The Crystal Structure and Magnetic Property of Bi-Substituted Nd2Fe17-x-yTixSiy Intermetallic Compounds

2014 ◽  
Vol 644-650 ◽  
pp. 4950-4955 ◽  
Author(s):  
Li Mei Sun ◽  
Song Bai Han ◽  
Yun Tao Liu ◽  
Dong Feng Chen ◽  
Xiang Feng Liu
Keyword(s):  
Crystal Structure ◽  
Silicon Content ◽  
Unit Cell Volume ◽  
Magnetic Measurements ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Si Content ◽  
Ti Content

The synergetic effects of the substitution of Ti and Si for Fe on the crystallographic structure and magnetic properties of Nd2Fe17-x-yTixSiycompounds have been comprehensively investigated by means of x-ray diffraction, neutron diffraction and magnetic measurements. Rietveld refinements of the diffraction data indicate that all the samples crystallize in the rhombohedral Th2Zn17-type structure. For a given Ti content, thea-axis and the unit cell volumeVof Nd2Fe17-x-yTixSiydecrease linearly with increasing silicon content, while thec-axis behaves complicatedly dependent on different Ti content. The site occupancies of Ti and Si in the crystallographic sites significantly change compared to what is observed in the corresponding singly substituted compounds. TheTCof doubly substituted Nd2Fe16.5-yTi0.8Siyand Nd2Fe16.5-yTi0.5Siyis higher than that of singly substituted Nd2Fe16-ySiyfor a lower Si content while the converse behavior is observed for a higher Si content. For a given Ti content, theTCof Nd2Fe17-x-yTixSiycompounds increases with increasing Si content and theMsfirst increases and then decreases. TheMsof Nd2Fe17-x-yTixSiydecreases with the increase of Ti content.

Crystal-structure analysis of four mineral samples of anhydrite, CaSO4, using synchrotron high-resolution powder X-ray diffraction data

2011 ◽  
Vol 26 (4) ◽  
pp. 326-330 ◽  
Author(s):  
Sytle M. Antao
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Unit Cell Volume ◽  
Crystal Structure Analysis ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cell Parameters

The crystal structures of four samples of anhydrite, CaSO4, were obtained by Rietveld refinements using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and space group Amma. As an example, for one sample of anhydrite from Hants County, Nova Scotia, the unit-cell parameters are a = 7.00032(2), b = 6.99234(1), c = 6.24097(1) Å, and V = 305.487(1) Å3 with a > b. The eight-coordinated Ca atom has an average <Ca-O> distance of 2.4667(4) Å. The tetrahedral SO4 group has two independent S-O distances of 1.484(1) to O1 and 1.478(1) Å to O2 and an average <S-O> distance of 1.4810(5) Å. The three independent O-S-O angles [108.99(8) × 1, 110.38(3) × 4, 106.34(9)° × 1; average <O-S-O> [6] = 109.47(2)°] and S-O distances indicate that the geometry of the SO4 group is quite distorted in anhydrite. The four anhydrite samples have structural trends where the a, b, and c unit-cell parameters increase linearly with increasing unit-cell volume, V, and their average <Ca-O> and <S-O> distances are nearly constant. The grand mean <Ca-O> = 2.4660(2) Å, and grand mean <S-O> = 1.4848(3) Å, the latter is longer than 1.480(1) Å in celestite, SrSO4, as expected.

scholarly journals Structural Variations across Wolframite Solid Solutions, (Fe,Mn)WO4

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 42
Author(s):  
Darren A. Umbsaar ◽  
Sytle M. Antao
Keyword(s):  
Crystal Structure ◽  
Solid Solutions ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Structural Variations ◽  
Unit Cell Parameters ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cell Parameters

The crystal structure of four samples from natural wolframite solid solutions, (Fe,Mn)WO4, was obtained with synchrotron high-resolution powder X-ray diffraction (HRPXRD) data, Rietveld refinements, space group P2/c, and Z = 2. Wolframite solid solutions extend from ferberite (FeWO4) to hübnerite (MnWO4). The W and (Mn,Fe) cations are in six-fold coordination. This study shows that the unit-cell parameters, a, b, c, and β angle, vary linearly with the unit-cell volume, V, across the wolframite series. The average <Mn,Fe–O> distance increases linearly because of larger Mn2+ (0.83 Å) replacing smaller Fe2+ (0.78 Å) cations, whereas the average <W–O> distance increases slightly because of the higher effective charge of the smaller Fe2+ cation. The distortions of the two types of polyhedra across the series are discussed.

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.

