Crystal structure and characterization of [2,5-(CH3O)2C6H3NH3]4P4O12·2H2O

The preparation, crystal structure, TG–DTA analysis and spectroscopy investigation are reported for the 2,5-dimethoxy phenyl ammonium cyclotetraphosphate dihydrate [2,5-(CH₃O)₂C₆H₃NH₃]₄P₄O₁₂·2H₂O. This new compound is triclinic P with unit cell dimensions: a = 7.438(5) Å, b = 11.841(7) Å, c = 12.354(4) Å,  = 96.61(4)°, β = 98.35(4)°, γ = 102.60(6)°, Z = 1 and V = 1038.0(1) Å³. Its crystal structure has been determined and refined to R = 0.049, with 5128 independant reflections. The structure can be described by rows of P₄O₁₂ ring anions along the a axis; between these rows are located the organic groups, connected to them by hydrogen bonds.     

Synthesis and crystal structure of [2-NH2-5-CH3C5H4N]4P4O12·6H2O

Chemical preparation, crystal structure, IR absorption and thermal analysis of a new cyclotetraphosphate [2-NH₂-5-CH₃C₅H₄N]₄P₄O₁₂·6H₂O are reported. This compound is triclinic P-1 with unit-cell parameters: a = 10.206(5), b = 11.778(1), c = 9.991(4) Å,  = 110.40(6), β = 117.74(6), γ = 86.41(3)°, V = 989.1(8) Å³, Z = 1, D_x = 1.445 g cm⁻³. The structure has been determined and refined to R = 0.034 and R_w = 0.044, using 3663 independent reflections. The ring anions and water molecules form layers spreading around (a, b + c) planes via OHO hydrogen bonds. Between them are anchored 2-amino-5-methylpyridium cations, which establish H-bonds to interconnect the different adjacent layers and so contribute to the cohesion of the three-dimensional network. Tautomerization of (C₆H₉N₂)⁺ groups was evidenced in the present structure.     

Synthesis and crystal structure of [3,5-(CH3O)2C6H3NH3]4P4O12·4H2O

The chemical preparation and crystal structure are given for a new organic-cation cyclotetraphosphate. This compound is triclinic P-1 with the following unit cell parameters: a=7.857(1) Å, b=8.877(2) Å, c=17.271(3) Å, α=93.94(1)°, β=101.75(2)°, γ=103.72(1)° V=1137.0(4) Å³, Z=1 and ρ_cal=1.467 g cm⁻³. The crystal structure has been determined and refined to R=0.037, using 6291 independent reflections. The atomic arrangement can be described by inorganic layers parallel to the (0 0 1) planes, between which the organic entities are located.     

Crystal structure of a new organic condensed phosphate (C6H9N3O)H2P2O7

Crystals of a new organic compound, the isonicotinic acid hydrazide dihydrogendiphosphate, (C₆H₉N₃O)H₂P₂O₇ (denoted INHDP) were prepared and grown at room temperature. The INHDP crystallizes in the triclinic system with the space group. Its unit cell dimensions are: a = 7.316(3) Å, b = 7.783(3) Å, c = 10.802(4) Å, α = 82.41(3)°, β = 75.19(3)°, γ = 72.57(3)°, with V = 566.3(4) Å³ and Z = 2. Crystal structure has been determined and refined to a reliability R factor of 0.0389. The atomic arrangement can be described as inorganic infinite ribbons of H₂P₂O₇²⁻ anions spreading parallel to the b-axis. These ribbons are themselves interconnected by the organic (C₆H₉N₃O)⁺ cations so as to build a three dimensional arrangement. In the present work, we describe the crystal structure, thermal behaviour and IR analysis of this new compound.     

Crystal structures, thermal analysis and IR investigations of (C4H14N2O)SO4 and (C4H14N2O)SO4·H2O

Crystals of 2(2-ammonium ethyl ammonium)ethanol sulfate monohydrate: (C₄H₁₄N₂O)SO₄·H₂O abbreviated as AEESM, and 2(2-ammonium ethyl ammonium)ethanol sulfate: (C₄H₁₄N₂O)SO₄ abbreviated as AEES, have been prepared and grown at room temperature. These materials have the following unit cell dimensions (C₄H₁₄N₂O)SO₄·H₂O: a = 16.116(6), b = 7.411(3), and c = 15.750(6) Å; (C₄H₁₄N₂O)SO₄: a = 8.1142(2), b = 10.6632(4), c = 9.9951(4) Å, and β = 99.433(3)°. Their space groups are Pbca and P2₁/c, respectively. The structures of these compounds have been determined by single-crystal X-ray data analysis. The AEESM structure is built up from infinite inorganic chains parallel to the b axis linked via Ow-H?O hydrogen bonds. These chains are interconnected by organic groups so as to build layers perpendicular to the c direction. The structure of AEES consists of a three-dimensional network of H-bonds connecting all its components. In the present work the crystal structures, thermal behavior and IR analysis of these two new compounds are described.     

