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1.
The present study explores the structural, elastic, electronic and optical properties of the newly synthesized monoclinic Zintl phase BaIn2P2 using a pseudopotential plane-wave method in the framework of density functional theory within the generalized gradient approximation. The calculated lattice constants and internal coordinates are in very good agreement with the experimental findings. Independent single-crystal elastic constants as well as numerical estimations of the bulk modulus, the shear modulus, Young's modulus, Poisson's ratio, Pugh's indicator of brittle/ductile behaviour and the Debye temperature for the corresponding polycrystalline phase were obtained. The elastic anisotropy of BaIn2P2 was investigated using three different indexes. The calculated electronic band structure and the total and site-projected l-decomposed densities of states reveal that this compound is a direct narrow-band-gap semiconductor. Under the influence of hydrostatic pressure, the direct D–D band gap transforms into an indirect B-D band gap at 4.08 GPa, then into a B–Γ band gap at 10.56 GPa. Optical macroscopic constants, namely, the dielectric function, refractive index, extinction coefficient, reflectivity coefficient, absorption coefficient and energy-loss function, for polarized incident radiation along the [100], [010] and [001] directions were investigated. 相似文献
2.
The structural, elastic, electronic, and optical properties of cubic spinel MgIn2S4 and CdIn2S4 compounds have been calculated using a full relativistic version of the full-potential linearized-augmented plane wave with the mixed basis FP/APW+lo method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA). Moreover, the Engel-Vosko GGA formalism is also applied to optimize the corresponding potential for band structure calculations. The ground state properties, including the lattice constants, the internal parameter, the bulk modulus, and the pressure derivative of the bulk modulus are in reasonable agreement with the available data. Using the total energy-strain technique, we have determined the full set of first-order elastic constants Cij and their pressure dependence, which have not been calculated or measured yet. The shear modulus, Young’s modulus, and Poisson’s ratio are calculated for polycrystalline XIn2S4 aggregates. The Debye temperature is estimated from the average sound velocity. Electronic band structures show a direct band gap (Г-Г) for MgIn2S4 and an indirect band gap (K-Г) for CdIn2S4. The calculated band gaps with EVGGA show a significant improvement over the GGA. The optical constants, including the dielectric function ε(ω), the refractive index n(ω), the reflectivity R(ω), and the energy loss function L(ω) were calculated for radiation up to 30 eV. 相似文献
3.
S.-L. Yang 《Journal of solid state chemistry》2009,182(4):855-3816
An alkali-metal indium phosphate crystal, K3In3P4O16, has been synthesized by a high-temperature solution reaction and exhibits a new structure in the family of the alkali-metal indium phosphates system. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group P21/n, and the following cell parameters: a=9.7003(18), b=9.8065(18), c=15.855(3) Å, β=90.346(3)°, V=1508.2(5) Å3, Z=4, R=0.0254. It possesses three-dimensional anionic frameworks with tunnels occupied by K+ cations running along the a-axis. The emission and absorption spectra of the compound have been investigated. Additionally, the calculations of energy band structure, density of states, dielectric constants and refractive indexes have been performed with the density functional theory method. Also, the two-photon absorption spectrum is simulated by two-band model. The obtained results tend to support the experimental data. 相似文献
4.
The structural, elastic, mechanical, electronic, optical properties and effective masses of CuMIIIBO2 (MIIIB = Sc, Y, La) compounds have been investigated by the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory under local density approximation. The equilibrium structural parameters are in good agreement with previous experimental and theoretical data. To our knowledge, there are no available data of elastic constants for comparison. The bulk, shear and Young's modulus, ratio of B/G, Poisson's ratio and Lamé's constants of CuMIIIBO2 have been studied. The electronic structures of CuMIIIBO2 are consistent with other calculations. The population analysis, charge densities and effective masses have been shown and analyzed. The imaginary and real parts of the dielectric function, refractive index and extinction coefficient of CuMIIIBO2 are calculated. The interband transitions to absorption of CuMIIIBO2 have been analyzed. 相似文献
5.
