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1.
B. Sankar B. Natarajan S. Mithira H. Anandhalakshmi P. Sambasiva Rao 《Crystal Research and Technology》2007,42(2):173-179
Single crystal electron paramagnetic resonance studies on magnesium rubidium sulphate hexahydrate doped with Mn(II) impurity, in the form of 0.1% of manganous chloride, are carried out at room temperature. The angular variation spectra of the crystal in the three orthogonal planes show that the paramagnetic impurity Mn(II) has entered the host lattice interstitially. The spin Hamiltonian parameters calculated are: gxx = 1.974, gyy = 1.928, gzz = 1.980; Axx = 9.28, Ayy = 8.58, Azz = 9.87 mT and Dxx = ‐18.71, Dyy = ‐5.59, Dzz = 24.30 mT. The room temperature and liquid nitrogen temperature study for polycrystalline sample indicate no phase transition. The percentage covalency of Mn–O bond has been estimated to be 11. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
P. N. Selvakumar B. Natarajan P. Sambasiva Rao P. Subramanian 《Crystal Research and Technology》2008,43(8):857-862
In order to rationalize the low hyperfine value for the parallel component of copper nucleus, another system with lithium as host has been investigated using Electron Paramagnetic Resonance (EPR) technique. Single crystal EPR studies have been carried out at 300 K on Cu(II) doped glycine lithium sulphate system. Angular variation of hyperfine structure lines in the three orthogonal planes show the presence of two sites which are magnetically inequivalent but chemically equivalent with g and A values as: gxx = 2.084, gyy = 2.057, gzz = 2.311 and Axx = 8.96 mT, Ayy = 3.26 mT, Azz = 15.95 mT respectively. The impurity entered the lattice interstitially. The admixture and molecular coefficients are evaluated by collaborating EPR data with optical data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
3.
In order to understand the effect of charge compensating vacancies on the number, orientation and magnitude of D‐tensors, single crystal EPR measurements have been carried out with Cr(III) in zinc(II) potassium phosphate hexahydrate at room temperature. During crystal rotations, a maximum of 6/7 resonance lines or a minimum of 2 is noticed. Crystal rotations done in the three orthogonal planes have yielded spin Hamiltonian parameters for one site with: gxx=1.969, gyy= 1.995, gzz= 2.107; Dxx= 66.2 mT; Dyy= 91.7 mT, and Dzz=‐157.9 mT. The powder EPR spectrum indicates a very broad line at g = 8, without any extra resonances from 0 to 650 mT both at room temperature and 77 K. The reason may be that due to large zero field splitting, the resonance at g = 2 is shifted to g = 8 position and the other resonances are below 0 or above 650 mT. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
K. Velavan R. V. S. S. N. Ravikumar R. Venkatesan P. Sambasiva Rao 《Crystal Research and Technology》2004,39(5):448-453
The optical absorption spectra of Ni(II) doped hexaimidazole zinc(II) dichloride tetrahydrate (HZDT) and Cu(II) doped magnesium potassium phosphate hexahydrate (MPPH) have been studied at room temperature. Ni(II)/HZDT spectrum consists of three strong and one weak band. The calculated value of Dq is 1051 cm‐1 and the interelectron repulsion parameters B and C are 854 and 3626 cm‐1 respectively. The correlation of optical work with EPR has yielded the spin‐orbit interaction parameters λ and ξ as –225 and –450 cm‐1 respectively. The symmetry around the Ni(II) ion is distorted octahedral, as suggested by EPR results. The estimated percentage covalency of the nickel‐nitrogen bond is around 30%. The optical absorption studies of Cu(II)/MPPH show three bands, which are identified as 2B1g → 2A1g, 2B1g → 2B2g and 2B1g → 2Eg transitions. The octahedral field parameter Dq and the tetragonal field parameters have been evaluated from the observed adsorption bands. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
V. I. Rozhdestvina A. V. Ivanov M. A. Zaremba O. N. Antsutkin W. Forsling 《Crystallography Reports》2008,53(3):391-397
Single-crystalline cooperite (PtS) with a nearly stoichiometric composition was characterized in detail by X-ray diffraction, electron-probe X-ray microanalysis, and high-resolution scanning electron microscopy. For the first time it was demonstrated that 195Pt static and MAS NMR spectroscopy can be used for studying natural platinum minerals. The 195Pt chemical-shift tensor of cooperite was found to be consistent with the axial symmetry and is characterized by the following principal values: δ xx = ?5920 ppm, δ yy = ?3734 ppm, δ zz = +4023 ppm, and δiso = ?1850 ppm. According to the ESR data, the samples of cooperite contain copper(II), which is adsorbed on the surface during the layer-by-layer crystal growth and is not involved in the crystal lattice. 相似文献
6.
