scholarly journals Crystal structure and Mössbauer study of FeAl2O4

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 47-49 ◽  
Author(s):  
Ilona Jastrzębska ◽  
Jacek Szczerba ◽  
Paweł Stoch ◽  
Artur Błachowski ◽  
Krzysztof Ruebenbauer ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Spinel Structure ◽  
Approximate Formula ◽  
Argon Atmosphere ◽  
Mossbauer Effect ◽  
Mössbauer Study ◽  
Melting Method ◽  
X Ray ◽  
Octahedral Sites ◽  
Arc Melting

Abstract In this work the synthesis of hercynite from Fe2O3 and Al2O3 powders was carried out by arc-melting method under the protective argon atmosphere. The obtained material was characterized with the use of powder X-ray diffractometry (XRD) and Mössbauer spectroscopy (MS). A Mössbauer effect in hercynite obtained by the arc-melting method indicated the cations distribution in the spinel structure among the tetrahedral and octahedral interstices. The presence of Fe2+ ions was detected in both tetrahedral and octahedral sites while Fe3+ ions occupied only the octahedral interstices. The approximate formula of the obtained iron-aluminate spinel was as follows (Fe2+0.77Al3+0.23) (Fe3+0.07Fe2+0.05Al0.88)2O4.

The X-Ray Powder Diffraction Patterns and Crystal Structure for Al2M3Y(M=Cu, Ni)

2014 ◽  
Vol 950 ◽  
pp. 48-52
Author(s):  
De Gui Li ◽  
Ming Qin ◽  
Liu Qing Liang ◽  
Zhao Lu ◽  
Shu Hui Liu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Hexagonal Structure ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Arc Melting ◽  
Diffraction Patterns

The Al2M3Y(M=Cu, Ni) compound was synthesized by arc melting under argon atmosphere. The high-quality powder X-ray diffraction data of Al2M3Y have been presented. The refinement of the X-ray diffraction patterns for the Al2M3Y compound show that the Al2M3Y has hexagonal structure, space groupP6/mmm(No.191), with a = b = 5.1618(2) Å, c = 4.1434(1) Å,V= 95.6 Å3,Z= 1,ڑx= 5.7922 g/cm3,F30= 155.5(0.0057, 34), RIR = 2.31 for Al2Cu3Y, and with a = b = 5.0399(1) Å, c = 4.0726(1) Å,V= 89.59 Å3,Z= 1,ڑx= 5.9118 g/cm3,F30= 135.7(0.0072, 30), RIR = 2.54 for Al2Ni3Y.

Crystal structure and X-ray powder diffraction pattern of Ti2ZrAl

2000 ◽  
Vol 15 (3) ◽  
pp. 189-190 ◽  
Author(s):  
D. Sornadurai ◽  
B. Panigrahi ◽  
V. S. Sastry ◽  
Ramani
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Single Phase ◽  
Xrd Analysis ◽  
Melting Method ◽  
X Ray ◽  
Structure Space ◽  
Arc Melting ◽  
Phase Pure

We report precision X-ray powder-diffraction (XRD) data of single phase pure Ti2ZrAl. Ti2ZrAl samples were prepared by an arc melting method and annealed at 1000 °C for 30 days. XRD analysis was carried out on these samples and it was found that Ti2ZrAl has a DO19 structure (space group P63/mmc, No. 194). The lattice parameters are found to be a=5.961±0.001 Å and c=4.793±0.001 Å.

Crystal Structure of Al2Cu3Nd Ternary Compound

2016 ◽  
Vol 850 ◽  
pp. 8-12
Author(s):  
De Gui Li ◽  
Liu Qing Liang ◽  
Ming Qin ◽  
Lei Hu ◽  
Chang Sheng Qin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ternary Compound ◽  
Hexagonal Structure ◽  
Argon Atmosphere ◽  
System Alloy ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Arc Melting ◽  
Diffraction Peaks

A new Al-Cu-Nd system alloy, the high-purity Al2Cu3Nd ternary compound, was developed and prepared with the stoichiometric amounts of elemental constituents by arc melting under argon atmosphere. The X-ray diffraction (XRD) data of Al2Cu3Nd was collected by using the Rigaku Smart Lab X-ray powder diffractometer, and all X-ray diffraction peaks of Al2Cu3Nd compound were indexed successfully with the hexagonal structure. The Rietveld refinement results of the XRD pattern for the Al2Cu3Nd compound showed that the Al2Cu3Nd compound is the hexagonal structure, space group P6/mmm (No.191) with a = 5.2397(1) Å, c = 4.1783(1) Å, V = 99.34 Å3, Z = 1. The density of the compound was 6.501 g/cm3, and its reference intensity ratio (RIR) w 1.26.

