On Some Ternary Phases in the Systems Nb-Zn-Al and Ta-Zn-Al

1982 ◽  
Vol 37 (10) ◽  
pp. 1225-1229 ◽  
Author(s):  
A. Drašner ◽  
Ž. Blažina
Keyword(s):  
Valence Electron ◽  
Ternary Phase ◽  
Single Phase ◽  
Phase Region ◽  
Valence Electron Concentration ◽  
Unit Cell Parameters ◽  
Laves Phases ◽  
X Ray ◽  
Cell Parameters ◽  
The Stability

Abstract In the systems NbZn2-xALx and TaZn2-xAlx a great number of samples was prepared and investigated by means of X-ray powder diffraction. In both systems at the equiatomic composition two new ternary phases were found. Their crystal structures were determined and found to belong to the Friauf-Laves type (MgZn2 prototype, S. G. P 63/mmc). The unit cell parameters of NbZnAl are a = 506.4 ± 0.2 pm, c = 829.9 ± 0.8 pm, c/a = 1.639, and for TaZnAl a = 503.8 ± 0.2 pm, c = 827.9 ± 0.3 pm, c/a= 1.643. In the system NbZn2-x-Alx, at the composition NbZn1.25Al0.75, a ternary phase of the AuCu3 structure (a= 394.4 i 0.3 pm, S. G. Pm3m) was also observed, while in the system NbZn3-xAlx a single phase region, having the AuCu3 structure, was found to exist up to the composition NbZ2Al. The stability of these Friauf-Laves phases and those found previously in the systems ZrZn2-xAlx and HfZn2-xAlx is discussed in terms of atomic sizes and valence electron concentration.

Anomalous phase composition in the two-phase region of DyFe3−xAlx (x≤1.0)

2010 ◽  
Vol 25 (4) ◽  
pp. 349-354 ◽  
Author(s):  
Y. Q. Chen ◽  
J. K. Liang ◽  
J. Luo ◽  
J. B. Li ◽  
G. H. Rao
Keyword(s):  
Phase Region ◽  
Hexagonal Structure ◽  
Unit Cell Parameters ◽  
Two Phase ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Two Phases ◽  
Xrd Patterns ◽  
Phase Relationships

The structure transitions and phase relationships of DyFe3−xAlx compounds have been investigated by X-ray powder diffraction. Our XRD results show that each of the compounds with x≤0.45 crystallizes in the rhombohedral PuNi3-type structure with space group R3¯m and Z=9; for the 0.8≤x<1.0 compounds, each has a hexagonal structure of the CeNi3 type with space group P63/mmc and Z=6; and each of the samples with 0.45<x<0.8 is a two-phase mixture of the PuNi3- and CeNi3-type structures. The calculated XRD intensities of the DyFe3−xAlx compounds with x=0.2, 0.33, 0.4, and 0.45 indicate that Dy occupies the 3a and 6c sites, Fe and Al distribute randomly on the 18h site, and the 3b and 6c sites are exclusively occupied by Fe, which agrees well with those of our experimental XRD patterns. The XRD intensities of the DyFe3−xAlx compounds with x=0.8 and 1.0 have also been calculated and found to agree with the experimental results with Dy on the 2c and 4f sites, Fe and Al at the 12k site, and Fe at the 2a, 2b, and 2d sites. In the two-phase region with x=0.45–0.8, the values of unit-cell parameters and phase compositions are linearly dependent on the value of x, indicating that the two phases are constituted by the same composition x with different stacking arrangements. This abnormal two-phase equilibrium is further confirmed by the structural analysis of the DyFe2.33Al0.67 (or x=0.67) sample. The samples with x=1.1 and 1.2 were also analyzed, and each found to be a mixture of more than two phases.

The f.c.c.+tetragonal two-phase region of the Cu–Ni–Zn system

1983 ◽  
Vol 16 (1) ◽  
pp. 99-102 ◽  
Author(s):  
O. S. Mayall
Keyword(s):  
Tetragonal Phase ◽  
Lattice Spacing ◽  
Single Phase ◽  
Phase Region ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Two Phase ◽  
Cell Parameters ◽  
Tie Lines

The f.c.c. + tetragonal two-phase region of the Cu–Ni–Zn system has been delineated, and unit-cell parameters along the boundaries determined. Apparently anomalous parameter measurements prevented the determination of the tie lines. A pattern of diffraction broadening from the tetragonal phase common to both the two-phase and single-phase regions was related to the variation in lattice spacing of the tetragonal phase along the boundary. Reasons for this broadening are discussed.

