First-principles study of SnO under high pressure (original) (raw)
Related papers
Computational Materials Science, 2011
We investigate the structural, elastic, and electronic properties of rutile-type SnO 2 by plane-wave pseudopotential density functional theory method. The lattice constants, bulk modulus and its pressure derivative are all calculated. These properties at equilibrium phase are well consistent with the available experimental and theoretical data. Especially, we study the pressure dependence of elastic properties such as the elastic constants, elastic anisotropy, aggregate acoustic velocities and elastic Debye temperature H. It is concluded that this structure becomes more ductile with increasing pressure up to 28 GPa. Moreover, our compressional and shear wave velocities V P = 7.02 km/s and V S = 3.84 km/s, as well as elastic Debye temperature H = 563 K at 0 GPa compare favorably with the experimental values. The pressure dependences of band structures, energy gap and density of states are also investigated.
Electronic and structural properties of SnO under pressure
Physical Review B, 2005
Pressure-induced changes in the electronic and structural properties of tin monoxide are examined by means of ab initio density-functional calculations. Also, the pressure shifts of the A 1g and E g zone-center phonon modes are derived. The results are compared to recent experimental high-pressure data as well as to previous calculations for ambient conditions. In agreement with earlier findings we observe that the Sn-5s lone pair is not inert but hybridizes with the O-p states. Differences in that respect between SnO and PbO are shown to be a "relativistic dehybridization effect" caused by the large mass-velocity downshift of the Pb-6s states. SnO is a small-gap ͑indirect͒ semiconductor at ambient pressure, but an insulator-metal transition occurs as pressure is applied. The transition is estimated to occur around 5 GPa. The gap depends sensitively on the distance between the layers dE gap / d ln͑c / a͒Ϸ21 eV.
First principles studies of SnO at different structures
2010
Purpose: Structural and mechanical properties of the Sn (tin) based oxides SnO and SnO 2 are investigated. The aim of this study to determine in which structural phase SnO is found and to calculate its elastic constants at different pressures.
Structural study of SnO at high pressure
Physica B: Condensed Matter, 2006
We have studied the structural behaviour of tin monoxide (SnO) by energy dispersive X-ray diffraction (EDXRD) and EXAFS in a pressure range up to 51 GPa. We found a shear stress induced phase transition to an orthorhombically distorted structure under non hydrostatic conditions. Besides this we observed no phase transition of SnO up to the highest pressure of this study. SnO shows strong anisotropy in compression. The a-axis is rather incompressible with a linear stiffness coefficient of K a0 ¼ 306ð6Þ GPa whereas the stiffness of the c-axis is K c0 ¼ 43ð2Þ GPa. The bulk modulus of SnO is K 0 ¼ 35ð1Þ GPa and its derivative K 0 0 ¼ 6:1ð2Þ. A possible disproportionation of SnO to SnO 2 and Sn at ambient temperature under high pressure is also discussed. r
FIRST-PRINCIPLES INVESTIGATION OF SnO 2 AT HIGH PRESSURE
International Journal of Modern Physics B, 2005
The ground state properties and the structural phase transformation of tin dioxide (SnO 2 ) have been investigated using first principle full potential-linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). We used local density approximation (LDA) and the generalized gradient approximation (GGA), which are based on exchange-correlation energy optimization, to optimize the internal parameters by relaxing the atomic positions in the force directions and to calculate the total energy. For band structure calculations, we utilized both the Engel-Vosko's generalized gradient approximation (EVGGA), which optimizes the exchange-correlation potential, and also GGA. From the obtained band structures, the electron (hole) valance and conduction effective masses are deduced. For compressed volumes SnO 2 is shown to undergo two structural phase transitions with increasing pressure from the rutile-to the CaCl 2 -type phase at 12.4 GPa and to a cubic phase, space group pa3 at 22.1 GPa. The calculated total energy allowed us to investigate several structural properties, in particular, the equilibrium lattice constants, bulk modulus, cohesive energy, interatomic distances and the angles between different atomic bonds. In addition, we discuss the bonding parameter in term of charge density, which show the localization of charge around the anion side.