Synthesis and characterization of a new 2,4,6-triaminopyridinium dihydrogendiphosphate dihydrate (C4H8N5)2H2P2O7·2H2O

Structural properties of the 2,4,6-triaminopyridinium dihydrogendiphosphate dihydrate are discussed on the basis of an X-ray structure investigation. (C₄H₈N₅)₂H₂P₂O₇·2H₂O is monoclinic, C2/c, with a = 10.414(1) Å, b = 13.365(1) Å, c = 13.736(2) Å, β = 98.39(4)°, and Z = 4. The structure has been solved by a direct method and refined to a reliability R factor of 0.0375 (R_w = 0.0961) using 2751 independent reflections. The structural arrangement can be described as inorganic infinite ribbons, , spreading along the c direction; the organic groups, [C₄H₈N₅]⁺, link the precedent ribbons, via their hydrogen bonds, to form a three-dimensional network. The present work, deals with crystal structure, thermal behavior and IR analysis of this new compound.     

A new iron lead vanadate Pb2FeV3O11: Synthesis and some properties

A new iron lead vanadate, Pb₂FeV₃O₁₁, has been obtained. It melts incongruently at 650 ± 5 °C depositing two solid phases: Pb₂V₂O₇ and Fe₂O₃. Pb₂FeV₃O₁₁ crystallises in the monoclinic system. The infra-red spectrum and images of the new phase obtained by means of an electron scanning microscope are presented.     

Synthesis and characterization of the open-framework cobalt borophosphate: (C4N2H12)Co[B2P3O12(OH)]

A high yield hydrothermal synthesis of the open-framework cobalt borophosphate (C₄N₂H₁₂)Co[B₂P₃O₁₂(OH)], has been developed. The compound was characterized by single crystal X-ray diffraction methods, thermogravimetric analysis, vibrational (IR and Raman) spectroscopy and magnetic measurements. In the structure Co(II)O₆ octahedra, BO₄ and PO₄ tetrahedra form nine-member rings which in turn are linked to form CoBPO layers parallel to the bc plane. The layers are joined together by another set of PO₄ tetrahedra and the (piperazinium)²⁺ cations occupy the channels running along [1 0 0]. The structure is compared with that of (C₂N₂H₁₀)Co[B₂P₃O₁₂(OH)].     

Crystal structure and physicochemical properties of a new organic condensed phosphate (C7H10NO)3P3O9·4H2O

Chemical preparation, X-ray characterization, IR spectroscopy and thermal analysis of a new cyclotriphosphate: (C₇H₁₀NO)₃P₃O₉·4H₂O abbreviated as OACTP, are reported. This mixed organo-mineral compound crystallizes in the monoclinic system with P2₁/n space group, the unit cell dimensions are: a = 6.605(3) Å, b = 26.166(3) Å, c = 18.671(8) Å, β = 91.95(3)°, Z = 4 and V = 3255(2) Å³. The structure was solved using a direct method and refined to a reliability R-factor of 0.043 using 3931 independent reflections (I > 2σI). Atomic arrangement exhibits infinite (P₃O₉·2H₂O)_n³ⁿ⁻ chains connected by organic cations. The thermal behavior and the IR spectroscopic studies of this new compound are discussed.     

Synthesis and characterization of nanocrystalline MgAl2O4 spinel via sucrose process

Nanocrystalline MgAl₂O₄ spinel powder was synthesized using metal nitrates and a polymer matrix precursor composed of sucrose and polyvinyl alcohol (PVA). The precursor and the calcined powders were characterized by simultaneous thermal analysis (STA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). According to XRD results, the inceptive formation temperature of spinel via this technique was between 600 and 700 °C. The calcined powder at 800 °C for 2 h has faced shaped morphology and its crystallite size is in the range of 8-12 nm. Further studies also showed that the amount of polymeric matrix to metal ions has significant influence on the crystallite size of synthesized magnesium aluminate spinel powder.     