THE SUPERCONDUCTING STUDY OF TlBaCaCu2Oy

1988 ◽  
Vol 02 (09) ◽  
pp. 1095-1101
Author(s):  
JIE YAN ◽  
XIAOMING YANG ◽  
GUANGWEN PEI ◽  
ZHENYU MEN ◽  
DEYING SONG
Keyword(s):  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Sintering Atmosphere ◽  
X Ray ◽  
Cell Parameters ◽  
Sintering Time ◽  
Zero Resistance ◽  
Annealing Rate ◽  
The Stability

The relation of the superconductivity of TlBaCaCu 2 O y to the sintering temperature, sintering time, annealing rate and sintering atmosphere was studied. It was shown that the zero-resistance temperature of the superconductors of the type was up to 118K and the stability was to some extent quite good. Through X-ray diffraction analysis, the TlBaCaCu 2 O y was found to possess two kinds of tetragonal structures. The T co =118 K sample has the unit cell parameters of a=5.446(2)Å, c=35.698(2)Å; while for T co =93.5 K , one has the parameters of a=5.469(2)Å, c=30.051(2)Å, the substitution of Tl, Ba, Ca , by many other elements show that only TlBaMgCu 2 O y and TlMg 2 Cu 2 O y are superconductors and others are insulators.

Rb4Au7Sn2, eine intermetallische Phase mit siebenatomigen Goldclustern/ Rb4Au7Sn2, an Intermetallic Phase with Sevenatomic Gold-Clusters

1981 ◽  
Vol 36 (7) ◽  
pp. 833-836 ◽  
Author(s):  
Heinz-Dieter Sinnen ◽  
Hans-Uwe Schuster
Keyword(s):  
Crystal Structure ◽  
Ternary System ◽  
Diffraction Data ◽  
Intermetallic Phase ◽  
Gold Clusters ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Laves Phases ◽  
X Ray ◽  
Cell Parameters

AbstractIn the course of our investigations of the ternary system Rb-Au-Sn we obtained the new compound Rb4Au7Sn2. Its crystal structure has been determined by single crystal X-ray diffraction data. It crystallizes in the hexagonal (rhombohedral) space group R3̄m with unit-cell parameters a = 680.1(3) pm and c = 2909.0(7) pm, and Z = 3. The structure is similar to that of Laves-Phases of the MgCu2-type.

Rietveld refinement of X-ray powder diffraction data of Ca0.925Ce0.075Mn0.9Fe0.1O3 polycrystalline material

2018 ◽  
Vol 33 (4) ◽  
pp. 303-305
Author(s):  
G. Murugesan ◽  
K. R. Nandan ◽  
S. Kalainathan
Keyword(s):  
Single Phase ◽  
Polycrystalline Material ◽  
General Structure ◽  
Sol Gel ◽  
Powder Diffraction Data ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

Polycrystalline Ca0.925Ce0.075Mn0.9Fe0.1O3 were prepared by sol-gel reaction at 1073 K. The compound was analyzed by a powder X-ray diffraction technique and found to be in single phase. The unit-cell parameters and atomic positions were refined using General Structure Analysis to an orthorhombic structure with space group Pnma (#62) a = 5.281 90 (33) Å, b = 7.4968 (45) Å, and c = 5.302 90 (32) Å.

scholarly journals X-ray structure of Arthrobacter globiformis M30 ketose 3-epimerase for the production of D-allulose from D-fructose

2018 ◽  
Vol 74 (10) ◽  
pp. 669-676 ◽  
Author(s):  
Hiromi Yoshida ◽  
Akihide Yoshihara ◽  
Pushpa Kiran Gullapalli ◽  
Kouhei Ohtani ◽  
Kazuya Akimitsu ◽  
...  
Keyword(s):  
Search Model ◽  
Molecular Replacement ◽  
Arthrobacter Globiformis ◽  
Hexagonal Crystal ◽  
Unit Cell Parameters ◽  
Mesorhizobium Loti ◽  
X Ray ◽  
Cell Parameters ◽  
Sequence Identity ◽  
The Stability

The X-ray structure of ketose 3-epimerase from Arthrobacter globiformis M30, which was previously reported to be a D-allulose 3-epimerase (AgD-AE), was determined at 1.96 Å resolution. The crystal belonged to the hexagonal space group P6522, with unit-cell parameters a = b = 103.98, c = 256.53 Å. The structure was solved by molecular replacement using the structure of Mesorhizobium loti L-ribulose 3-epimerase (MlL-RE), which has 41% sequence identity, as a search model. A hexagonal crystal contained two molecules in the asymmetric unit, and AgD-AE formed a homotetramer with twofold symmetry. The overall structure of AgD-AE was more similar to that of MlL-RE than to the known structures of D-psicose (alternative name D-allulose) 3-epimerases (D-PEs or D-AEs), although AgD-AE and MlL-RE have different substrate specificities. Both AgD-AE and MlL-RE have long helices in the C-terminal region that would contribute to the stability of the homotetramer. AgD-AE showed higher enzymatic activity for L-ribulose than D-allulose; however, AgD-AE is stable and is a unique useful enzyme for the production of D-allulose from D-fructose.