D.-G. Chen D.-S. Wu H. Zhang Y.-C. Zhang Y.-J. Gong Z.-G. Kan 《Journal of solid state chemistry》2004,177(11):3927-3933
A novel compound Ba2ZnV2O8 has been synthesized in high temperature solution reaction and its crystal structure has been characterized by means of single crystal X-ray diffraction analysis. It crystallizes in monoclinic system and belongs to space group P21/c with a=7.9050(16), b=16.149(3), , β=90.49(3). It builds up from 1-D branchy chains of [ZnV2O84−]∞, and the Ba2+ cations are located in the space among these chains. The IR spectrum, ultraviolet-visible diffuse reflection integral spectrum and fluorescent spectra of this compound have been investigated. The calculated results of energy band structure by the density functional theory method show that the solid-state compound of Ba2ZnV2O8 is an insulator with direct band gap of 3.48 eV. The calculated total and partial density of states indicate that the top valence bands are contributions from the mixings of O-2p, V-3d, and Zn-3d states and low conduction bands mostly originate from unoccupied antibonding states between the V-3d and O-2p states. The V-O bonds are mostly covalence characters and Zn-O bonds are mostly ionic interactions, and the ionic interaction strength is stronger between the Ba-O than between the Zn-O. The refractive index of nx, ny, and nz is estimated to be 1.7453, 1.7469, and 1.7126, respectively, at wavelength of 1060 nm for Ba2ZnV2O8 crystal. 相似文献
6.
A new quaternary lanthanide alkaline-earth tellurium(IV) oxide, La2Ba(Te3O8)(TeO3)2, has been prepared by the solid-state reaction and structurally characterized. The compound crystallizes in monoclinic space group C2/c with a=19.119(3), b=5.9923(5), c=13.2970(19) Å, β=107.646(8)°, V=1451.7(3) Å3 and Z=4. La2Ba(Te3O8)(TeO3)2 features a 3D network structure in which the cationic [La2Ba(TeO3)2]4+ layers are cross-linked by Te3O84− anions. Both band structure calculation by the DFT method and optical diffuse reflectance spectrum measurements indicate that La2Ba(Te3O8)(TeO3)2 is a wide band-gap semiconductor. 相似文献
7.
Jian-Ping Zou Sheng-Ping Guo Xiao-Ming Jiang Guang-Ning Liu Guo-Cong Guo Jin-Shun Huang 《Solid State Sciences》2009,11(9):1717-1721
A new supramolecular complex [Hg6Sb4](InBr6)Br (1) has been prepared by the solid-state reaction of HgBr2 with elemental In and Sb at 450 °C. The crystal structure of 1 features a three-dimensional [Hg6Sb4]4+ framework with cavities of two different sizes occupied by different kinds of guest anions. The bigger cavities are filled with the octahedral InBr63− ions, while the smaller cavities trap Br− ions. The optical properties were investigated in terms of the diffuse reflectance and infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is semiconductor, and the optical absorption is mainly originated from the charge transitions from Sb-5p and Br-4p to In-5s and Hg-6s states. 相似文献
8.
Jian-Ping Zou Dong-Sheng Wu Jing Zhu Jin-Shun Huang 《Journal of solid state chemistry》2007,180(3):805-811
A new quaternary supramolecular complex (Hg2As)2 (CdI4) (1) has been prepared by the solid-state reaction and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 crystallizes in the space group P21 of the monoclinic system with two formula units in a cell: a=7.945(4), b=12.934(6), c=8.094(4) Å, β=116.898°(1), V=741.7(6) Å3. The structure of 1 is characterized by a tridymite-like three-dimensional cationic framework, which is composed of mercury and arsenic atoms, with the channels being occupied by discrete CdI42− tetrahedral guest-anions. The optical properties were investigated in terms of the diffuse reflectance and Fourier transform infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is a semiconductor with a direct band gap, and that the optical absorption is mainly originated from the charge transitions from I-5p and As-4p to Cd-5s and Hg-6s states. 相似文献
9.
Two new quaternary strontium selenium(IV) and tellurium(IV) oxychlorides, namely, Sr3(SeO3)(Se2O5)Cl2 and Sr4(Te3O8)Cl4, have been prepared by solid-state reaction. Sr3(SeO3)(Se2O5)Cl2 features a three-dimensional (3D) network structure constructed from strontium(II) interconnected by Cl−, SeO32− as well as Se2O52− anions. The structure of Sr4(Te3O8)Cl4 features a 3D network in which the strontium tellurium oxide slabs are interconnected by bridging Cl− anions. The diffuse reflectance spectrum measurements and results of the electronic band structure calculations indicate that both compounds are wide band-gap semiconductors. 相似文献
10.
