scholarly journals Joint crystallization of KCuAl[PO4]2 and K(Al,Zn)2[(P,Si)O4]2: crystal chemistry and mechanism of formation of phosphate-silicate epitaxial heterostructure

2020 ◽  
Vol 76 (3) ◽  
pp. 483-491
Author(s):  
Olga Yakubovich ◽  
Galina Kiriukhina ◽  
Larisa Shvanskaya ◽  
Anatoliy Volkov ◽  
Olga Dimitrova
Keyword(s):  
Crystal Structures ◽  
Active Material ◽  
Structure Type ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrochemically Active ◽  
Phosphate Silicate ◽  
The Stability ◽  
Small Channels

Two novel phases, potassium copper aluminium bis(phosphate), KCuAl[PO4]2 (I), and potassium zinc aluminium bis(phosphate-silicate), K(Al,Zn)2[(P,Si)O4]2 (II), were obtained in one hydrothermal synthesis experiment at 553 K. Their crystal structures have been studied using single-crystal X-ray diffraction. (I) is a new member of the A + M 2+ M 3+[PO4]2 family. Its open 3D framework built by AlO5 and PO4 polyhedra includes small channels populated by columns of CuO6 octahedra sharing edges, and large channels where K+ ions are deposited. It is assumed that the stability of this structure type is due to the pair substitution of Cu/Al with Ni/Fe, Co/Fe or Mg/Fe in different representatives of the series. From the KCuAl[PO4]2 structural features, one may suppose it is a potentially electrochemically active material and/or possible low-temperature antiferromagnet. In accordance with results obtained from X-ray diffraction data, using scanning electron microscopy, microprobe analysis and detailed crystal chemical observation, (II) is considered as a product of epitaxial intergrowth of phosphate KAlZn[PO4]2 and silicate KAlSi[SiO4]2 components having closely similar crystal structures. The assembly of `coherent intergrowth' is described in the framework of a single diffraction pattern.

The crystal structures of α-Rb7Sb3Br16, α- and β-Tl7Bi3Br16 and their relationship to close packings of spheres

2020 ◽  
Vol 235 (8-9) ◽  
pp. 255-261 ◽  
Author(s):  
Jen-Hui Chang ◽  
Thomas Doert ◽  
Michael Ruck
Keyword(s):  
Aqueous Solutions ◽  
Crystal Structures ◽  
Structure Type ◽  
Structural Features ◽  
Close Packing ◽  
Stacking Sequence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pearson Symbol ◽  
Solvent Free Synthesis

AbstractYellow prismatic crystals of rubidium bromido-antimonate(III) Rb7Sb3Br16 and of two different modifications of thallium bromido-bismuthate(III) Tl7Bi3Br16 were obtained by solvent-free synthesis and by precipitation from acidic aqueous solutions. X-ray diffraction analyses revealed the Tl7Bi3I16-type for α-Tl7Bi3Br16 (orthorhombic, Cmcm, a = 2324.31(8) pm, b = 1346.69(4) pm, c = 3460.0(1) pm; Pearson symbol oC312) and a new structure type for β-Tl7Bi3Br16 (monoclinic, C2/c, a = 2331.87(5) pm, b = 1343.33(3) pm, c = 3546.01(7) pm, β = 102.708(1)°; mC312). The antimonate Rb7Sb3Br16 adopts the Tl7Bi3I16-type, too (orthorhombic, Cmcm, a = 2347.16(3) pm, b = 1357.89(5) pm, c = 3539.47(9) pm; oC312). The crystal structures of α- and β-Tl7Bi3Br16 comprise alternating slabs of isolated [BiBr6]3– octahedra and [Bi2Br10]4– octahedra pairs. Both structure types are hierarchically organized and can be regarded as sphere close packing with the same stacking sequence, if octahedra and octahedra pairs are replaced by spheres of equal size. The structural relationship between the Tl7Bi3I16-type and the hydrate Na7Bi3Br16 · 18H2O, which comprises similar structural features, is discussed.