Synthesen, Kristallstrukturen und magnetische Eigenschaften von [Li(12-Krone-4)2][Li(12-Krone-4)(OH2)]2[Nb6Cl18], [Li(15-Krone-5)2(OH2)]3[Nb6Cl18] und [(18-Krone-6)2(O2H5)]3[Nb6Cl18] / Syntheses, Crystal Structures and Magnetic Behaviour of [Li(12-Krone-4)2][Li(12-Krone-4)(OH2)]2[Nb6Cl18], [Li(15-Krone-5)2(OH2)]3[Nb6Cl18] and [(18-Krone-6)2(O2H5)]3[Nb6Cl18]

2001 ◽  
Vol 56 (10) ◽  
pp. 1025-1034 ◽  
Author(s):  
Markus Ströbele ◽  
H.-Jtirgen Meyer
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Crown Ethers ◽  
Magnetic Measurements ◽  
Structure Refinement ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Paramagnetic Behaviour

The title compounds were prepared through reactions of Li2Nb6Cl16 with the corresponding crown ethers in acetone. All three compounds were obtained as dark brown crystals. Their structures were solved with the means of single-crystal X-ray diffraction.[Li(12-crown-4)2][Li(12-crown-4)(OH2)]2[Nb6Cl18]: space group P21/n, Z =2, a = 1320.4(1), b = 1879.1(1), c = 1321.7(1) pm, ß = 92.515(6)°, R1 = 0.0297 (I>2σ(I)). The crystal structure contains Li+ sandwiched by two 12-crown-4-ethers plus Li+ coordinated by one 12-crown-4- ether and one water molecule.[Li(15-crown-5)2(OH2)]3[Nb6Cl18]: space group R3̅, Z = 3, a = b = 2081.7(1), c = 1991.7(1) pm, R1 = 0.0395 (I > 2σ(I)). In the crystal structure Li+ and one water molecule are sandwiched by two 15-crown-5-ethers.[(18-crown-6)2(O2H5)]3[Nb6Cl18]: space group P1̅, Z = 1 ,a = 1405.1(1), b = 1461.1(2), c = 1492.2(2) pm; α = 98.80(1)°, ß = 98.15(1)°, γ = 97.41(1)°, R1 = 0.0538 (I > 2σ(I)). H5O2+ was found in the structure refinement sandwiched between two 18-crown-6-ethers.All compounds reported contain [Nb6Cl18] clusters with Nb-Nb distances between 299 and 301 pm. The paramagnetic behaviour expected for [Nb6Cl18]3- in all three compounds was confirmed by magnetic measurements.

Rietveld Studies on Silicon Substituted Hydroxyapatite

2006 ◽  
Vol 309-311 ◽  
pp. 113-116 ◽  
Author(s):  
Shuo Zou ◽  
Jie Huang ◽  
Serena Best ◽  
William Bonfield
Keyword(s):  
Silicon Content ◽  
Sintering Temperature ◽  
Silicon Concentration ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Phase Purity ◽  
X Ray ◽  
Similar Dependence ◽  
Initial Silicon ◽  
Distortion Index

Silicon-substituted hydroxyapatite (SiHA) attracts particular interest due its enhanced bioactivity compared with pure hydroxyapatite. In this study we seek to clarify the effects on the lattice parameters of both composition and sintering temperature in experimentally-produced HA and 0.8wt% SiHA, 1.5wt% SiHA and 2.0wt% SiHA sintered at 800oC and 1200oC. X ray diffraction was used to determine the phase purity and crystallographic structure. We found that while the c parameter increased with increasing silicon concentration, the a parameter decreased with initial silicon incorporation then recovered with further increases in silicon incorporation. The calcium (2) channel expanded with silicon incorporation while tetrahedron distortion index (TDI) and the radius of the P channel showed a similar dependence on silicon content as the a parameter.

Study on Novel Structure of Potassium Borate Hydrate: K(H4B5O10)·2(H2O)

2012 ◽  
Vol 531-532 ◽  
pp. 409-412
Author(s):  
Hai Xing Liu ◽  
Fang Fang Jian ◽  
Jing Wang ◽  
Guang Zeng ◽  
Hui Juan Yue ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Packing ◽  
Three Dimensional ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Potassium Borate ◽  
Polyhydroxy Compounds ◽  
Novel Structure ◽  
Solution Reaction

Numerous stable complexes of boric acid with polyhydroxy compounds, including tartaric, salicylic, citric, malic, and other acids, are known. The structure of some compounds contains polyanion. In this paper, a novel potassium borate hydrate [K(H4B5O10) •2(H2O)] has been synthesized from a solution reaction and the crystal structure has been determined by means of single-crystal X-ray diffraction. Orthorhombic, Aba2. a = 11.0781(14) Å b = 11.1780(15) Å c = 9.0508(11) Å α=β=γ=90°. V= 1120.8(2) Å3. Z=4. Rgt = 0.0244, wRref = 0.0623. T= 298 K. The crystal packing is stabilized by O-H...O hydrogen bonds interaction and three dimensional framwork structure is formed. The work is originality and has a new crystallographic structure shape.

scholarly journals A New Modification of Rb[Al(NH2)4] and Condensation in Solid State