E. Moreira D.L. Azevedo E.W.S. Caetano V.N. Freire 《Journal of solid state chemistry》2011,184(4):921-928
Orthorhombic SrSnO3 was investigated using density functional theory (DFT) considering both the local density and generalized gradient approximations, LDA and GGA, respectively. The electronic band structure, density of states, complex dielectric function, optical absorption, and the infrared and Raman spectra were computed. Calculated lattice parameters are close to the experimental measurements, and an indirect band gap (2.27 eV) was obtained within the GGA (LDA) level of calculation. Effective masses for holes and electrons were estimated, being very anisotropic in comparison with similar results for orthorhombic CaSnO3. The complex dielectric function and the optical absorption of SrSnO3 were shown to be sensitive to the plane of polarization of the incident light. The infrared spectrum between 100 and 600 cm−1 was obtained, with its main peaks being assigned, and a nice agreement between experimental and theoretical peaks of the Raman spectrum of orthorhombic SrSnO3 was achieved. 相似文献
11.
Michael A. McGuire Andrew F. May David J. Singh Mao-Hua Du Gerald E. Jellison 《Journal of solid state chemistry》2011,184(10):2744-2750
Experimental and theoretical studies of the electronic and optical properties of orthorhombic BaCu2Se2 and BaCu2Te2 are reported. Experimental data include the electrical resistivity, Hall coefficient, Seebeck coefficient, thermal conductivity, and lattice constants for , and optical transmission and diffuse reflectance data at room temperature. Nominally stoichiometric, polycrystalline samples form with hole concentrations inferred from Hall measurements of 2×1018 and 5×1019 cm−3 near room temperature for the selenide and telluride, respectively. The corresponding mobilities are near 15 cm2 V−1 s−1 for both materials. Optical measurements reveal a transition near 1.8 eV in BaCu2Se2, while no similar feature was observed for BaCu2Te2. First principles calculations indicate both materials are direct or nearly direct gap semiconductors with calculated gaps near 1.0 eV and 1.3 eV for the telluride and selenide, respectively, and predict weak absorption below about 2 eV. Transport properties calculated from the electronic structure are also presented. 相似文献
12.
J. Zhu D.-S. Wu H. Zhang Y.-J. Gong H.-N. Tong 《Journal of solid state chemistry》2006,179(2):597-604
An alkali metal-rare earth phosphate crystal of NaLa(PO3)4 has been synthesized by high temperature solid-state reactions and structurally characterized by single crystal X-ray diffraction analysis, for the first time. It crystallizes in the monoclinic P21/n space group with lattice parameters: a=7.2655(3), b=13.1952(5), , β=90.382°(1), , Z=4. It is composed of LaO8 polyhedra and [(PO3)4]4− chains sharing oxygen atoms to form a three-dimensional framework, delimiting intersecting tunnels in which the sodium ions are located. The IR spectrum, absorption spectrum, and emission spectrum of the compound have been investigated. The absorption edge is located at 340 nm (3.60 eV). The calculated total and partial densities of states indicate that the top of valence bands is mainly built upon O-2p states which interact with P-3p states via σ (P-O) interactions, and the low conduction bands mostly originates from unoccupied La-5d states. The P-O bond is mostly covalent in character, and the ionic character of the Na-O bond is larger than that in the La-O bond. 相似文献
13.
