The Quasi-Binary System CeCoC2-CeNiC2: Crystal Structure and Physical Properties

2019 ◽  
Vol 289 ◽  
pp. 114-119
Author(s):  
Herwig Michor ◽  
Alexander Schumer ◽  
Mykola Hembara ◽  
Bogdan Kotur ◽  
Volodymyr Levytskyy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Binary System ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Ground State ◽  
Kondo Lattice ◽  
Type Structure ◽  
Intermediate Region ◽  
X Ray ◽  
Quasi Binary System

The crystal structure of phases in the pseudo-binary system CeCo1–хNiхC2 (x = 0, 0.33, 0.5, 0.67, 0.79, 0.80, 0.83, 1) was investigated by means of X-ray powder diffraction. Co richer solid solutions CeCo1–хNiхC2 (0≤ x ≤0.5) crystallize in the monoclinic CeCoC2-type structure; a = 5.3968(2) Å, b = 5.4013(3) Å, c = 7.4762(3) Å, β = 102.136(3)°, V = 213.06(3) Å3 for x = 0.5. Ni-rich CeNi1–yCoyC2 (0≤ y ≤0.2) are isotypic with the orthorhombic CeNiC2-type structure, a = 3.8486(2) Å, b = 4.5479(2) Å, c = 6.1531(3) Å, V = 107.70(1) Å3 for y = 0.2. In the intermediate region (0.5< x <0.79) both phases, CeCo0.21Ni0.79C2 and CeCo0.5Ni0.5C2, coexist. The non-isoelectronic substitution of Ni by Co in solid solutions CeNi1–yCoyC2 causes a continuous reduction of the Néel temperature and finally, for CeCoC2, results in a paramagnetic Kondo-lattice ground state.

High-temperature X-ray powder diffraction study of the tetragonal-cubic phase transition in nanocrystalline, compositionally homogeneous ZrO2–CeO2 solid solutions

2008 ◽  
Vol 23 (S1) ◽  
pp. S70-S74 ◽  
Author(s):  
L. M. Acuña ◽  
R. O. Fuentes ◽  
D. G. Lamas ◽  
I. O. Fábregas ◽  
N. E. Walsöe de Reca ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray ◽  
First Order

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

The lattice parameters and interplanar spacings of some artificially prepared melilites

1948 ◽  
Vol 28 (202) ◽  
pp. 374-379 ◽  
Author(s):  
K. W. Andrews
Keyword(s):  
Crystal Structure ◽  
Blast Furnace ◽  
Binary System ◽  
Laboratory Investigation ◽  
Solid Solutions ◽  
Lattice Parameters ◽  
Refractive Indices ◽  
X Ray ◽  
Tetragonal Lattice ◽  
Intermediate Series

A laboratory investigation in connexion with some blast-furnace slags, led to the preparation of the five synthetic melilites for which X-ray data are provided. The five compounds represent gehlenite, åkermanite and three members of the intermediate series of solid solutions, corresponding to 25, 50, and 75 % of åkermanite.The binary system gehlenite–åkermanite was studied by Ferguson and Buddington, who established relationships between refractive indices, density, and composition and determined solidus and liquidus curves. The crystal structure of the melilite group of compounds was investigated by Warren, who showed that the structure was based on a tetragonal lattice.

Phase diagram of the Nd2Fe14B–Sm2Fe14B pseudo-binary system

2016 ◽  
Vol 49 (1) ◽  
pp. 64-68 ◽  
Author(s):  
Ch. F. Xu ◽  
K. H. Chen ◽  
Z. F. Gu ◽  
L. Y. Cheng ◽  
D. D. Ma ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Diagram ◽  
Binary System ◽  
Solid Solutions ◽  
Structure Parameters ◽  
Rietveld Refinements ◽  
X Ray ◽  
Full Profile ◽  
Cell Volumes ◽  
Scanning Electron