Optical absorption and EPR spectra of Li2SO4 · H2O crystals doped with Cr3+ are studied at liquid nitrogen temperature. The bands are found in absorption spectra with maxima about 17000, 23 800 and 37 200 cm−1, assigned to the 4A2 → 4T2, 4A2 → 4T1 and 4A2 → 4T1 (4P) transitions, respectively. The crystal field theory parameters were determined and appeared to be as follows: Dq = 1700 cm−1, B = 667 cm−1, C = 3002 cm−1. The lines resulting from Cr3+ ions are found in EPR spectra. All lines are doublets, which is indicative of presence of two magnetically unequivalent centre positions, and have the hyperfine structure resulting from interaction of the unpaired electron spin with Cr53 isotope nucleus. Centres are oriented in such a way, that z-axes, corresponding to two centre positions, are situated at both sides of a-axis at an angle of about 3°. Spin Hamiltonian parameters were found as follows: gx = 1.985, gy = 1.984, gz = 1.988, D = 0.130 cm−1, E = 0.016 cm−1, |A| = 17.8 · 10−4 cm−1. 相似文献
7.
G. F. Kuznetsov 《Crystallography Reports》2000,45(2):294-299
Plastic deformation in a single-crystal layer of the In0.12Ga0.88As/(111)InP solid solution is identified by the methods of X-ray diffractometry (XRD) and the double-crystal pseudorocking
curves (DCPRC). X-ray topographs showed the generation of three intersecting systems of straight dislocations in the layer.
In a one-layer ZnSe/GaAs structure and multilayer ZnSe/ZnSe1 − x
Sx/ZnSe/GaAs structures, the elastic and plastic strains were detected by the combined XRD-DCPRC method. The major components
of the thermoelastic and plastic-deformation tensors were determined as εxx = εyy = 3.5 × 10−3 and εzz = 2.35 × 10−3. Using these data, the dislocation densities were determined as N
d
∼ 2.5 × 108 cm−2 and N
d
∼ 3 × 1010 cm−2 for the 7 μm-thick ZnSe and 1 μm-thick InAs layers, respectively. In a superlattice of the AlxGa1 − x
As/GaAs/⋯/GaAs-type with a large lattice parameter, the plastic deformation was detected. X-ray topography confirmed that
the dislocation density in this superlattice equals ∼105 cm−2.
__________
Translated from Kristallografiya, Vol. 45, No. 2, 2000, pp. 326–331.
Original Russian Text Copyright ? 2000 by Kuznetsov. 相似文献
8.
Jerry P. Jasinski Heidi E. Exel Alfonso Castiñeiras Elena Bermejo Heloisa Beraldo Douglas X. West 《Journal of chemical crystallography》2003,33(1):11-18
The crystal and molecular structure of copper(II) complexes of benzil bis(3-piperidylthiosemicarbazone), [Cu(Bnzpip)] and 1-phenylpropane-1,2-dione bis(3-piperidylthiosemicarbazone), [Cu(Pmpip)] have been determined. [Cu(Bnzpip)] is monoclinic, space group P21/n with a = 13.9375(10) Å, b = 11.6621(4) Å, c = 16.4710(10) Å, = 100.667(2)°, and V = 2630.9(3) Å3 with Z = 4, for d
calc = 1.399 g/cm3. [Cu(Pmpip)] is also monoclinic, space group P21/n with a = 11.292(6) Å, b = 10.219(5) Å, c = 20.292(6) Å, = 101.50(3)°, and V = 2295(2) Å3 with Z = 4, for d
calc = 1.525 g/cm3. Both complexes involve N2S2 coordination, are relatively planar except for the phenyl rings and have similar bond distances and angles to copper(II) complexes of other 3-piperidylthiosemicarbazones. 相似文献
9.