Fu Qiang Huang 《Journal of solid state chemistry》2003,174(2):334-341
Three new compounds, Cs2Bi2ZnS5, Cs2Bi2CdS5, and Cs2Bi2MnS5, have been synthesized from the respective elements and a reactive flux Cs2S3 at 973 K. The compounds are isostructural and crystallize in a new structure type in space group Pnma of the orthorhombic system with four formula units in cells of dimensions at 153 K of a=15.763(3), b=4.0965(9), c=18.197(4) Å, V=1175.0(4) Å3 for Cs2Bi2ZnS5; a=15.817(2), b=4.1782(6), c=18.473(3) Å, V=1220.8(3) Å3 for Cs2Bi2CdS5; and a=15.830(2), b=4.1515(5), c=18.372(2) Å, V=1207.4(2) Å3 for Cs2Bi2MnS5. The structure is composed of two-dimensional ∞2[Bi2MS52−] (M=Zn, Cd, Mn) layers that stack perpendicular to the [100] axis and are separated by Cs+ cations. The layers consist of edge-sharing ∞1[Bi2S66−] and ∞1[MS34−] chains built from BiS6 octahedral and MS4 tetrahedral units. Two crystallographically unique Cs atoms are coordinated to S atoms in octahedral and monocapped trigonal prismatic environments. The structure of Cs2Bi2MS5, is related to that of Na2ZrCu2S4 and those of the AMM′Q3 materials (A=alkali metal, M=rare-earth or Group 4 element, M′= Group 11 or 12 element, Q=chalcogen). First-principles theoretical calculations indicate that Cs2Bi2ZnS5 and Cs2Bi2CdS5 are semiconductors with indirect band gaps of 1.85 and 1.75 eV, respectively. The experimental band gap for Cs2Bi2CdS5 is ≈1.7 eV, as derived from its optical absorption spectrum. 相似文献
14.
15.
The electronic structures of three wurtzite type isostructural compounds LiBSe2 (B=Al, Ga, In) are studied by the density functional theory (DFT). The results reveal that the presence of Li cations has direct influence on neither the band gaps (Eg) nor the bonding levels, but plays an important role in the stabilization of the structures. The band structures and densities of states (DOS) are analyzed in detail, and the band gaps of LiBSe2 adhere to the following trend Eg(LiAlSe2)>Eg(LiGaSe2)>Eg(LiInSe2), which is in agreement with the decrease of the bond energy of the corresponding Se 4p-B s antibonding orbitals. The role of the active s electrons of B element on the band gaps is also discussed. Finally, the optical properties are predicted, and the results would be a guide to understand the experiments. 相似文献
16.
The new vanadate BiMgVO5 has been prepared and its structure has been determined by single crystal X-ray diffraction: space group P21/n, , , , β=107.38(5)°, wR2=0.0447, R=0.0255. The structure consists of [Mg2O10] and [Bi2O10] dimers sharing their corners with [VO4] tetrahedra. The ranges of bond lengths are 2.129-2.814 Å for Bi-O; 2.035-2.167 Å for Mg-O and 1.684-1.745 Å for V-O. V-O bond lengths determined from Raman band wavenumbers are between 1.679 and 1.747 Å. An emission band overlapping the entire visible region with a maximum around 650 nm is observed. 相似文献
17.
M. Fang H. Zhang D. Zhao W.-L. Zhang S.-L. Yang 《Journal of solid state chemistry》2008,181(9):2165-2170
A sodium gadolinium phosphate crystal, Na3GdP2O8, has been synthesized by a high-temperature solution reaction, and it exhibits a new structural family of the alkali-metal-rare-earth phosphate system. Although many compounds with formula M3LnP2O8 have been reported, but they were shown to be orthorhombic [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] rather than monoclinic as shown in this paper. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group C2/c and the cell parameters: a=27.55 (25), b=5.312 (4), c=13.935(11) Å, β=91.30(1)°, and V=2038.80 Å3, Z=4. Its structure features a three-dimensional GdP2O83− anionic framework with two different types of interesting tunnels at where Na atoms are located by different manners. The framework is constructed by Gd polyhedra and isolated PO4 tetrahedra. It is different from the structure of K3NdP2O8 [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] with space group P21/m that shows only one type of tunnel. The emission spectrum and the absorption spectrum of the compound have been investigated. Additionally, the calculations of band structure, density of states, dielectric constants, and refractive indexes have been also performed with the density functional theory method. The obtained results tend to support the experimental data. 相似文献
18.
T. V. Narasaiah R. N. P. Choudhary N. C. Shivaprakash 《Journal of Chemical Sciences》1988,100(5):447-453
Structural (at room temperature) and dielectric and thermal properties of TlH2AsO4 have been studied as functions of temperature to understand the existence of its reported phase transition. The space group
and cell parameters of the compound were determined. The crystal structure was determined by Patterson and Fourier difference
methods and refined by the full-matrix least-squares technique. The structure can be explained in terms of zig-zag chains
of H-bonds running along thec-axis. Careful studies on dielectric and thermal properties of the substance do not suggest any ferroelectric phase transitions
in it. 相似文献
19.