Trigonal structures of ABe2BO3F2 (A = Rb, Cs, Tl) crystals

2009 ◽  
Vol 65 (4) ◽  
pp. 445-449 ◽  
Author(s):  
Colin D. McMillen ◽  
Jia Hu ◽  
Donald VanDerveer ◽  
Joseph W. Kolis
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Structure Type ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Higher Symmetry ◽  
Space Group ◽  
X Ray ◽  
Trigonal Structure

Several interesting fluoroberyllium borates were synthesized hydrothermally and characterized by single-crystal X-ray diffraction. The crystal structures of RbBe2BO3F2 (RBBF; rubidium fluoroberyllium borate) and CsBe2BO3F2 (CBBF; caesium fluoroberyllium borate), previously determined in the space group C2, were reinvestigated for higher symmetry and found to have more suitable solutions in the space group R32. TlBe2BO3F2 (TBBF; thallium fluoroberyllium borate) was synthesized as a novel compound also having this trigonal structure type. Details of the space-group determination and unique structural features are discussed. These crystal structures were compared with that of KBe2BO3F2, revealing interesting structural trends within this family of compounds that are also discussed. A crystallographic explanation of the physical morphology is postulated.

Die Kristallstrukturen der isotypen Verbindungen Ba3[MoN4] und Ba3[WN4] / The Crystal Structures of the Isotypic Compounds Ba3[MoN4] and Ba3[WN4]

1991 ◽  
Vol 46 (5) ◽  
pp. 566-572 ◽  
Author(s):  
Axel Gudat ◽  
Peter Höhn ◽  
Rüdiger Kniep ◽  
Albrecht Rabenau
Keyword(s):  
Transition Metals ◽  
Single Crystal ◽  
Crystal Structures ◽  
Structure Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ternary Compounds ◽  
The Third

The isotypic ternary compounds Ba3[MoN4] and Ba3[WN4] were prepared by reaction of the transition metals with barium (Ba3N2, resp.) under nitrogen. The crystal structures were determined by single crystal X-ray diffraction: Ba3[MoN4] (Ba3[WN4]): Pbca; Z = 8; a = 1083.9(3) pm (1091.8(3) pm), b = 1030.3(3) pm (1037.5(3) pm), c = 1202.9(3) pm (1209.2(4) pm). The structures contain isolated tetrahedral anions [MN4]6- (M = Mo, W) which are arranged in form of slightly distorted hexagonal layers and which are stacked along [010] with the sequence (···AB···). Two of the three Ba atoms are situated between, the third one is placed within the layers of [MN4]-groups. In this way the structures can be derived from the Na3As structure type.

scholarly journals Al5B12O25(OH) and Ga4InB12O25(OH) – two additional triel borates with the structure type M5B12O25(OH) (M = Ga, In)

2020 ◽  
Vol 75 (6-7) ◽  
pp. 605-613
Author(s):  
Daniela Vitzthum ◽  
Daniel S. Wimmer ◽  
Ingo Widmann ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Ir Spectroscopy ◽  
Single Crystal ◽  
Crystal Structures ◽  
Structure Type ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature

AbstractThe isotypic triel borates Al5B12O25(OH) and Ga4InB12O25(OH) were synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 12.0 GPa/1400 °C and 12.3 GPa/1200 °C, respectively. The crystal structures of both compounds, determined by single-crystal X-ray diffraction, constitute new representatives of the structure type M5B12O25(OH) (M = Ga, In) crystallizing in the space group I41/acd. The presence of the hydroxyl groups was confirmed via single-crystal IR spectroscopy.

Azide und Cyanamide – ähnlich und doch anders/Azides and Cyanamides – Similar and Yet Different

2003 ◽  
Vol 58 (11) ◽  
pp. 1097-1104 ◽  
Author(s):  
Olaf Reckeweg ◽  
Arndt Simon
Keyword(s):  
Ir Spectroscopy ◽  
Single Crystals ◽  
Crystal Structures ◽  
Spectroscopic Data ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time ◽  
Raman And Ir Spectroscopy