EPR spectra are studied of X-irradiated sodium dichromate crystals grown from an aqueous solution by evaporation at 31°C. Doublet lines of EPR-absorption are attributed to the Cr5+ ions in the CrO43− and CrO3− radicals resulting from radiation decomposition of Cr2O72− and being in the lattice in two unequivalent positions. Hyperfine structure caused by interaction of an unpaired electron with Cr53 nucleus were observed both at liquid nitrogen and room temperatures. For the line, caused by CrO43− radical, gy and Ay directions coincide and angles both between Ax, gx and Az, gz make up ∼ 25°. The spectrum is described by usual spin Hamiltonian for S = 1/2 with following parameters (T = 77 K): for CrO: gz = 1.984, gy = 1.970, gx = 1.961, |Az| = 8.2 · 10−4 cm−1, |Ay| = 13.7 × 10−4 cm−1, |Ax| = 36.1 · 10−4 cm−1; for CrO3−: gz = 1.915, gy = 1.975, gx = 1.985, |Az| = 32.2 · 10−4 cm−1. 相似文献
10.
A. B. Vassilikou-Dova 《Crystal Research and Technology》1991,26(1):135-138
In single crystals of scapolite from two different localities, three paramagnetic centres are detected by electron paramagnetic resonance (EPR): 1. One isotropic singlet with giso = 2.005; 2. One triclinic singlet with g‖ = 2.005 ± 0.001 and g⟂= 2.009; 3. One triclinic sextet with g‖= 2.005 ± 0.001, g⟂ = 2.011; A‖ = 85.4 × 10−4 cm−4, A⟂ = 85.3 × 10−4 cm−1. Centres 1 and 2 can be attributed to colour centres as they are bleached after annealing. Centre 3 can be due to Mn2+ (only the central Ms = ± 1/2 transition is observable) most likely substituting for Ca2+ The site symmetry must be triclinic but due to Al, Si disorder and mixed Na, Ca composition the different components from magnetically non-equivalent sites are averaged out for many orientations. 相似文献
11.
Yun‐Ming Sun Feng‐Ying Dong Jian‐Min Dou Da‐Cheng Li Xi‐Ke Gao Da‐Qi Wang 《Crystal Research and Technology》2008,43(2):218-222
One metalorganic complex [K(cis‐syn‐cis‐ dicyclohexyl‐18‐crown‐6)]2[Cu(mnt)2] (mnt = maleonitriledithiolate) has been obtained by the reaction of dicyclohexyl‐18‐crown‐6 with K2mnt and CuCl2·2H2O. The title complex has been characterized by elementary analysis, FT‐IR, UV‐Vis spectroscopy and x‐ray single crystal diffraction. The title complex crystallizes in the triclinic space group P1 with crystallographic data: a = 10.870(6) Å, b = 11.536(6) Å, c = 12.904(7) Å, α = 101.541(10)°, β = 110.573(9)°, γ = 99.441(9)°, V = 1435.2(13) Å3, Z = 1, Dcalcd = 1.350 g/cm3, F(000) = 615, R1 = 0.0641, wR2 = 0.1475. It displays one‐dimensional chain‐like structure formed by [K(cis‐syn‐cis‐ dicyclohexyl‐18‐crown‐6)]+ complex cations and [Cu(mnt)2]2‐ complex anions through N‐K‐N interactions. Its electrochemical behavior has also been studied by the cyclic voltammetry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
R. Ramasubramanian S. Kumaresan R. Thomas A. David Stephen P. Kumaradhas 《Crystal Research and Technology》2007,42(10):1024-1028