The phase relations in the (1−x)Nd2Fe14B–xSm2Fe14B system over the whole concentration range have been studied by means of X-ray powder diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Crystal structure parameters for all studied compositions of (Nd1−xSmx)2Fe14B have been determined by full-profile Rietveld refinements. These results revealed that all intermediate alloys of (Nd1−xSmx)2Fe14B are similar to the end member of the investigated system, Nd2Fe14B, with a tetragonal structure (space groupP42/mnm). The formation of continuous solid solutions has been found in this system. The normalized lattice parameters and unit-cell volumes of (Nd1−xSmx)2Fe14B solid solutions decrease linearly with increasing Sm content. The DTA measurements show that the melting temperature of (Nd1−xSmx)2Fe14B increases linearly with increasing Sm content and no metastable phases were detected. Based on the DTA data and XRD results, a tentative phase diagram for the pseudo-binary system Nd2Fe14B–Sm2Fe14B has been constructed.

scholarly journals Crystal structure of mechanochemically synthesized Ag2CdSnS4

2020 ◽  
Vol 75 (4) ◽  
pp. 393-402 ◽  
Author(s):  
Eva M. Heppke ◽  
Stefan Berendts ◽  
Martin Lerch
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Powder Diffraction ◽  
Mechanochemical Synthesis ◽  
Type Structure ◽  
Structural Investigations ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Acta Crystallogr

AbstractAg2CdSnS4 was synthesized by a two step mechanochemical synthesis route. From a detailed analysis of the observed reflections in the X-ray powder diffraction pattern, the crystal structure proposed in the literature (space group Cmc21 [E. Parthé, K. Yvon, R. H. Deitch, Acta Crystallogr.1969, B25, 1164–1174; O. V. Parasyuk, I. D. Olekseyuk, L. V. Piskach, S. V. Volkov, V. I. Pekhnyo, J. Alloys Compd.2005, 399, 173–177]) is questionable. Our structural investigations presented in this contribution point to the fact that Ag2CdSnS4 crystallizes in the monoclinic wurtzkesterite-type structure (space group Pn). At around T = 200°C, a phase transition to the orthorhombic wurtzstannite-type structure (space group Pmn21) is observed.

Synthesis and crystal structure of the pyrovanadate Na2ZnV2O7

2005 ◽  
Vol 20 (3) ◽  
pp. 189-192 ◽  
Author(s):  
Alexander P. Tyutyunnik ◽  
Vladimir G. Zubkov ◽  
Ludmila L. Surat ◽  
Boris V. Slobodin ◽  
Gunnar Svensson
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Neutron Powder Diffraction ◽  
Type Structure ◽  
Powder Diffraction Data ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Neutron Powder Diffraction Data ◽  
Tetragonal Unit Cell

The compound Na2ZnV2O7 with an åkermanite-type structure has been synthesized. It has a tetragonal unit cell, a=8.2711(4), c=5.1132(2) Å, and crystallizes with P-421m symmetry, Z=2. Its crystal structure has been refined from a combination of X-ray and neutron powder diffraction data. The structure contains layers of corner-sharing VO4 and ZnO4 tetrahedra, the former in pairs forming pyrovanadate V2O7 units. The sodium atoms are positioned between the layers, with a distorted antiprismatic coordination of oxygen atoms.

scholarly journals Crystal structure of pimecrolimus Form B, C43H68ClNO11

2021 ◽  
Vol 36 (1) ◽  
pp. 35-42
Author(s):  
Shivang Bhaskar ◽  
Joseph T. Golab ◽  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Density Functional ◽  
Van Der Waals Interactions ◽  
Powder Diffraction File ◽  
X Ray ◽  
Weak Intermolecular Interactions ◽  
Significant Difference ◽  
Atomic Coordinates ◽  
Solid State Conformation

The crystal structure of pimecrolimus Form B has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Pimecrolimus crystallizes in the space group P21 (#4) with a = 15.28864(7), b = 13.31111(4), c = 10.95529(5) Å, β = 96.1542(3)°, V = 2216.649(9) Å3, and Z = 2. Although there are an intramolecular six-ring hydrogen bond and some larger chain and ring patterns, the crystal structure is dominated by van der Waals interactions. There is a significant difference between the conformation of the Rietveld-refined and the DFT-optimized structures in one portion of the macrocyclic ring. Although weak, intermolecular interactions are apparently important in determining the solid-state conformation. The powder pattern is included in the Powder Diffraction File™ (PDF®) as entry 00-066-1619. This study provides the atomic coordinates to be added to the PDF entry.

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