Abstract The crystal structures of LiN3*H2O (P63/mcm (No. 193), Z = 6; 924.01(13); 560.06(7) pm); NH4N3 (Pmna (No. 53), Z =4; a=889.78(18), b=380,67(8), c=867.35(17) pm); Ca(N3)2 (Fddd (No. 70), Z = 8; a=595.4(2), b=1103.6(5), c=1133.1(6) pm), Sr(N3)2 (Fddd (No. 70), Z =8; a= 612.02(9), b = 1154.60(18), c = 1182.62(15) pm); Ba(N3)2 (P21/m (No. 11), Z = 2; a = 544.8(1), b = 439.9(1), c = 961.3(2) pm, β = 99.64(3)°) and TlN3 (I4/mcm (No. 140), Z = 2; 618.96(9); 732.71(15) pm) have been either determined for the first time or redetermined by X-ray diffraction on single crystals. The afore mentioned compounds, AN3 (A = Na, K, Rb, Cs), M(N3)2 · 2.5 H2O (M = Mg, Zn) and the cyanamides Li2CN2, CdCN2 and CuCN2 were investigated by Raman and IR spectroscopy (KBr technique). Structural features and spectroscopic data of azides and cyanamides from this work and from literature are listed and compared.

In situelectrochemical high-energy X-ray diffraction using a capillary working electrode cell geometry

2017 ◽  
Vol 24 (4) ◽  
pp. 787-795 ◽  
Author(s):  
Matthias J. Young ◽  
Nicholas M. Bedford ◽  
Naisheng Jiang ◽  
Deqing Lin ◽  
Liming Dai
Keyword(s):  
Structural Changes ◽  
Active Material ◽  
High Energy ◽  
Distribution Functions ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Active Materials ◽  
X Ray ◽  
Working Electrode ◽  
Electrochemically Active

The ability to generate new electrochemically active materials for energy generation and storage with improved properties will likely be derived from an understanding of atomic-scale structure/function relationships during electrochemical events. Here, the design and implementation of a new capillary electrochemical cell designed specifically forin situhigh-energy X-ray diffraction measurements is described. By increasing the amount of electrochemically active material in the X-ray path while implementing low-Zcell materials with anisotropic scattering profiles, an order of magnitude enhancement in diffracted X-ray signal over traditional cell geometries for multiple electrochemically active materials is demonstrated. This signal improvement is crucial for high-energy X-ray diffraction measurements and subsequent Fourier transformation into atomic pair distribution functions for atomic-scale structural analysis. As an example, clear structural changes in LiCoO2under reductive and oxidative conditions using the capillary cell are demonstrated, which agree with prior studies. Accurate modeling of the LiCoO2diffraction data using reverse Monte Carlo simulations further verifies accurate background subtraction and strong signal from the electrochemically active material, enabled by the capillary working electrode geometry.

Die Kristallstrukturen von PPh4[SnCl3] und PPh4[SnBr3]/ The Crystal Structures of PPh4[SnCl3] and PPh4[SnBr3]

1982 ◽  
Vol 37 (9) ◽  
pp. 1122-1126 ◽  
Author(s):  
Ulrich Müller ◽  
Norbert Mronga ◽  
Christina Schumacher ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Vibrational Spectra ◽  
Diffraction Data ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Structure Determinations ◽  
The Ideal

AbstractPPh4[SnCl3] and PPh4[SnBr3] were prepared by reaction of PPh4X with SnX2 in CH2X2 solutions (X - Cl, Br). The vibrational spectra of the [SnX3]⊖ ions show three SnX3 stretching frequencies, which is caused by deviations from the ideal C3v symmetry. In the crystal structure determinations these deviations show up by slightly different Sn-X bond lengths which are explained by differing hydrogen bridges to phenyl-H atoms. The isotypic crystal structures of both compounds were determined and refined from X-ray diffraction data (R values: 0.042 and 0.034). Although triclinic (space group P1̄), the structures are closely related to the tetragonal AsPh4[RuNCl4] structure type. Very pure SnBr2 is prepared by the reaction of PPh4[SnBr3] with AlBr3 in CH2Br2 solution.

scholarly journals A Comparison of “Bottom-Up” and “Top-Down” Approaches to the Synthesis of Pt/C Electrocatalysts

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 947
Author(s):  
Alexandra Kuriganova ◽  
Nikita Faddeev ◽  
Mikhail Gorshenkov ◽  
Dmitri Kuznetsov ◽  
Igor Leontyev ◽  
...  
Keyword(s):  
Alternating Current ◽  
X Ray Diffraction ◽  
Platinum Nanoparticle ◽  
X Ray ◽  
Transmission Electron ◽  
Electrochemically Active ◽  
Electrochemical Dispersion ◽  
The Stability ◽  
Nanoparticle Sizes