Pyridine‐2‐(3′‐mercaptopropanoic acid)‐N ‐oxide (I), is a higher homologue of 1‐oxopyridinium‐2‐thioacetic acid (II) [1]. It crystallizes in monoclinic space group P21 with a = 9.2168(2) Å, b = 4.1423(2) Å, c = 11.3904(4) Å, β = 98.65(2)°, V = 429.93(3) Å3 and Z = 2. The least‐squares refinement gave residual index R = 0.024 for 1070 observed reflections. The introduction of an additional methylene group in (II) causes a flip in the carboxylic acid group of (I) that facilitates the molecules to align infinite antiparallel chains through strong C–H···O interactions. The molecules are interlinked by O–H···O hydrogen bonding across the chains and forming an infinite screw chain along y‐direction. The molecular packing is stabilized by O–H···O and C–H···O hydrogen bonding and π‐π electron interactions. This is an important facet of the crystal packing. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
The structure of the title complexes [Cu(AFO)2(H2O)2](ClO4)2.2(AFO).2H2O (AFO = 4,5‐Diazafluoren‐9‐one)has been established by single‐crystal X‐ray diffraction. The complex crystallizes in the triclinic space group P‐1 with cell constants a = 7.659(3) Å, b = 11.066(3) Å, c = 14.203(5) Å, alpha = 75.16(3)°, β = 79.87(3)°, gamma = 85.71(3)°, Z = 1. The structure was solved by direct methods and refined to R1 = 0.0595 (wR2 = 0.1164). The X‐ray analysis reveals that a pair of AFO ligands chelate to a Cu(II) atom in an asymmetric fashion with one Cu‐N bond being much longer than the other, the Cu(II) atom is further coordinated by a pair of aqua ligands to form an elongated octahedral geometry. In the crystal of the complex, the mononuclear complex cations [Cu(AFO)2(H2O)2]2+, uncoordinated AFO molecules, lattice water molecules and perchlorate anions are assembled into 3‐D structure via hydrogen bonds and π‐π stacking interaction. 相似文献
14.
The title compound, C10H8N6O3, was synthesized by the reaction of 3‐(1H)‐1,2,4‐triazole hydrazine with 3‐nitrobenzaldehyde in ethanol. The single crystal structure has been determined by X‐ray analysis. The crystal belongs to monoclinic system, space group p21/c with cell constant, a = 8.0214(17) Å, b = 17.334(4) Å, c = 8.9070(18) Å, V= 1179.4(4) Å3. An intramolecular N—H...O and N—H…N hydrogen bond are observed between the ‐NH group with O atom of the carbonyl group and the ‐NH group with N atom. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
Ch. Y. Gao H. R. Xia J. Q. Xu Sh. Ch. Si H. J. Zhang J. Y. Wang 《Crystal Research and Technology》2008,43(4):443-446
The birefringence of (Ca0.28Ba0.72)0.75(Sr0.60Ba0.40)Nb2O6 crystal is measured basing on polarization‐ extinction method and conoscopic interference method. Experimental results show that the birefringence in this crystal is up to 10‐5, the natural birefringence in this crystal is (no ‐ne) = 5.89 x 10‐5 with the He‐Ne laser wavelength at 632.8nm and the birefringence grads with wavelength at 532nm is 5.68 x 10‐5, which indicate the good optical homogeneity of this crystal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
16.
A. A. Alybakov V. A. Gubanova G. S. Denisov N. Tojchiev 《Crystal Research and Technology》1977,12(11):1201-1204
The absorption spectrum of LiF—Fe3+ single crystals was investigated at liquid nitrogen temperature. Six new absorption bands, unobserved earlier in other works, were found, which were located at 11 200, 16 000, 22 700, 27300, 30 500, and 41 900 cm−1. The spectrum was interpreted in the cubic cristalline field approximation with Dq = 1397 cm−1, B = 657 cm−1, C = 3226 cm−1. Above mentioned bands were assigned to the transitions from a ground state 6A1g to the levels 4T1g(G), 4T2g(G), 4A1g(G) (4Eg), 4Eg(D), 2T1g(F), and 4T1g(F), respectively. 相似文献
17.
