Oxygen Stoichiometry and Superconductivity in Ho1Ba2Cu3O7−x

1987 ◽  
Vol 99 ◽  
Author(s):  
B. C. Sales ◽  
Y. C. Kim ◽  
J. R. Thompson ◽  
D. K. Christen ◽  
L. A. Boatner ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
High Resolution ◽  
Oxygen Vacancies ◽  
Oxygen Stoichiometry ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
General Shape ◽  
X Ray ◽  
Lattice Constants

ABSTRACTThe effects of varying oxygen content on the superconducting transition temperature Tc, resistivity, and crystal structure of HoBa2Cu3O7−x (0 < x < 1) have been investigated. The variation of Tc wltn 8 is very similar to that previously reported by several authors for YBa2Cu3O7−x [1,2]. In particular a plateau in the Tc vs x curve is observed for values of x between 0.3 and 0.4 witfi the value of Tc,(10 % onset measured magnetically) remaining relatively constant at about 55 K. The width of the superconducting transition, as measured both resistively and magnetically, is substantially narrower for x= 0.35 + 0.05 than for slightly larger or smaller values of x. High resolution powder x-ray diffraction analysis was used to measure the lattice constants of both the orthorhombic and tetragonal phases as x was varied. With increasing x the temperature coefficient of the resistivity changed from positive (metallic) for x ≤0.2 to negative (semiconducting) for x ≥, 0.3. Since the general shape of the Tc vs x curve was unaffected by the complete substitution of magnetic Ho for Y, these results suggest an ordering of the oxygen vacancies in the a-b plane and the existence of an ordered compound with a Tc of 55 K.

COMPOSITION DEPENDENCE OF SUPERCONDUCTIVITY AND CRYSTAL STRUCTURE IN La(Ba1−xCax)2Cu3O7−y SYSTEM

1989 ◽  
Vol 03 (04) ◽  
pp. 307-311 ◽  
Author(s):  
N. CAO ◽  
J.Q. ZHENG ◽  
X.Y. SHAO ◽  
X.S. CHEN ◽  
W.Y. GUAN
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Composition Dependence ◽  
Superconducting Transition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

The composition dependence of superconductivity and crystal structure in La ( Ba 1−x Ca x)2 Cu 3 O 7−y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till x=0.6, at which the zero resistance temperature of the sample is 81.5 K. In the meanwhile, the crystal structure of the sample changed from tetragonal (x=0) to orthorhombic structure (x=0.2, 0.4, 0.6). With further increase of Ca content, the superconductivity decrease for the sample of x=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2 K for the sample of x=1 without the ODP structure. A possible explanation of these experimental results is given.

Anionische Komplexe [Mo2(O2CPh)4X2]2⊖ mit X = N3, Cl, Br. Die Kristallstruktur von (PPh4)2[Mo2(O2CPh)4Cl2] · 2CH2Cl2 / Anionic Complexes [Mo2(O2C-Ph)4X2]2⊖ with X = N3, Cl, Br. The Crystal Structure of (PPh4)2[Mo2(O2C-Ph)4Cl2] · 2CH2Cl2

1985 ◽  
Vol 40 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Kay Jansen ◽  
Kurt Dehnicke ◽  
Dieter Fenske
Keyword(s):  
Crystal Structure ◽  
Ir Spectra ◽  
Diffraction Data ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Anionic Complexes

The syntheses and IR spectra of the complexes [Mo2(O2C-Ph)4X2]2⊖ with X = N3, CI, Br and the counter ion PPh4⊕ are reported. The azido and the bromo complexes are obtained from a solution of [Mo2(O2CPh)4] with PPh4N3 in pyridine or by reaction with PPh4Br in CH2Br2, respectively. When (PPh4)2[Mo2(O2CPh)4(N3)2] is dissolved in CH2Cl2, nitrogen is evolved and the complex with X = CI is obtained. The crystal structure of (PPh4)2[Mo2(O2CPh)4Cl2] · 2CH2Cl2 was determined from X-ray diffraction data (5676 observed independent reflexions, R = 0.042). It crystallizes in the monoclinic space group P21/n with four formula units per unit cell; the lattice constants are a = 1549, b = 1400, c = 1648 pm, β = 94.6°. The centrosymmetric [Mo2(O2CPh)4Cl2]2⊖ ion has a rather short Mo-Mo bond of 213 pm, whereas the MoCl bonds are very long (288 pm)