Aging of iron manganite negative temperature coefficient thermistors

1998 ◽  
Vol 13 (5) ◽  
pp. 1238-1242 ◽  
Author(s):  
T. Battault ◽  
R. Legros ◽  
A. Rousset
Keyword(s):  
Temperature Coefficient ◽  
Spinel Structure ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Octahedral Sites ◽  
Before And After ◽  
Structural Equilibrium ◽  
Electrical Data

“Aging,” defined as the drift of resistance with temperature after 1000 h, was investigated for iron manganite temperature coefficient thermistors. For these devices, aging is relatively large, about 10%. The cationic distributions before and after aging were determined by Mössbauer spectroscopy. These distributions explain all the x-ray diffraction and correlated electrical data. The origin of the aging observed on iron manganites thermistors has been identified. It is due to the migration of Fe3+ ions from tetrahedral to octahedral sites of the spinel structure in order to reach a structural equilibrium.

scholarly journals CRYSTAL STRUCTURE OF THE NEW SILICIDE Lu3Ni11.74(2)Si4

2020 ◽  
Vol 86 (5) ◽  
pp. 3-12
Author(s):  
Bohdana Belan ◽  
Mykola Manyako ◽  
Mariya Dzevenko ◽  
Dorota Kowalska ◽  
Roman Gladyshevskii
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Arc Melting ◽  
Pearson Symbol ◽  
Ternary Silicide

The new ternary silicide Lu3Ni11.74(2)Si4 was synthesized from the elements by arc-melting and its crystal structure was determined by the single-crystal X-ray diffraction. The compound crystallizes in the Sc3Ni11Ge4-type: Pearson symbol hP37.2, space group P63/mmc (No. 194), a = 8.0985(16), c = 8.550(2) Å, Z = 2; R = 0.0244, wR = 0.0430 for 244 reflections. The silicide Lu3Ni11.74(2)Si4 is new member of the EuMg5.2-type structure family.

Crystal Structure of the Dy3Ni11.83Si3.98 Compound

2019 ◽  
Vol 289 ◽  
pp. 77-81
Author(s):  
Bohdana Belan ◽  
Mykola Manyako ◽  
Katarzyna Pasinska ◽  
Marta Demchyna ◽  
Roman E. Gladyshevskii
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Large Family ◽  
Type Structure ◽  
Single Crystal Diffraction ◽  
Space Group ◽  
X Ray ◽  
Arc Melting ◽  
Pearson Symbol ◽  
Ternary Silicide

The new ternary silicide Dy3Ni11.83(1)Si3.98(1)was synthesized from the elements by arc-melting and its crystal structure was determined by X-ray single-crystal diffraction. The compound crystallizes in a Sc3Ni11Ge4-type structure: Pearson symbolhP38, space groupP63/mmc(No. 194),a= 8.1990(7),c= 8.6840(7) Å,Z= 2;R= 0.0222, wR= 0.0284 for 365 reflections. The structure belongs to a large family of structures related to the EuMg5.2type, with representatives among ternary aluminides, silicides, germanides,etc.

Crystal structure of coalingite

1971 ◽  
Vol 38 (295) ◽  
pp. 286-294 ◽  
Author(s):  
J. Pastor-Rodriguez ◽  
H. F. W. Taylor
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Water Molecules ◽  
Structural Elements ◽  
Structural Element ◽  
X Ray ◽  
Octahedral Sites ◽  
Carbonate Ions ◽  
Disordered Layer ◽  
Ray Methods

SummaryThe crystal structure of coalingite (Mg10Fe2(OH)24(CO3)·2H2O) has been determined using single-crystal X-ray methods. The mineral is trigonal, with space group Rm, aH = 3·12, cH = 37·4 Å, Z = ½, and (0001) cleavage. The structure is of a layer type, and is based on a structural element about 12·5 Å thick in the c-direction and consisting of two brucite-like layers and one disordered layer containing carbonate ions and water molecules and resembling those in sjögrenite and pyroaurite. The unit cell comprises three of these structural elements stacked together in the c-direction. The Mg2+ and Fe3+ ions are randomly distributed among all the octahedral sites of the brucite-like layers. The structure closely resembles those of sjögrenite and pyroaurite, but has two brucite-like layers between each CO32−−H2O layer where these have one. There is a tendency to random interstratification, and the crystals appear to contain intergrown regions of brucite and of sjögrenite or pyroaurite. Coalingite-K probably has a similar structure, but with three brucite-like layers between each -H2O layer; its idealized formula is probably Mg16Fe2(OH)36(CO3).2H2O.

scholarly journals Crystal structure of Ni-sorbed synthetic vernadite: a powder X-ray diffraction study

