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Title: Ab initio calculation of the electronic structure and spectroscopic properties of spinel {gamma}-Sn{sub 3}N{sub 4}

Abstract

The electronic structure and physical properties of {gamma}-Sn{sub 3}N{sub 4} in the spinel structure are investigated by first-principles calculations. The calculated band structure, electronic bonding, and optical properties are compared with two well-studied spinel nitrides {gamma}-Si{sub 3}N{sub 4} and {gamma}-Ge{sub 3}N{sub 4}. {gamma}-Sn{sub 3}N{sub 4} is a semiconductor with a direct band gap of 1.40 eV and an attractive small electron effective mass of 0.17. Its optical properties are different from that of {gamma}-Si{sub 3}N{sub 4} and {gamma}-Ge{sub 3}N{sub 4} because of the difference in the conduction band minimum. The Sn K, Sn L{sub 3}, Sn M{sub 5}, and N K edges of the x-ray-absorption near-edge structure spectra in {gamma}-Sn{sub 3}N{sub 4} are calculated using a supercell approach and are found to be rich in structures. These spectra are discussed in the context of the electronic structure of the unoccupied conduction band in the presence of the electron core-hole interaction. These calculated spectra can be used for the characterization of this novel compound.

Authors:
;  [1]
  1. Department of Physics, University of Missouri-Kansas City, Kansas City, Missouri 64110 (United States)
Publication Date:
OSTI Identifier:
20787853
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevB.73.045202; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; EFFECTIVE MASS; ELECTRONIC STRUCTURE; ELECTRONS; ENERGY GAP; EV RANGE; GERMANIUM NITRIDES; HOLES; OPTICAL PROPERTIES; SEMICONDUCTOR MATERIALS; SILICON NITRIDES; SPINELS; TIN NITRIDES; X RADIATION; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Ching, W. Y., and Rulis, Paul. Ab initio calculation of the electronic structure and spectroscopic properties of spinel {gamma}-Sn{sub 3}N{sub 4}. United States: N. p., 2006. Web. doi:10.1103/PHYSREVB.73.0.
Ching, W. Y., & Rulis, Paul. Ab initio calculation of the electronic structure and spectroscopic properties of spinel {gamma}-Sn{sub 3}N{sub 4}. United States. doi:10.1103/PHYSREVB.73.0.
Ching, W. Y., and Rulis, Paul. Sun . "Ab initio calculation of the electronic structure and spectroscopic properties of spinel {gamma}-Sn{sub 3}N{sub 4}". United States. doi:10.1103/PHYSREVB.73.0.
@article{osti_20787853,
title = {Ab initio calculation of the electronic structure and spectroscopic properties of spinel {gamma}-Sn{sub 3}N{sub 4}},
author = {Ching, W. Y. and Rulis, Paul},
abstractNote = {The electronic structure and physical properties of {gamma}-Sn{sub 3}N{sub 4} in the spinel structure are investigated by first-principles calculations. The calculated band structure, electronic bonding, and optical properties are compared with two well-studied spinel nitrides {gamma}-Si{sub 3}N{sub 4} and {gamma}-Ge{sub 3}N{sub 4}. {gamma}-Sn{sub 3}N{sub 4} is a semiconductor with a direct band gap of 1.40 eV and an attractive small electron effective mass of 0.17. Its optical properties are different from that of {gamma}-Si{sub 3}N{sub 4} and {gamma}-Ge{sub 3}N{sub 4} because of the difference in the conduction band minimum. The Sn K, Sn L{sub 3}, Sn M{sub 5}, and N K edges of the x-ray-absorption near-edge structure spectra in {gamma}-Sn{sub 3}N{sub 4} are calculated using a supercell approach and are found to be rich in structures. These spectra are discussed in the context of the electronic structure of the unoccupied conduction band in the presence of the electron core-hole interaction. These calculated spectra can be used for the characterization of this novel compound.},
doi = {10.1103/PHYSREVB.73.0},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 4,
volume = 73,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • The electronic and optical properties of the new cubic spinel nitrides c-Si{sub 3}N{sub 4}, c-Ge{sub 3}N{sub 4}, and that of the predicted double nitrides c-SiGe{sub 2}N{sub 4} and c-GeSi{sub 2}N{sub 4} are studied by a first-principles method. They are all semiconductors with band gaps between 1.85 and 3.45 eV and a bulk modulus between 258 and 280 GPa. From the total-energy calculations, it is shown that c-SiGe{sub 2}N{sub 4} should be a stable compound while c-GeSi{sub 2}N{sub 4} could be metastable. The compound c-SiGe{sub 2}N{sub 4} is of particular interest because of a favorable direct band gap of 1.85 eVmore » and a conduction-band effective mass of 0.49. The crystal has a very strong covalent bonding character as revealed by the calculated Mulliken effective charge and bond order. The strong covalent bonding in c-SiGe{sub 2}N{sub 4} is attributed to the optimal arrangement of the cations. The smaller Si ion occupies the tetrahedrally coordinated (8a) site and the larger Ge ion occupies the octahedrally coordinated (16d) site.« less