Synthesis and crystal structure of Cu2NiO(B2O5) and Cu2MgO(B2O5)

A transport reaction synthesis technique has been used to prepare single crystals of two pyroborate compounds having the formulas Cu₂NiO(B₂O₅) and Cu₂MgO(B₂O₅). The two compounds are isostructural and crystallize in the monoclinic space group P2₁/c. Cu₂NiO(B₂O₅): a=3.2003(10), b=14.775(3), c=9.097(3), β=93.28(4), V=429.4(2) Å³, Z=4; and Cu₂MgO(B₂O₅): a=3.2401(6), b=14.790(2), c=9.147(2), β=94.88(2), V=436.7(2) Å³, Z=4. The structures of Cu₂NiO(B₂O₅) and Cu₂MgO(B₂O₅) were, respectively, refined from 804 and 1000 independent reflections to the final residuals R1=0.0366, wR2=0.0911 and R1=0.0231, wR2=0.0644. Both compounds exhibit a chevron-like structure built up of ribbons, made of edge-connected copper and nickel-oxygen polyhedra, running along the (1 0 0) direction. These ribbons are connected from one another via oxygen atoms and the cohesion of the three-dimensional network is ensured by [B₂O₅] entities. Cu in part occupies the position for Ni or Mg, so that the compounds actually are solid solution compounds. Ni or Mg atoms are octahedrally coordinated by oxygen, while the two pure Cu sites show [4] and [4+1] coordination, for Cu(1) and Cu(2), respectively. The ELNES B-K edge spectra for the two compounds support that the borate group present is [B₂O₅].     

Novel solution phase metathetic pathway for the synthesis of MnV2O6·H2O

A novel solution-based approach for the metathetic synthesis of hydrated MnV₂O₆ driven by microwave energy has been successfully demonstrated. The metathetic pathway of synthesizing this technologically important material is confirmed by the presence of high lattice energy by-product NaCl as per the reaction.

     

Lamellar Fe/Al2O3 catalyst for high-yield production of multi-walled carbon nanotubes bundles

The lamellar Fe/Al₂O₃ catalysts were prepared by sol-gel method, and then with these prepared catalysts, carbon nanotubes (CNTs) were synthesized by catalytic chemical vapor deposition (CCVD) method using C₂H₂ as precursor. The as-prepared CNTs and Fe/Al₂O₃ catalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectrum. The results proved that the as-prepared CNTs actually existed in bundles. And the growth of CNTs bundles should be attributed to the lamellar catalysts, which supported the bottom growth mechanism of CNTs. The transition metal of Mo was not introduced in catalysts to produce CNTs bundles, which was different with others’ results.     

Synthesis and crystal structure of Sr10Al6O19: a derivative of the perovskite structure type in the system SrO-Al2O3

Sr₁₀Al₆O₁₉ is monoclinic, space group C12/c1, a=34.5823(21) Å, b=7.8460(6) Å, c=15.7485(9) Å, β=103.68(1)°, V=4151.9(7) Å³, Z=8. The structure has been solved from a single crystal diffraction dataset by direct methods and subsequently refined by a full-matrix least-squares process to a residual index of R(|F|)=0.038 for 2537 observed reflections with I>2σ(I). The compound is an oligoaluminate containing highly puckered [Al₆O₁₉]-groups of corner-sharing tetrahedra; it is the first purely aluminate cluster of this type, but it resembles the [□₆O₁₉]-group recently found in α-Sr₁₀□₆O₁₉. Linkage between the hexamers is provided by 11 crystallographically different strontium atoms located in planes parallel (1 0 0). They are coordinated by six-eight next oxygen neighbours. The structure can be derived from perovskite, ABO₃, by introducing ordered vacancies into the substructure of the oxygen atoms. The A-sites in Sr₁₀Al₆O₁₉ are exclusively occupied by Sr atoms, whereas strontium and aluminum atoms reside on the B-positions in the ratio 1:3. The relationship with perovskite can be expressed in the crystal chemical formula Sr(Al_3/4Sr_1/4)(O_19/8□_5/8).     

Synthesis, structure refinement and characterization of tetrahydrated acid gadolinium diphosphate HGdP2O7·4H2O

Synthesis and single crystal structure are reported for a new gadolinium acid diphosphate tetrahydrate HGdP₂O₇·4H₂O. This salt crystallizes in the monoclinic system, space group P2₁/n, with the following unit-cell parameters: a = 6.6137(2) Å, b = 11.4954(4) Å, c = 11.377(4) Å, β = 87.53(2)° and Z = 4. Its crystal structure was refined to R = 0.0333 using 1783 reflections. The corresponding atomic arrangement can be described as an alternation of corrugated layers of monohydrogendiphosphate groups and GdO₈ polyhedra parallel to the () plane. The cohesion between the different diphosphoric groups is provided by strong hydrogen bonding involving the W4 water molecule.

