Electronic and structural properties of SnO under pressure (original) (raw)
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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.
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.
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 study of SnO under high pressure
This article reports the first-principles study of SnO under high pressure within the generalized gradient approximation (GGA). We have calculated the structural, elastic, electronic and optical properties of SnO. The elastic properties such as the elastic constants Cij, bulk modulus, shear modulus, Young modulus, anisotropic factor, Pugh ratio, Poisson's ratio are calculated and analyzed. Mechanical stability of SnO at all pressure is confirmed using Born stability conditions in terms of Cij. It is also found that SnO exhibits very high anisotropy. The energy band structure and density of states are also calculated and analyzed. The results show the semiconducting and metallic properties at 0 (zero) and high pressure, respectively. Furthermore, the optical properties are also calculated. All the results are compared with those of the SnO where available but most of the results at high pressure are not compared due to unavailability of the results.
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.
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.
External pressure and composition effects on the atomic and electronic structure of SnWO4
Solar Energy Materials and Solar Cells, 2015
The atomic and electronic structure of tin tungstates, α-SnWO 4 , α-Sn 1.03 W 0.99 O 4 and β-SnWO 4 , was studied by the W L 3-edge X-ray absorption spectroscopy and first-principles linear combination of atomic orbital (LCAO) calculations based on the hybrid exchange-correlation density functional (DFT)/ Hartree-Fock (HF) scheme. It was found that the crystal structure of both α-phases is built up of strongly distorted WO 6 octahedra, whereas that of β-SnWO 4 is composed of nearly regular WO 4 tetrahedra. In addition, there are distorted SnO 6 octahedra in both αand β-phases. The metal-oxygen octahedra distortion is explained by the second-order Jahn-Teller effect. The influence of pressure on the structure of α-SnWO 4 and β-SnWO 4 was studied in detail based on the calculated equations of state. The compressibility of β-SnWO 4 was found to be larger than that of α-SnWO 4. The existence of the insulatorto-metal transition was theoretically predicted in α-SnWO 4 at about 16 GPa and was explained by a symmetrization of metal-oxygen octahedra leading to a strong interaction of Sn 5s, W 5d and O 2p states and closing of band gap.
Solid State Sciences, 2002
We have performed density functional calculations on tetragonal SnO and PbO (litharge) in the space group P4/nmm with the specific intention of examining the rôle played by Sn 5s and Pb 6s lone pairs in stabilizing the structure, and in giving rise to semi-metallic behavior (of SnO at ambient pressure and of PbO in the γ phase). Use of the electron localization function has permitted real-space visualization of the lone pair in these structures. We also discuss the electronic structure of the orthorhombic PbO (massicot, space group Pbma) which again has localized lone pairs, contrary to some earlier expectation. 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
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.
Structural and electronic properties of ZnO under high pressures
Solid State Communications, 2006
In this work, we use first-principles calculations based on density-functional theory within the local-density approximation (LDA) to investigate the structural and electronic properties of ZnO under high-pressure. We have calculated the ground-state energy, the lattice constant, the bulk modulus, and its pressure derivative of the B4 (wurtzie), B3 (zinc blende), B2 (CsCl) and B1 (rocksalt) phases of ZnO. Moreover, the electronic structure, density of states (DOS) of the B4 (wurtzite) and B1 (rocksalt) phases of ZnO have been calculated. We show that our calculated values compare acceptably well with values reported in the literature.