Three 40 wt % Pt/C electrocatalysts prepared using two different approaches—the polyol process and electrochemical dispersion of platinum under pulse alternating current—and a commercial Pt/C catalyst (Johnson Matthey prod.) were examined via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The stability characteristics of the Pt/C catalysts were studied via long-term cycling, revealing that, for all cycling modes, the best stability was achieved for the Pt/C catalyst with the largest platinum nanoparticle sizes, which was synthesized via electrochemical dispersion of platinum under pulse alternating current. Our results show that the mass and specific electrocatalytic activities of Pt/C catalysts toward ethanol electrooxidation are determined by the value of the electrochemically active Pt surface area in the catalysts.

No solid solution compounds in between the binaries: syntheses and crystal structures of Nb(Br0.62(4)Cl0.38(4))2Cl2 and NbI2Cl2

2018 ◽  
Vol 73 (1) ◽  
pp. 29-34
Author(s):  
Olaf Reckeweg ◽  
Thomas Schleid
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
Crystal Structures ◽  
Site Occupancy ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Single Bonds

AbstractThe anion-mixed niobium tetrahalides Nb(Br0.62(4)Cl0.38(4))2Cl2 and NbI2Cl2 were obtained by heating NbBr5 with NbCl5 and NbI5 with NbCl5, respectively, in equimolar ratios with niobium metal in evacuated, torch-sealed silica ampoules at 720 K for 3 days. The orthorhombic title compounds form as very brittle black needles and were characterized by single-crystal X-ray diffraction [space group: Immm, Z=4; a=704.27(6), b=824.13(7), c=929.64(8) pm for Nb(Br0.62(4)Cl0.38(4))2Cl2 and a=753.76(6), b=829.38(7) and c=983.41(8) pm for NbI2Cl2]. Surprisingly enough, these mixed-anionic halides are not isostructural with either NbCl4, NbBr4 or NbI4, but crystallize isotypically with TaI2Cl2, thus being examples for differential site occupancy stabilized materials. Structural features of other niobium(IV) halides are compiled and compared to those of Nb(Br0.62(4)Cl0.38(4))2Cl2 and NbI2Cl2. Except for NbF4, they all exhibit chains of trans-edge connected [NbX6]2− octahedra, which allow Peierls distortions to form Nb–Nb single bonds. The packing of these chains differ, however, depending on the actual halide or mixed-halide combination.

M+M3+2As(HAsO4)6and α- and β-M+M3+(HAsO4)2(M+M3+= RbAl or CsFe): six new compounds crystallizing in three closely related structure types

2018 ◽  
Vol 74 (6) ◽  
pp. 721-727 ◽  
Author(s):  
Karolina Schwendtner ◽  
Uwe Kolitsch
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
General Formula ◽  
Structure Type ◽  
Group Symmetry ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stacking Order ◽  
New Compounds

The crystal structures of hydrothermally synthesized (T= 493 K, 7–9 d) rubidium aluminium bis[hydrogen arsenate(V)], RbAl(HAsO4)2, caesium iron bis[hydrogen arsenate(V)], CsFe(HAsO4)2, rubidium dialuminium arsenic(V) hexakis[hydrogen arsenate(V)], RbAl2As(HAsO4)6, and caesium diiron arsenic(V) hexakis[hydrogen arsenate(V)], CsFe2As(HAsO4)6, were solved by single-crystal X-ray diffraction. The four compounds with the general formulaM+M3+(HAsO4)2adopt the RbFe(HPO4)2structure type (R\overline{3}c) and a closely related new structure type, which is characterized by a different stacking order of the building units, leading to noncentrosymmetric space-group symmetryR32. The second new structure type, with the general formulaM+M3+2As(HAsO4)6(R\overline{3}c), is also a modification of the RbFe(HPO4)2structure type, in which one third of theM3+O6octahedra are replaced by AsO6octahedra, and two thirds of the voids in the structure, which are usually filled byM+cations, remain empty to achieve charge balance.

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