  • We have employed ab initio molecular dynamics to investigate the equilibrium geometries, energetics, and the nature of bonding in mixed Li-Sn clusters. Our studies reveal that a small percentage of Sn in Li-rich clusters introduces significant changes in the equilibrium geometries. It is also seen that the geometries of Sn-rich clusters are influenced by the Sn{sub 10} motif. Analysis of the nature of bonding shows that there are two competing interactions in the clusters: the polar bond between Li-Sn in the mixed clusters and Sn-Sn interaction leading to covalent bond in Sn-rich clusters.
  • Bi{sub 2}O{sub 3}-MoO{sub 3} system shows a large panoply of phases depending on Bi/Mo ratio, among them, the low temperature phases of the homologous series Bi{sub 2(n+2)}Mo{sub n}O{sub 6(n+1)} with n=3, 4, 5 and 6. They exhibit, alike most of the phases of this system, strong fluorite sub-network. Nevertheless, a multitechnique approach has been followed in order to solve the crystal structure of the n=3 member, i.e. Bi{sub 10}Mo{sub 3}O{sub 24}. From ab initio indexing X-ray powder pattern cell parameters were derived. It belongs to the monoclinic system, space group C2, with cell parameters: a=23.7282(2) A, b=5.64906(6) A, c=8.68173(9) A,more » beta=95.8668(7){sup o} with Z=2. The matrix relating this cell with the fluorite one is 4 0 1/0 1 0/-1/2 0 3/2 and a cationic localization was derived. HRTEM allowed the cationic Bi and Mo order to be modified and specified, as well as to build up a full structural ab initio model on the basis of crystal chemistry considerations. Simultaneous Rietveld refinement of multipattern X-ray and neutron powder diffraction data taking advantage of the neutron scattering length for O location have been performed. The goodness of the model was ascertained by low reliability factors, weighted R{sub b}=4.97% and R{sub f}=3.21%. This complex Bi{sub 10}Mo{sub 3}O{sub 24} structure, with 5Bi, 2Mo and 13O in different crystallographic positions of the asymmetric unit, shows good agreement between observed and calculated patterns within the data resolution. Moreover, the determination of this structure sets the basis for the crystallographic characterization of the complete family Bi{sub 2(n+2)}Mo{sub n}O{sub 6(n+1)}, whose guidelines are also evidenced in this paper. - Graphical abstract: This work reports on the ab initio determination of Bi{sub 10}Mo{sub 3}O{sub 24} structure, as well as its refinement by using the Rietveld method, from the combination of X-ray and neutron diffraction powder data. It belongs to the monoclinic system, space group C2, with cell parameters: a=23.7282(2) A, b=5.64906(6) A, c=8.68173(9) A, beta=95.8668(7){sup o} with Z=2.« less
  • Spin properties of the amino cation radicals NH/sub 3//sup +/, CH/sub 3/NH/sub 2//sup +/, (CH/sub 3/)/sub 2/NH/sup +/, and (CH/sub 3/)/sub 3/N/sup +/ have been investigated by using the ab initio UHF method with quartet annihilation and 4-31G and 6-31G/sup **/ basis sets. Hyperfine coupling tensors have been compared at optimized theoretical geometries. Experimental values and directions of the anisotropic coupling tensors are well reproduced at the UHF AA level. The difference between observed and calculated couplings appears as an indicator of the motion of the radicals in the trapping matrix.
  • The heats of formation for the boron amines BH{sub 3}NH{sub 3}, BH{sub 2}NH{sub 2}, and HBNH, tetrahedral BH{sub 4}{sup -}, and the BN molecule have been calculated by using ab initio molecular orbital theory. Coupled cluster calculations with perturbative triples (CCSD(T)) were employed for the total valence electronic energies. Correlation consistent basis sets were used, up through the augmented quadruple zeta, to extrapolate to the complete basis set limit. Core/valence, scalar relativistic, and spin-orbit corrections were included in an additive fashion to predict the atomization energies. Geometries were calculated at the CCSD(T) level up through at least aug-cc-pVTZ and frequenciesmore » were calculated at the CCSD(T)/aug-cc-pVDZ level. The heats of formation at 0K in the gas phase are {Delta}H{sub f}(BH{sub 3}NH{sub 3}) = -9.1, {Delta}H{sub f}(BH{sub 2}NH{sub 2}) = -15.9, {Delta}H{sub f}(BHNH) = 13.6, {Delta}H{sub f}(BN) = 146.4, and {Delta}H{sub f}(BH{sub 4}{sup -}) = -11.6 kcal/mol. The reported experimental value for {Delta}H{sub f}(BN) is clearly in error. The heat of formation of the salt [BH{sub 4}{sup -}NH{sub 4}{sup +}] (s) has been estimated by using an empirical expression for the lattice energy and the calculated heats of formation of the two component ions. The calculations show that both BH{sub 3}NH{sub 3}(g) and [BH{sub 4}{sup -}][NH{sub 4}{sup +}](s) can serve as good hydrogen storage systems which release H{sub 2} in a slightly exothermic process. The hydride affinity of BH{sub 3} is calculated to be 72.2 kcal/mol in excellent agreement with the experimental value at 298K of 74.2 {+-} 2.8 kcal/mol.« less