2008 ◽  
Vol 72 (6) ◽  
pp. 1279-1291 ◽  
Author(s):  
S. Grangeon ◽  
B. Lanson ◽  
M. Lanson ◽  
A. Manceau
Keyword(s):  
Crystal Structure ◽  
Coherent Scattering ◽  
Layer Charge ◽  
Layer Plane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Octahedral Sites ◽  
Ph Values ◽  
Oceanic Sediments ◽  
Ni Uptake

AbstractVernadite is a nanocrystalline turbostratic phyllomanganate containing Ni, and is widespread in surface environments and oceanic sediments. To improve our understanding of Ni uptake in this mineral, two series of analogues of vernadite (δ-MnO2) were prepared with Ni/Mn atomic ratios of 0.002—0.105 at pH4 and 0.002—0.177 at pH 7. Their structures were characterized using X-ray powder diffraction (XRD). The δ-MnO2 nano-crystals are essentially monolayers with coherent scattering domains sizes of ∼10 Å perpendicular to the layering and ∼55 Å within the layer plane. For Ni/Mn < 0.01, the layer charge deficit is apparently balanced entirely by interlayer Mn, Na and protons. At higher Ni/Mn, Ni occupies the same site as interlayer Mn above and below vacant sites within the MnO2 layer and at sites along the edges of the layer. However, the layer charge is balanced differently at the two pH values. At pH 4, Ni uptake is accompanied by a reduction in structural Na and protons, whereas interlayer Mn remains strongly bound to the layers. At pH 7, interlayer Mn is less strongly bound and is partially replaced by Ni. The results of this study also suggest that the number of vacant octahedral sites and multi-valent charge-copmpensating interlayer species are underestimated by the currently used structure models of δ-MnO2.

Preparation, Crystal Structure, and Properties of the Lanthanoid Carbides Ln4C7 with Ln = Ho, Er, Tm, and Lu

1996 ◽  
Vol 51 (5) ◽  
pp. 646-654 ◽  
Author(s):  
Ralf Czekalla ◽  
Wolfgang Jeitschko ◽  
Rolf-Dieter Hoffmann ◽  
Helmut Rabeneck
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Magnetic Ordering ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Neutron Powder Diffraction Data ◽  
Monoclinic Crystal Structure ◽  
Arc Melting ◽  
Structure Factors ◽  
Hydrolysis Of

The isotypic carbides Ln4C7 (Ln = Ho, Er, Tm, Lu) were prepared by arc-melting of the elemental components, followed by annealing at 1300 °C. The positions of the metal and of some carbon atoms of the monoclinic crystal structure of LU4C7 were determined from X-ray powder data, and the last carbon positions were found and refined from neutron powder diffraction data: P21/c, a = 360.4(1), b = 1351.4(3), c = 629.0(2) pm, β = 104.97(2)°, Z = 2, R = 0.026 for 429 structure factors and 15 positional parameters. The structure contains isolated carbon atoms with octahedral lutetium coordination and linear C3-units, with C-C bond lengths of 132(1) and 135(1) pm. This carbide may therefore be considered as derived from methane and propadiene. The hydrolysis of LU4C7 with distilled water yields mainly methane and propine, while the hydrolyses of the corresponding holmium and erbium carbides resulted in relatively large amounts of saturated and unsaturated C2-hydrocarbons in addition to the expected products methane and propine. The structure comprises two-dimensionally infinite NaCl-type building elements, which are separated by the C3-units. It may be described as a stacking variant of a previously reported structure of HO4C7, now designated as the a-modification. The Lu4C7-type β -modification was obtained at higher temperatures. Its structure was refined by the Rietveld method from X-ray powder data to a residual R = 0.037 for 320 F values and 15 positional parameters. Lu4C7 is Pauli paramagnetic; β -HO4C7 and Er4C7 show Curie-Weiss behavior with magnetic ordering temperatures of less than 20 K.

Kristall- und elektronische Struktur von LaAlSi2 / Crystal and Electronic Structure of LaAlSi2

2001 ◽  
Vol 56 (7) ◽  
pp. 620-625 ◽  
Author(s):  
Christian Kranenberg ◽  
Dirk Johrendt ◽  
Albrecht Mewis ◽  
Winfried Kockelmann
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Neutron Diffraction ◽  
Structure Type ◽  
X Ray ◽  
Arc Melting ◽  
Band Structure Calculations ◽  
Ray Methods ◽  
Structure Calculations ◽  
Crystal And Electronic Structure

Abstract LaAlSi2 (a = 4.196(2), c = 11.437(7) Å; P3̄ml; Z = 2) was synthesized by arc-melting of preheated mixtures of the elements. The compound was investigated by means of X-ray methods and by neutron diffraction. The crystal structure can be described as a stacking variant of two different segments. The first one corresponds to the CaAl2Si2 structure type (LaAl2Si2), the second one with the A1B2 structure type (LaSi2). The segments are stacked along [001]. The electronic structure of the compound is discussed on the basis of LMTO band structure calculations.

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