Crystal structure of adamite at high temperature

2016 ◽  
Vol 80 (5) ◽  
pp. 901-914 ◽  
Author(s):  
M. Zema ◽  
S. C. Tarantino ◽  
M. Boiocchi ◽  
A. M. Callegari
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Expansion ◽  
Cell Parameters ◽  
Temperature Range ◽  
Linear Evolution ◽  
Thermal Expansion Coefficients ◽  
Different Temperatures ◽  
Increasing Temperature

AbstractStructural modifications with temperature of adamite, Zn2(AsO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and collapse of the crystal structure. In the temperature range 25–400°C, adamite shows positive and linear expansion. Axial thermal expansion coefficients, determined over this temperature range, are αa = 1.06(2) × 10–5 K–1, αb = 1.99(2) × 10–5 K–1, αc = 3.7(1) × 10–6 K–1 and αV = 3.43(3) × 10–5 K–1. Axial expansion is then strongly anisotropic with αa:αb:αc = 2.86: 5.38 : 1. Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the adamite structure accommodates variations in temperature. Expansion is limited mainly by edge sharing Zn(2) dimers along a and by edge sharing Zn(1) octahedra chains along c; on the other hand, connections of polyhedra along b, the direction of maximum expansion, is governed by corner sharing. Increasing temperature induces mainly an axial expansion of Zn(1) octahedron, which becomes more elongated, and no significant variations of the Zn(2) trigonal bipyramids and As tetrahedra. Starting from 400°C, deviation from a linear evolution of unit-cell parameters is observed, associated with some deterioration of the crystal, a sign of incipient dehydration. The process leads to the formation of Zn4(AsO4)2O.

Thermal behaviour of libethenite from room temperature up to dehydration

2010 ◽  
Vol 74 (3) ◽  
pp. 553-565 ◽  
Author(s):  
M. Zema ◽  
S. C. Tarantino ◽  
A. M. Callegari
Keyword(s):  
X Ray Diffraction ◽  
Oh Groups ◽  
X Ray ◽  
Structural Modifications ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Different Temperatures ◽  
Expansion Coefficients ◽  
Increasing Temperature ◽  
Diffraction Effects

AbstractThe structural modifications with temperature of libethenite, Cu2(PO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and consequent decomposition of the crystal under investigation. In the temperature range 25–475°C, libethenite shows positive and linear expansion. The axial thermal expansion coefficients, determined over this temperature range, are: αa = 6.6(1)·10–6 K–1, αb = 1.21(2)·10–5 K–1, αc = 9.0(2)·10–6 K–1, αv = 2.78(3)·10–5 K–1. Axial expansion is then anisotropic with αa:αb:αc = 1:1.83:1.33.Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the libethenite structure accommodates variations in temperature. Increasing temperature induces expansion of both Cu polyhedra and no significant variation of the PO4 tetrahedron, which acts as a rigid unit. Cu(1) octahedra expand mostly as a consequence of the increase of the axial bonds, and become more distorted. Starting from T = 500°C, precursor signs of incoming dehydration are visible: two adjacent OH groups approach each other and cause dramatic changes in the whole structure. Concomitantly, the libethenite crystal begins to deteriorate and, at T = 600°C, broad and weak diffraction effects of polycrystalline material are observed.

Crystal structure and thermal expansion of hexakis(phenylthio)benzene and its CBr4 clathrate

1995 ◽  
Vol 73 (4) ◽  
pp. 513-521 ◽  
Author(s):  
Darek Michalski ◽  
Mary Anne White ◽  
Pradip K. Bakshi ◽  
T. Stanley Cameron ◽  
Ian Swainson
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Neutron Powder Diffraction ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

The crystal structures of hexakis(phenylthio)benzene (HPTB) and its CBr4 clathrate have been determined by single crystal X-ray diffraction data collected at T = 18 °C and refined to final Rw of 0.036 and 0.047, respectively. Pure HPTB is triclinic, space group [Formula: see text] (No. 2), with a = 9.589(2) Å, b = 10.256(1) Å, c = 10.645(2) Å, α = 68.42(1)°, β = 76.92(2)°, γ = 65.52(1)°, and Z = 1. The CBr4 clathrate of HPTB is rhombohedral, space group [Formula: see text] (No. 148), with a = 14.327(4) Å, b = 20.666(8) Å, and Z = 3. The host–guest mole ratio of HPTB–CBr4 is 1:2. Neutron powder diffraction was carried out on powders of both compounds in the temperature range 25 K < T < 295 K. Thermal expansion coefficients were determined for HPTB and HPTB–CBr4 over this temperature range. Keywords: thermal expansion, crystal structure, clathrate.