The crystal structure of visible light absorbing piezoelectric semiconductor SrNb2V2O11 revisited: high-resolution X-ray diffraction, vibrational spectroscopy and computational study

2019 ◽  
Vol 7 (18) ◽  
pp. 5497-5505
Author(s):  
Ievgen V. Odynets ◽  
Sergiy Khainakov ◽  
Santiago Garcia-Granda ◽  
Roman Gumeniuk ◽  
Matthias Zschornak ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Visible Light ◽  
Crystal Lattice ◽  
Vibrational Spectroscopy ◽  
Computational Study ◽  
X Ray Diffraction ◽  
Piezoelectric Semiconductor ◽  
X Ray

The crystal lattice of piezoelectric semiconductor Sr2Nb2V2O11 adopts Cc ordering due to Γ2− mode distortion.

scholarly journals Zur Darstellung und Kristallstruktur von β-NbO2 / Synthesis and Crystal Structure of β-NbO2

1982 ◽  
Vol 37 (11) ◽  
pp. 1361-1368 ◽  
Author(s):  
H.-J. Schweizer ◽  
Reginald Gruehn
Keyword(s):  
Crystal Structure ◽  
Long Range ◽  
Chemical Transport ◽  
Range Order ◽  
Long Range Order ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants

By using chemical transport reactions with various transporting agents (HgCl2, NbCl5, Nb3O7Cl) a slightly substoiehiometric NbO2-phase, β-NbO2, was obtained from samples with O/Nb ∼ 1.5 (source; T > 1373 K) and with deposition temperatures > 1273 K (sink). The rango of composition of β-NbO2 was found to exist from NbO1.990 to NbO1.998.The structure of the tetragonal, column-shaped black crystals was determined by X-ray diffraction. It crystallizes tetragonally in the space group I41 with lattice constants a = 9.693(3) Å, c = 5.985(1) Å and Z = 10 formula units.The crystal structure of β-NbO2 is shown to be a deformed rutile type. As in α-NbO2 the Nb-atoms are grouped in pairs. However, both oxides are different with respect to their long-range order.

Lattice parameters and optical absorption of CuIn1-xGaxSe2 thin films

1999 ◽  
Vol 77 (7) ◽  
pp. 515-520
Author(s):  
AAI Al-Bassam
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Thin Films ◽  
Grain Size ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Cubic Structure ◽  
Ga Content

Thin film polycrystalline solar cells based on CuIn1–xGaxSe2 have been fabricated and studied with x values from 0 to 1.0. The lattice parameters, grain size, and band gap were measured. Crystal structure and X-ray data of CuIn1–xGaxSe2 were determined using X-ray diffractometry. These materials had a cubic structure with x ≥ 0.5 and a tetragonal structure with x ≤ 0.5. The lattice constants vary linearly with composition. Grain size was measured using X-ray diffraction where the grain size increased linearly with Ga content. A grain size of 1.83-3.52 μm was observed with x ≤ 0.5, while it increased to 4.53 μm for x = 0.58.PACS No.: 70.73

Revisit of α-Chitin Crystal Structure Using High Resolution X-ray Diffraction Data

2009 ◽  
Vol 10 (5) ◽  
pp. 1100-1105 ◽  
Author(s):  
Pawel Sikorski ◽  
Ritsuko Hori ◽  
Masahisa Wada
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray

Structure of fluorite-like compound based on Nd5Mo3O16with lead partly substituting for neodymium

2015 ◽  
Vol 71 (2) ◽  
pp. 186-193 ◽  
Author(s):  
Alexander M. Antipin ◽  
Natalia I. Sorokina ◽  
Olga A. Alekseeva ◽  
Alexandra N. Kuskova ◽  
Elena P. Kharitonova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Single Crystal ◽  
Experimental Verification ◽  
X Ray Diffraction ◽  
Transmission Microscopy ◽  
X Ray ◽  
Oxygen Ion ◽  
First Time ◽  
Edx Microanalysis

A single crystal of Nd5Mo3O16with lead partly substituting for neodymium, which has a fluorite-like structure, was studied by precision X-ray diffraction, high-resolution transmission microscopy and EDX microanalysis. The crystal structure is determined in the space group Pn\bar 3n. It was found that the Pb atoms substitute in part for Nd atoms in the structure and are located in the vicinity of Nd2 positions. Partial substitutions of Mo cations for Nd positions and of Nd for Mo positions in crystals of theLn5Mo3O16oxide family are corroborated by X-ray diffraction for the first time. The first experimental verification of the location of an additional oxygen ion in the voids abutting MoO4tetrahedra was obtained.