Electrical and dielectric behavior of Pb(Mg1/4Ni1/4W1/2)O3 ceramics

2004 ◽  
Vol 829 ◽  
Author(s):  
Adolfo Franco Júnior
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dielectric Constant ◽  
Single Phase ◽  
Dielectric Behavior ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Dielectric Constant And Loss ◽  
Scanning Electron

ABSTRACTIn this study full dense polycrystalline samples of Pb(Mg1/4Ni1/4W1/2)O3 have been sintered by solid-state reaction. X-ray data showed the formation of a single-phase new compound with unit cell parameters a = 9.8045 (25) Å, b = 13.1280(25) Å and c = 14.4207 (25) Å. Scanning electron microscopy (SEM) was used to evaluate the microstructures of sintered specimens. Dielectric constant and loss as function of frequency were investigated.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

scholarly journals Crystallization and preliminary X-ray diffraction analysis of the Csu pili CsuC–CsuA/B chaperone–major subunit pre-assembly complex fromAcinetobacter baumannii

2015 ◽  
Vol 71 (6) ◽  
pp. 770-774 ◽  
Author(s):  
Natalia Pakharukova ◽  
Minna Tuittila ◽  
Sari Paavilainen ◽  
Anton Zavialov
Keyword(s):  
Diffusion Method ◽  
X Ray Diffraction ◽  
Hanging Drop ◽  
Unit Cell Parameters ◽  
Gram Negative ◽  
X Ray ◽  
Cell Parameters ◽  
Abiotic Surfaces ◽  
Vapour Diffusion ◽  
Fimbrial Adhesins

The attachment of many Gram-negative pathogens to biotic and abiotic surfaces is mediated by fimbrial adhesins, which are assembledviathe classical, alternative and archaic chaperone–usher (CU) pathways. The archaic CU fimbrial adhesins have the widest phylogenetic distribution, yet very little is known about their structure and mechanism of assembly. To elucidate the biogenesis of archaic CU systems, structural analysis of the Csu fimbriae, which are used byAcinetobacter baumanniito form stable biofilms and cause nosocomial infection, was focused on. The major fimbriae subunit CsuA/B complexed with the CsuC chaperone was purified from the periplasm ofEscherichia colicells co-expressing CsuA/B and CsuC, and the complex was crystallized in PEG 3350 solution using the hanging-drop vapour-diffusion method. Selenomethionine-labelled CsuC–CsuA/B complex was purified and crystallized under the same conditions. The crystals diffracted to 2.40 Å resolution and belonged to the hexagonal space groupP6422, with unit-cell parametersa=b= 94.71,c = 187.05 Å, α = β = 90, γ = 120°. Initial phases were derived from a single anomalous diffraction (SAD) experiment using the selenomethionine derivative.

Silicate-germanate K2Y[(Si3Ge)O10(OH)] with unusual complex corrugated layer and its correlation to ring silicate gerenite and chain silicate chkalovite

2020 ◽  
Vol 235 (4-5) ◽  
pp. 167-172
Author(s):  
Anastasiia P. Topnikova ◽  
Elena L. Belokoneva ◽  
Olga V. Dimitrova ◽  
Anatoly S. Volkov ◽  
Leokadiya V. Zorina
Keyword(s):  
Low Temperature ◽  
Cross Section ◽  
Complex Anion ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Chain Silicate ◽  
Novel Complex

AbstractA new silicate-germanate K2Y[(Si3Ge)O10(OH)] was synthesized hydrothermally in a system Y2O3:GeO2:SiO2 = 1:1:2 (T = 280 °C; P = 90–100 atm.); K2CO3 was added to the solution as a mineralizer. Single-crystal X-ray diffraction experiment was carried out at low temperature (150 K). The unit cell parameters are a = 10.4975(4), b = 6.9567(2), c = 15.4001(6) Å, β = 104.894(4)°; V = 1086.86(7) Å3; space group is P 21/c. A novel complex anion is presented by corrugated (Si,Ge) tetrahedral layers connected by couples of YO6 octahedra into the mixed microporous framework with the channels along b and a axes, the maximal size of cross-section is ~5.6 Å. This structure has similarity with the two minerals: ring silicate gerenite (Ca,Na)2(Y,REE)3Si6O18 · 2H2O and chain silicate chkalovite Na2BeSi2O6. Six-member rings with 1̅ symmetry as in gerenite are distinguished in the new layer. They are mutually perpendicular to each other and connected by additional tetrahedra. Straight crossing chains in chkalovite change to zigzag four-link chains in the new silicate-germanate layer.

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