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1018
Author(s):  
Christian Bäucker ◽  
Rainer Niewa
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structural Modification ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
Surrounding Area ◽  
Rietveld Refinements ◽  
X Ray ◽  
The Third ◽  
Infrared And Raman Spectroscopy

A new modification of Rb[Al(NH2)4] in space group C2/c, which differs from the known structural modification in the way the [Al(NH2)4]−-tetrahedra are arranged in the surrounding area of the rubidium cation, was obtained from ammonothermal synthesis at 673 K and 680 bar. The crystal structure was determined by Rietveld refinements and further investigated by infrared and Raman spectroscopy. Thermal gravimetric investigations indicate two decomposition steps up to 450 °C, which can be assigned to ammonia leaving the material while the sample liquefies. During the third and final step, volatile rubidium amide is released, leaving nano-scaled cubic AlN behind. Investigating differently aged samples implies decomposition and condensation of amidoaluminate ions already at ambient temperature, which is supported by refinements of single crystal X-ray diffraction data, revealing lower nitrogen amounts than expected. The observed single crystal also exhibits a significantly smaller volume than the reported structures, further supporting the decomposition–condensation mechanism.

Crystal Structure of Tris(1,10-phenanthroline)mercury(II) Trifluoromethanesulfonate

1979 ◽  
Vol 32 (10) ◽  
pp. 2195 ◽  
Author(s):  
GB Deacon ◽  
CL Raston ◽  
D Tunaley ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Title Compound ◽  
Unit Cell Volume ◽  
Octahedral Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ethanol Solvate ◽  
The Mean ◽  
Trigonal Prismatic

The crystal structure of the ethanol solvate of the title compound, [Hg(phen)3](CF3S03)2 (phen =1,10-phenanthroline), has been determined at 295(1) K by single-crystal X-ray diffraction and refined by least squares to a residual of 0�043 for 2939 'observed' reflections. Crystals are monoclinic: C2/c, a 25�25(1), b 10�960(4), c 18�949(6) �, β 129�32(2)�, Z 4. The cation is centred on a crystallographictwofold axis and has approximate D3 point symmetry. The deviation of the mercury(II) environment from octahedral symmetry toward the trigonal-prismatic limit is considerable, the mean trans N-Hg-N angle being 154�52�. <Hg-N> is 2�400 �. The unit cell volume is considerablydependent on crystallization solvent, being larger for the ethanol solvate than for solvent-free crystals obtained from aqueous solution.

Crystal structure of low-cristobalite-type Al0.5Ga0.5PO4: A combined Rietveld refinement of neutron and X-ray diffraction data

2005 ◽  
Vol 20 (3) ◽  
pp. 207-211 ◽  
Author(s):  
S. N. Achary ◽  
A. K. Tyagi ◽  
S. K. Kulshreshtha ◽  
O. D. Jayakumar ◽  
P. S. R. Krishna ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Tetrahedral Coordination ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cell Parameters ◽  
Bond Lengths

The low-cristobalite-type modification of Al0.5Ga0.5PO4 is prepared by annealing the amorphous precipitate of stoichiometric phosphate at 1300 °C. The phase purity of the sample is ascertained by powder X-ray diffraction. The crystal structure is refined by Rietveld refinements of the neutron and X-ray diffraction data of the polycrystalline powder. This compound crystallizes in an orthorhombic lattice with unit cell parameters, a=7.0295(8), b=7.0132(8), and c=6.9187(4) Å, V=341.08(6) Å3, Z=4 (Space group C 2221, No. 20). The crystal structure analysis reveals the random distribution of the Al3+ and Ga3+ having tetrahedral coordination with typical M–O (M=Al3+:Ga3+) bond lengths as 1.74 Å. Similarly, the P5+ have tetrahedral coordination with typical P–O bond lengths 1.52–1.54 Å. The Mo4 and PO4 tetraheda are linked by common corners forming a three-dimensional framework lattice. The details of the crystal structure are presented in this paper.

Synthesis, crystal structure, and magnetic properties of a multicage compound: [(Me)2EtNH][Mn(N3)3] with a perovskite-related structure

2019 ◽  
Vol 74 (4) ◽  
pp. 335-339 ◽  
Author(s):  
Jie Yang ◽  
Yuan Huang ◽  
Ting Fang ◽  
Kun Qian ◽  
Wen-Bin Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Magnetic Measurements ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Related Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polar Crystal

AbstractA new multicage compound [(Me)2EtNH][Mn(N3)3] (Me = methyl, Et = ethyl) with a perovskite-related structure has been synthesized. The manganese(II) cations are bridged by end-to-end (EE) azide anions to form three-dimensional cages with the N,N-dimethylethylammonium cations residing in the cavities of the [Mn(N3)3]nn− cages. The compound has been characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, second-harmonic generation, and magnetic measurements. The second-harmonic generation results support its noncentrosymmetric polar crystal structure. Magnetic susceptibility measurements show antiferromagnetic interactions among the MnII ions.

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