Bond distances and chain angle of hexagonal selenium at high pressure

McCann, D. R.; Cartz, L.

doi:10.1063/1.1660946

Cited by 58 publications

(18 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The experimental lattice parameters of bulk selenium in a hexagonal unit cell under standard temperature and pressure conditions are a = b = 4.366-4.368Å, and c = 4.955-4.958Å. 53,56,57 The lattice parameters for bulk tellurium are a = b = 4.451Å, and c = 5.926Å. 53 In Fig.…”

Section: Resultsmentioning

confidence: 99%

Exfoliation energy, quasiparticle band structure, and excitonic properties of selenium and tellurium atomic chains

et al. 2018

View full text Add to dashboard Cite

Effects that are not captured by the generalized-gradient density-functional theory play a prominent effect on the structural binding, and on the electronic and optical properties of reduceddimensional and weakly-bound materials. Here, we report the exfoliation energy of selenium and tellurium atomic chains with non-empirical van der Waals corrections, and their electronic and optical properties with the GW and Bethe-Salpeter formalisms. The exfoliation energy is found to be within 0.547 to 0.719 eV/u.c. for the selenium atomic chain, and 0.737 to 0.926 eV/u.c. for the tellurium atomic chain (u.c. stands for unit cell), depending on the approximation for the van der Waals interaction and the numerical tool chosen. The GW electronic bandgap turned out to be 5. 22-5.47 (4.44-4.59) eV for the Se (Te) atomic chains, with the lowest bound obtained with the Godby-Needs (GB), and the upper bound to the Hybertsen-Louie (HL) plasmon-pole models (PPMs). The binding energy of the ground-state excitonic state ranges between 2.69 to 2.72 eV for selenium chains within the HL and GB PPM, respectively, and turned out to be 2.35 eV for tellurium chains with both approximations. The ground state excitonic wave function is localized within 50Å along the axis for both types of atomic chains, and its energy lies within the visible spectrum: blue [2.50(GN)-2.78(HL) eV] for selenium, and yellow-green [2.09(GN)-2.28(HL) eV] for tellurium, which could be useful for LED applications in the visible spectrum.

show abstract

Section: Resultsmentioning

confidence: 99%

Exfoliation energy, quasiparticle band structure, and excitonic properties of selenium and tellurium atomic chains

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The phase and crystallographic structure of the nanocrystals were characterized using grazing incidence X-ray diffraction (GIXRD) patterns, which were recorded using a Bruker D8 Advance with a fixed θ of 0.5°, scanning rate of 0.2°min −1 , step size of 0.02°, and 2θ range from 10 to 80°, using CuK α radiation (λ ave = 1.54 Å) operating at 40 kV and 40 mA. The starting Rietveld refinement model used CuSe, 46 Se, 47 CuInSe 2 , 48 CuGaSe 2 , 49 and CuIn 0.52 Ga 0.48 Se 2 . 50 The fundamental parameters peak-shape profile was used; a fivecoefficient Chebychev polynomial and 1/x background, zero error, scale factors, unit cell parameters, and crystal size were sequentially refined using the TOPAS V4 program.…”

Section: Methodsmentioning

confidence: 99%

Evolution Pathway of CIGSe Nanocrystals for Solar Cell Applications

Ahmadi¹,

Pramana²,

Xi³

et al. 2012

J. Phys. Chem. C

View full text Add to dashboard Cite

CuIn x Ga 1−x Se 2 nanocrystals synthesized via the hot injection route have been used to make thin film solar cells with high power conversion efficiency. Thus, CuIn x Ga 1−x Se 2 nanocrystals have the potential to provide a low cost and high efficiency solution to harvest solar energy. Stoichiometry control of these nanocrystals offers the possibility of tuning the band gap of this material. It is important to understand how the composition of quaternary CuIn x Ga 1−x Se 2 nanocrystals evolves to control the stoichiometry of this compound. We report a systematic study of the growth and evolution pathways of quaternary CuIn 0.5 Ga 0.5 Se 2 nanocrystals in a hot coordination solvent. The reaction starts by the formation of a mixture of binary and ternary nanocrystals, which transforms subsequently to CuIn 0.5 Ga 0.5 Se 2 nanocrystals. These binary and ternary compounds dissolve in the course of the reaction, so as to provide the molecular precursor for monophasic CuIn 0.5 Ga 0.5 Se 2 nanocrystals to form. Here, we study the growth sequence of these spherical, monophasic CuIn 0.5 Ga 0.5 Se 2 nanocrystals as a function of time. Control experiments indicated that the phase changes of CuIn 0.5 Ga 0.5 Se 2 nanocrystals are temperature-and time-dependent. The change in the stoichiometry of CuIn 0.5 Ga 0.5 Se 2 during growth was estimated using Vegard's law.

