirical DFT investigation of the energyoptimized geometries, phase stabilities and electronic properties of bulk Pt3N, PtN and PtN2 in a set of twenty different crystal structures. Structural preferences for these three stoichiometries were analyzed and equilibrium structural parameters were determined. We carefully investigated the band-structure and density of states of the relatively most stable phases. Further, GW0 calculations within the random-phase approximation (RPA) to the dielectric tensor were carried out to derive their frequency-dependent optical constants of the most likely candidates for the true crystal structure. Obtained results were comprehensively compared to previous calculations and to experimental data. CONTENTS I. Introduction 1 II. Calculation Methods 2 A. Stoichiometries and Crystal Structures 2 B. Electronic Relaxation Details 2 C. Geometry Optimization and EOS 3 D. Formation Energy 3 E. GWA Calculations and Optical Properties 3 III. Results and Discussion 4 A. EOS and Relative Stabilities 7 B. Volume per Atom and Lattice Parameters 8 C. Bulk Modulus and its Pressure Derivative 8 D. Formation Energies 9 E. Electronic Properties 9 F. Optical Properties 11 G. PtN versus PtN 2 11 IV. Conclusions 13 Acknowledgments 13 References 13
Journal of Alloys and Compounds, 2009
We present the results of a theoretical study of the structural and optoelectronic properties of PtN 2 , using the full-potential linearized muffin-tin orbital method (FP-LMTO). In this approach, the local density approximation (LDA) is used for the exchange correlation potential. The calculated total energy allowed us to investigate several structural properties in particular the lattice constant, bulk modulus, pressure derivative of bulk modulus. The phase stability was determined from total energy calculations for both the pyrite (C2) and fluorite (C1) phases. A numerical first-principles calculation of the elastic constants was used to calculate C 11 , C 12 and C 44. We estimated the Debye temperature of PtN 2 from the average sound velocity. Band structure, density of states, band gap pressure coefficients and effective masses are also given. On the other hand, an accurate calculation of linear optical functions (the dielectric function, refraction index and reflectivity R(ω)) is performed in the photon energy range up to 13.5 eV. The results obtained are compared with other calculations and experimental measurements.
The first principles study on PtC compound
Materials Chemistry and Physics, 2008
ABSTRACT We have studied structural, thermodynamic, elastic, and electronic properties of platinum carbide (PtC) in zinc-blende and rock-salt structures by performing ab initio calculations within the LDA approximations. Particularly, we have focused on the structural and the pressure dependence of elastic moduli and related quantities. The other basic key properties, such as the lattice constant, cohesive energy, the phase transition pressure, bulk modulus and its pressure derivative are also repeated and compared with the other available experimental and theoretical works.
Physical Review B, 2009
In many theoretical studies of the properties of solids, the first and often crucial step entails the determination of the crystal structure via some form of energy minimization. Here we discuss general potential pitfalls that are often encountered in such calculations. We do so in the context of the classic zinc-blende crystal structure that underlines all octet semiconductors and was more recently invoked to explain nonoctet halfmetallic magnets such as CrAs, as well as noble-metal nitrides such as PtN, PdN, and NiN. These pitfalls are related to the way in which mechanical instabilities of assumed structures are identified, discarded, and replaced. Using a more general global space-group optimization ͑GSGO͒ approach uncovers different and more complex structures that have much lower energies and do not have mechanical instabilities.