A. Nallini K. Saraboji M. N. Ponnuswamy S. B. Katti 《Crystal Research and Technology》2004,39(3):279-286
It is axiomatic that efficient crystal production reflects upon the quality of structure. An empirical relation for mass proportions of two solvents in crystallization of Z‐Tyr‐Gly‐OEt shows a linear relationship. The dipeptide crystallizes in orthorhombic space group P212121, with cell parameters a = 5.0680(1) Å, b = 13.8650(1) Å and c = 28.2630(1) Å, Z = 4, Dcalc= 1.339Mg/m3, μ=0.820mm‐1, F000=848, CuKα = 1.5418 Å. The structure was solved by direct methods and final R1 and wR2 are 0.444 and 0.1276, respectively. The structure analysis reveals the trans conformation of the peptide unit with ω = ‐178.2(5)°, implying only a slight deviation from planarity. The torsion angles at glycine [ϕ, ψ = ‐84.4(7)°, 179.9(5)°] are characteristic of left‐handed poly glycine II helices. A number of N‐H…O, O‐H…O and C‐H…O hydrogen bondings play a role in stabilizing the molecules within unit cell. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
Donggang Ran Hairui Xia Shangqian Sun Peng Zhao Fengqin Liu Zongcheng Ling Wenwei Ge Huaijin Zhang Jiyang Wang 《Crystal Research and Technology》2006,41(12):1189-1193
Barium tungstate (BaWO4) single crystal has been grown using Czochralski technique. It belongs to the scheelite structure, forming the space group I 41/a at room temperature and the primitive cell contains two molecular units. The polarized Raman spectra were recorded by a micro‐Raman spectrophotometer system in the backscattering geometry. All the observed Raman modes were assigned. The Raman mode at 924 cm–1, which belongs to the totally symmetrical Ag optical modes, has the strongest intensity and its linewidth is 4.6 cm–1. The infrared active lattice vibrations have been studied, eight optical modes were observed and assigned. The ultraviolet absorption edge is at 256 nm and the optical transparency range is up to 2500 nm at room temperature. The energy gap Eg of this crystal was obtained from the optical transmission spectra. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
Yan Wang Jianfu Li Chaoyang Tu Zhenyu You Zhaojie Zhu Baichang Wu 《Crystal Research and Technology》2007,42(11):1063-1067
This paper reports crystal growth and optical characteristics of dysprosium (Dy3+) and erbium (Er3+) doped mid‐infrared laser crystal ternary‐potassium‐lead‐chloride (KPb2Cl5). Two transparent crystals with good optical quality have been grown successfully by using the Bridgman technique,the largest crystal size reaches up to ∅︁10×60mm2. Measurements of X‐ray diffraction(XRD) and absorption spectra were carried out. Based on Judd‐Ofelt theory, the intensity parameters Ωt(t=2,4,6), the experimental and theoretical oscillator strengths have been obtained.The intensity parameters Ωt(t=2,4,6) of Er3+:KPb2Cl5 were calculated to be Ω2=5.10×10‐20 cm2, Ω4=1.25×10‐20 cm2, Ω6=0.83×10‐20 cm2, and the values for Dy3+:KPb2Cl5 were calculated to be Ω2=6.26×10‐20 cm2, Ω4=2.45×10‐20 cm2, Ω6=0.04×10‐20 cm2 respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
《Journal of chemical crystallography》1991,27(7):429-433
The [(L-aspartate)di(2-pyridyl)aminezinc(II)]hydrate doped with traces of copper was prepared. Electron paramagnetic resonance
spectra of the polycrystalline sample were recorded at room temperature by using the X-band of the EPR spectrometer. The observedg factors for the complex areg
‖=2.258 andg
⊥=2.066. TheA
‖ value is 165.10−4 cm−1. The crystal and molecular structure of the complex are also reported. The complex crystallizes in the monoclinic system;
space groupP21 witha=7.2053(11),b=10.447(2),c=10.812(2) Å, β=108.489(14)° andZ=2. The structure can be described in the crystal lattice as polymeric chains. 相似文献