show abstract

“…5 Assuming that a h and a t are pressure independent, and knowing how the lattice constants and atomic position parameters change with hydrostatic pressure, 14 we have also calculated (AR/RAP) ± and (AR/RAP)\\. The values a x = 10.2± 0.2 A 3 and a h = 3.23 ± 0.06 A 3 predict e ± = 7.0± 0.5, £|,= 12.0± 1.5, (AR/RAP) ± = (1.8±0.2)xl0" 5 /bar, and (AR/RAP) U = (1.3± 0.2) xl0~5/bar, all within experimental error.…”

Section: £ S £L®m + Qp)-mentioning

confidence: 99%

Pressure Dependence of Reflectivity of Se: Experimental Evidence for Large Local-Field Corrections

Kastner

Forberg

1976

Phys. Rev. Lett.

View full text Add to dashboard Cite

Spectroscopic theories of chemical bonding in solids have proved to be powerful for predicting a wide range of properties of the A N B 8~N crystals (Ge, GaAs, etc.). The starting point of these theories is the identification of the bond strength with a spectroscopically determined energy. In Phillips's theory 1 this energy is determined by the dielectric constant, in Harrison's 2 theory it is the energy of the E 2 peak in the imaginary part of the dielectric function. In the case of the cova-lent^-B 8 "^ crystals, it may be reasonable to assume that microscopic fields and the modification of matrix elements resulting from exchange are small. (All of these effects will be called "localfield corrections" in this Letter. 3 ) In such solids the charge density is fairly uniformly distributed around the atoms. On the other hand, in very ionic or molecular solids the charge density may be quite localized. In this case the determination of the bond strength from the spectroscopic energy is strongly modified by local-field corrections. 4 Therefore, in order that spectroscopic theories of bonding can be extended to ionic and Phys. Rev. B(to be published). molecular materials, local-field corrections must be better understood. This Letter presents the results of a new technique for studying localfield corrections in solids. Since local-field corrections are density dependent, the pressure dependence of the optical properties of solids can indicate the size of these effects if the electrons' energy states are not strongly density dependent. For example, measurements of the pressure coefficient of the infrared refractive index for amorphous alloys containing Ge and Se show that Se-rich alloys obey the Lorenz-Lorentz relation, 5 indicating large local-field effects in these materials. The pressure dependence of the reflectivity will reveal more information about local-field corrections, and since for Se these corrections are expected to be large, Se is an ideal material for study.Early measurements of the reflectivity as a function of pressure were limited to observing energy shifts of the reflectivity peaks. 6 Measuring the variation of the magnitude of the reflectivity is difficult because the refractive indices The pressure dependence of the reflectivity of trigonal and amorphous Se has been measured between 1.1 and 4.5 eV using a new technique. The results indicate that localfield corrections are large. Structure near 2 eV suggests a localized excitation in both the amorphous and the crystalline material. 740

show abstract

Bond distances and chain angle of hexagonal selenium at high pressure

Cited by 58 publications

References 12 publications

Exfoliation energy, quasiparticle band structure, and excitonic properties of selenium and tellurium atomic chains

Exfoliation energy, quasiparticle band structure, and excitonic properties of selenium and tellurium atomic chains

Evolution Pathway of CIGSe Nanocrystals for Solar Cell Applications

Pressure Dependence of Reflectivity of Se: Experimental Evidence for Large Local-Field Corrections

Contact Info

Product

Resources

About