Formamidinhim-Hexachloroferrat(III) Synthese und Kristallstruktur / Formamidinium-Hexachloroferrate(III) Synthesis and Crystal Structure

1985 ◽  
Vol 40 (3) ◽  
pp. 443-446 ◽  
Author(s):  
Udo Demant ◽  
Elke Conradi ◽  
Ulrich Müller ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
The Other ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Positional Disorder ◽  
Lattice Constants ◽  
Bond Lengths

[HC(NH2)2]3FeCl6 was obtained together with other products from the reaction of S4N4 with HCl in H2CCl2 in the presence of FeCl3. Its crystal structure was determined from X-ray diffraction data (473 independent observed reflexions, R = 0.047). Lattice constants: a = 961.6, c = 876.4 pm; tetragonal, space group P42/m, Z = 2. Of the two crystallographically independent formamidinium ions HC(NH2)2⊕, one exhibits positional disorder; the other one has C-N bond lengths of 128 pm. The FeCl63⊖ ions have symmetry C2h, but the deviation from Oh is small.

Cyclo-thiazenokomplexe von Vanadium(V) Die Kristallstruktur von (AsPh4)2[V(N3)3(N3S2)]2 · CH2Cl2 / Cyclo-thiazeno Complexes of Vanadium(V) The Crystal Structure of (AsPh4)2[V(N3)3(N3S2)]2 · CH2Cl2

1984 ◽  
Vol 39 (12) ◽  
pp. 1686-1695 ◽  
Author(s):  
Jürgen Hanich ◽  
Magda Krestel ◽  
Ulrich Müller ◽  
Kurt Dehnicke ◽  
Dieter Rehder
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Nmr Spectra ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Nmr Data ◽  
Donor Acceptor

An improved synthesis for [VCl2(N3S2)]∞, was found in the reaction of VOCl3 with (NSCl)3; when the reaction is performed in H2CCl2 and (NSCl)3 is used in excess, the thiazyl-solvate [VCl2(N3S2) · NSCl]2 is obtained. [VCl2(N3S2)] reacts with AsPh4Cl to form (AsPh4)2[VCl3(N 3S2)]2; this reacts with AgN3 in CH2Cl2 suspension to yield (AsPh4)2[V (N3)3(N3S2)]2 · CH2Cl2. The compounds were characterized by their IR and 51V NMR spectra. The latter are compared with new 51V NMR data for [VO2Cl2]⊖ and [VOCl4]⊖ ; a decrease of 51V shielding in the order [VO2Cl2]⊖ > [VOCl4]⊖ > [VX3(N3S2)]22⊖ (X - N3 > Cl) is found, which is interpreted in terms of increasing polarizability of the ligands and of ring contributions to the extreme deshielding observed with the thiazenovanadates.The crystal structure of (AsPh4)2[V(N3)3(N3S2)]2 · CH2Cl2 was determined from X-ray diffraction data (1496 observed reflexions, R = 0.058). It crystallizes in the triclinic space group P 1̄ with one formula unit per unit cell and with the lattice constants a - 1087, b = 1317, c = 1350 pm, α = 58.8, β = 85.9, γ = 68.0°. The structure consists of AsPh4⊕ ions, CH2Cl2 molecules and centrosymmetric [V(N3)3(N3S2)]22⊖ anions. In the latter. N3S2 ligands are bonded to the V atoms in a chelate manner with short V = N bonds (189 and 172 pm) forming planar VN3S2 rings. The dimerization is accomplished by V -N donor-acceptor interactions (224 pm) involving one N atom of each VN3S2 ring. The vanadium coordination number of 6 is com pleted by three azido groups with V -N bond distances of 200 to 204 pm.

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