Crystal Structure and Thermal Expansion of Ge-Doped Mn3CuN

2011 ◽  
Vol 412 ◽  
pp. 422-426
Author(s):  
Xue Yan ◽  
Z. Hua ◽  
J. Liu ◽  
Bin Li ◽  
X. Cheng
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Refinement Method ◽  
Different Temperatures ◽  
N Powder

The Ge doped Mn3CuN powder was synthesized using gas-solid reaction method with manganese, copper, germanium powders and N2 gas as raw material. The phase constitute of the as-prepared powder was characterized using X-ray diffraction (XRD). The intrinsic and macro thermal expansion coefficients of the powder were measured by in-situ X-ray diffraction at different temperatures and TMA, respectively. The crystal structure of the powders was analyzed using Rietveld refinement method. The results show that the pure Mn3(Cu0.5Ge0.5)N powder can be prepared via the gas-solid method at 850 °C. The crystal structures of Mn3(Cu0.5Ge0.5)N and Mn3CuN both have the antiperovskite structures. The intrinsic and macro thermal expansion coefficient of Mn3(Cu0.5Ge0.5)N powder is-16.8×10-6K-1 and-17×10-6K-1, respectively. The temperature range with negative thermal expansion is from-80 °C to 50 °C.

X-ray powder diffraction data of LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites

2021 ◽  
pp. 1-6
Author(s):  
Mariana M. V. M. Souza ◽  
Alex Maza ◽  
Pablo V. Tuza
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Pechini Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Modified Pechini Method ◽  
Scanning Electron

In the present work, LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites were synthesized by the modified Pechini method. These materials were characterized using X-ray fluorescence, scanning electron microscopy, and powder X-ray diffraction coupled to the Rietveld method. The crystal structure of these materials is orthorhombic, with space group Pbnm (No 62). The unit-cell parameters are a = 5.535(5) Å, b = 5.527(3) Å, c = 7.819(7) Å, V = 239.2(3) Å3, for the LaNi0.5Ti0.45Co0.05O3, a = 5.538(6) Å, b = 5.528(4) Å, c = 7.825(10) Å, V = 239.5(4) Å3, for the LaNi0.45Co0.05Ti0.5O3, and a = 5.540(2) Å, b = 5.5334(15) Å, c = 7.834(3) Å, V = 240.2(1) Å3, for the LaNi0.5Ti0.5O3.

scholarly journals Crystal Structure Refinements of Four Monazite Samples from Different Localities

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1028 ◽  
Author(s):  
M. Mashrur Zaman ◽  
Sytle M. Antao
Keyword(s):  
Crystal Structure ◽  
Electron Probe ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Large Unit Cell ◽  
A Site

This study investigates the crystal chemistry of monazite (APO4, where A = Lanthanides = Ln, as well as Y, Th, U, Ca, and Pb) based on four samples from different localities using single-crystal X-ray diffraction and electron-probe microanalysis. The crystal structure of all four samples are well refined, as indicated by their refinement statistics. Relatively large unit-cell parameters (a = 6.7640(5), b = 6.9850(4), c = 6.4500(3) Å, β = 103.584(2)°, and V = 296.22(3) Å3) are obtained for a detrital monazite-Ce from Cox’s Bazar, Bangladesh. Sm-rich monazite from Gunnison County, Colorado, USA, has smaller unit-cell parameters (a = 6.7010(4), b = 6.9080(4), c = 6.4300(4) Å, β = 103.817(3)°, and V = 289.04(3) Å3). The a, b, and c unit-cell parameters vary linearly with the unit-cell volume, V. The change in the a parameter is large (0.2 Å) and is related to the type of cations occupying the A site. The average <A-O> distances vary linearly with V, whereas the average <P-O> distances are nearly constant because the PO4 group is a rigid tetrahedron.

Refinement of the crystal structure of sieleckiite and revision of its symmetry

2017 ◽  
Vol 81 (4) ◽  
pp. 917-922
Author(s):  
Peter Elliott
Keyword(s):  
Crystal Structure ◽  
Synchrotron Radiation ◽  
Single Crystal ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Aluminium Phosphate ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Phosphate Mineral

AbstractThe crystal structure of the copper aluminium phosphate mineral sieleckiite, Cu3Al4(PO4)2 (OH)12·2H2O, from the Mt Oxide copper mine, Queensland, Australia was solved from single-crystal X-ray diffraction data utilizing synchrotron radiation. Sieleckiite has monoclinic rather than triclinic symmetry as previously reported and is space group C2/m with unit-cell parameters a = 11.711(2), b = 6.9233(14), c = 9.828(2) Å, β = 92.88(3)°, V = 795.8(3) Å3and Z = 2. The crystal structure, which has been refined to R1 = 0.0456 on the basis of 1186 unique reflections with Fo > 4σF, is a framework of corner-, edge- and face- sharing Cu and Al octahedra and PO4 tetrahedra.