Computed electronic and optical properties of SnO2 under compressive stress
Optical Materials, 2014
We consider the effects of three different types of applied compressive stress on the structural, electronic and optical properties of rutile SnO 2. We use standard density functional theory (DFT) to determine the structural parameters. The effective masses and the electronic band gap, as well as their stress derivatives, are computed within both DFT and many-body perturbation theory (MBPT). The stress derivatives for the SnO 2 direct band gap are determined to be 62, 38 and 25 meV/GPa within MBPT for applied hydrostatic, biaxial and uniaxial stress, respectively. Compared to DFT, this is a clear improvement with respect to available experimental data. We also estimate the exciton binding energies and their stress coefficients and compute the absorption spectrum by solving the Bethe-Salpeter equation.
2007
Theoretical investigations concerning the high-pressure polymorphs, the equations of state, and the phase transitions of SnO 2 have been performed using density functional theory at the B3LYP level. Total energy calculations and geometry optimizations have been carried out for all phases involved, and the following sequence of structural transitions from the rutile-type (P4 2 /mnm) driven by pressure has been obtained (the transition pressure is in parentheses): f CaCl 2 -type, Pnnm (12 GPa) f R-PbO 2 -type, Pbcn (17 GPa) f pyrite-type, Pa3 h (17 GPa) f ZrO 2 -type orthorhombic phase I, Pbca (18 GPa) f fluorite-type, Fm3 hm (24 GPa) f cotunnite-type orthorhombic phase II, Pnam (33 GPa). The highest bulk modulus values, calculated by fitting pressure-volume data to the second-order Birch-Murnaghan equation of state, correspond to the cubic pyrite and the fluorite-type phases with values of 293 and 322 GPa, respectively.
Quasiparticle energies and uniaxial pressure effects on the properties of SnO2
Applied Physics Letters, 2010
We calculate the quasiparticle energy spectrum of SnO 2 within the GW approximation, properly taking into account the contribution of core levels to the energy corrections. The calculated fundamental gap is of 3.85 eV. We propose that the difference with respect to the experimental optical gap ͑3.6 eV͒ is due to excitonic effects in the latter. We further consider the effect applied on uniaxial pressure along the c-axis. Compared to GW, the effect of pressure on the quasiparticle energies and band gap is underestimated by the local-density approximation. The quasiparticle effective masses, however, appear to be well described by the latter.
Characterization of V-doped SnO2 nanoparticles at ambient and high pressures
Materials Research Express, 2018
Nanoparticles of V-doped SnO 2 with stoichiometry Sn 1−x O 2 V x (x=0.05, 0.075, 0.125) have been synthesized by a co-precipitation method. Their structural, vibrational, and nuclear properties have been characterized by x-ray Diffraction, Transmission Electron Microscopy, Energy Dispersive x-ray Spectroscopy, Raman Spectroscopy, and Mössbauer Spectroscopy (with 119 Sn probe) at ambient pressure. We also performed high-pressure synchrotron x-ray diffraction experiments. The structural behaviour was studied up to ∼10 GPa under quasi-hydrostatic conditions. It has been found that tin dioxide nanoparticles with V are more compressible than un-doped tin dioxide nanoparticles.
Effect of Pressure on the Stability and Electronic Structure of ZnO0.5S0.5 and ZnO0.5Se0.5
Journal of Electronic Materials, 2017
Structures and high-pressure phase transitions in ZnO 0.5 S 0.5 and ZnO 0.5 Se 0.5 have been investigated using density functional theory calculations. The previously proposed structures of ZnO 0.5 S 0.5 and ZnO 0.5 Se 0.5 which are chalcopyrite (I 42d), rocksalt (Fm3m), wurtzite (P6 3 mc) and CuAu-I (P 4m2) have been fully investigated. Stabilities of these materials have been systematically studied up to 40 GPa using various approaches. We have confirmed the stability of the chalcopyrite structure up to 30 GPa for which the CuAu-I structure has been previously proposed. However, our calculation revealed that CuAu-I is not a stable structure under 32 GPa and 33 GPa for both ZnO 0.5 S 0.5 and ZnO 0.5 Se 0.5 , respectively, which could explain the failure in several attempts to fabricate these materials under such conditions. We have also examined the pressure-dependence of the bandgap and electronic structure up to 30 GPa. We can conclude from our PDOS analysis that the applied pressure does not change the atomic state characters of electronic states near the top of valence and the bottom of conduction bands, but mainly modifies the dominant Zn-3d atomic state of the deep Bloch state at À1 eV below Fermi level.