Synthesis and crystal structure of (Ag,Pd)22Se6

2013 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
D.A. Chareev ◽  
A.V. Kristavchuk ◽  
J. Drahokoupil ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Glass Tube ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters ◽  
Silica Glass Tube

The (Ag,Pd)22Se6 phase was synthesized from individual elements by silica glass tube technique and structurally characterized from powder X-ray diffraction data. The (Ag,Pd)22Se6 phase crystallizes in Fm$\overline3$m symmetry, unit-cell parameters: a = 12.3169(2) Å, V = 1862.55(5) Å3, Z = 4, and Dc = 10.01 g/cm3. The crystal structure of the (Ag,Pd)22Se6 phase represents a stuffed 3a.3a.3a superstructure of the Pd structure (fcc), where only 4 from 108 available octahedral holes are occupied. Its crystal structure is related to the Cr23C6 structure type.

scholarly journals Expression, purification, crystallization and X-ray diffraction studies of the molecular chaperone prefoldin fromHomo sapiens

2015 ◽  
Vol 71 (9) ◽  
pp. 1189-1193 ◽  
Author(s):  
Yoshiki Aikawa ◽  
Hiroshi Kida ◽  
Yuichi Nishitani ◽  
Kunio Miki
Keyword(s):  
Crystal Structure ◽  
Protein Folding ◽  
Diffraction Data ◽  
Molecular Chaperone ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Native Proteins ◽  
Group Ii Chaperonin

Proper protein folding is an essential process for all organisms. Prefoldin (PFD) is a molecular chaperone that assists protein folding by delivering non-native proteins to group II chaperonin. A heterohexamer of eukaryotic PFD has been shown to specifically recognize and deliver non-native actin and tubulin to chaperonin-containing TCP-1 (CCT), but the mechanism of specific recognition is still unclear. To determine its crystal structure, recombinant human PFD was reconstituted, purified and crystallized. X-ray diffraction data were collected to 4.7 Å resolution. The crystals belonged to space groupP21212, with unit-cell parametersa= 123.2,b= 152.4,c= 105.9 Å.

scholarly journals Redetermination of Sr2PdO3 from single-crystal X-ray data

2019 ◽  
Vol 75 (1) ◽  
pp. 30-32
Author(s):  
Gohil S. Thakur ◽  
Hans Reuter ◽  
Claudia Felser ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Structure Type ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cell Parameters ◽  
Anisotropic Displacement Parameters

The crystal structure redetermination of Sr2PdO3 (distrontium palladium trioxide) was carried out using high-quality single-crystal X-ray data. The Sr2PdO3 structure has been described previously in at least three reports [Wasel-Nielen & Hoppe (1970). Z. Anorg. Allg. Chem. 375, 209–213; Muller & Roy (1971). Adv. Chem. Ser. 98, 28–38; Nagata et al. (2002). J. Alloys Compd. 346, 50–56], all based on powder X-ray diffraction data. The current structure refinement of Sr2PdO3, as compared to previous powder data refinements, leads to more precise cell parameters and fractional coordinates, together with anisotropic displacement parameters for all sites. The compound is confirmed to have the orthorhombic Sr2CuO3 structure type (space group Immm) as reported previously. The structure consists of infinite chains of corner-sharing PdO4 plaquettes interspersed by SrII atoms. A brief comparison of Sr2PdO3 with the related K2NiF4 structure type is given.

scholarly journals Redetermination of the crystal structure of RhPb2 from single-crystal X-ray diffraction data, revealing a rhodium deficiency

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Takashi Mochiku ◽  
Yoshitaka Matsushita ◽  
Nikola Subotić ◽  
Takanari Kashiwagi ◽  
Kazuo Kadowaki
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Type ◽  
Site Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Anisotropic Displacement Parameters ◽  
Slight Deficiency

RhPb2 (rhodium dilead) is a superconductor crystallizing in the CuAl2 structure type (space group I4/mcm). The Rh and Pb atoms are located at the 4a (site symmetry 422) and 8h (m.2m) sites, respectively. The crystal structure is composed of [RhPb8] antiprisms, which share their square faces along the c axis and the edges in the direction perpendicular to the c axis. We have succeeded in growing single crystals of RhPb2 and have re-determined the crystal structure on basis of single-crystal X-ray diffraction data. In comparison with the previous structure studies using powder X-ray diffraction data [Wallbaum (1943). Z. Metallkd. 35, 218–221; Havinga et al. (1972). J. Less-Common Met. 27, 169–186], the current structure analysis of RhPb2 leads to more precise unit-cell parameters and fractional coordinates, together with anisotropic displacement parameters for the two atoms. In addition and likewise different from the previous studies, we have found a slight deficiency of Rh in RhPb2, leading to a refined formula of Rh0.950 (9)Pb2.

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