IR and Raman spectra of HGdP₂O₇·4H₂O confirm the existence of the characteristic bands of diphosphate group in 980–700 cm⁻¹ area. The IR spectrum reveals also the characteristic bands of water molecules vibration (3600–3230 cm⁻¹) and acidic hydrogen ones (2340 cm⁻¹). TG and DTA investigations show that the dehydration of this salt occurs between 79 and 900 °C. It decomposes after dehydration into an amorphous phase. Gadolinium diphosphate Gd₄(P₂O₇)₃ was obtained by heating HGdP₂O₇·4H₂O in a static air furnace at 850 °C for 48 h.     

Size and morphology-controlled Ni2[Fe(CN)6]·xH2O Prussian Blue analogue fabricated via a hydrothermal route

Nanocrystalline Prussian Blue analogue Ni₂[Fe(CN)₆]·xH₂O was synthesized through hydrothermal process at 180 °C for 24 h with NiSO₄·6H₂O and K₄[Fe(CN)₆]·3H₂O as precursors. The effects of reactant concentration and protective matrix (Polyethylene glycol 400, PEG-400) on the size and morphology of nanoparticles were investigated. The as-synthesized products were identified as face-centered cubic structure by powder X-ray diffraction. Field-emission scanning electron microscopy and transmission electron microscopy images showed that well dispersed nanoparticles with fairly narrow size distribution were successfully prepared.     

Structure refinement, infrared and Raman spectra of KDyP4O12

Crystals of KDyP₄O₁₂ have been grown by the flux technique and characterized by single-crystal X-ray diffraction. KDyP₄O₁₂ crystallizes in the monoclinic C2/c space group with lattice parameters: a=7.8158(3), b=12.3401(5), c=10.4382(3) Å, β=111.053°(2), V=939.6(4) Å³, Z=4. The crystal structure has been refined yielding a final R(F²)=0.034 and R_w(F²)=0.082 for 902 independent reflections (F_o²≥2σ(F_o²)). The structure of KDyP₄O₁₂ consists of DyO₈ polyhedra and cyclotetraphosphate P₄O₁₂ groups sharing oxygen atoms to form a three-dimensional framework, delimiting intersecting tunnels in which the potassium ion is located. Each K⁺ ion is bonded to 10 oxygen atoms. The energies of the vibrational modes of the crystal were obtained from measurements of the infrared and Raman spectra.     

Structural properties of Al2O3-La2O3 binary oxides prepared by sol-gel

The structural properties of La₂O₃ and Al₂O₃-La₂O₃ binary oxides prepared by sol-gel were studied by XRD, HRTEM and UV-vis. The binary oxides with high lanthana contents show an amorphous structure after calcination at 650 °C. At calcination temperatures higher than 1000 °C there is a phase transformation from the amorphous state to the crystalline LaAlO₃ with a perovskite structure. The structure of La₂O₃ is consistent with the hexagonal system; however, some crystalline microdomains with a monoclinic structure were detected by HRTEM. Islands of La₂O₃ and LaAl₁₁O₁₈ phases were detected at high lanthana concentration in the binary oxide. The modification in the coordination shell of the Al³⁺ cations due to the interaction with La³⁺ cations confirms the formation of phases with a perovskite structure and the presence of islands of the LaAl₁₁O₁₈ phase.     

Soft chemistry synthesis and crystal structure of MgxCu3−xV2O6(OH)4·2H2O

Mg_xCu_3−xV₂O₆(OH)₄·2H₂O (x ∼ 1), with similar crystal structure as volborthite Cu₃V₂O₇(OH)₂·2H₂O, was successfully prepared by a soft chemistry technique. The method consists of mixing magnesium nitrate and copper nitrate with a boiling solution of vanadium oxide (obtained by reacting V₂O₅ with few mL of 30 vol.% H₂O₂ followed by addition of distilled water). When ammonium hydroxide NH₄OH 10% was added (pH 7.8), a green yellowish precipitate was obtained. Using X-ray powder diffraction data, its crystal structure has been determined by Rietveld refinement. Compared to volborthite, the vanadium coordination changes from tetrahedral VO₄ to trigonal bipyramidal VO₅, and magnesium replaces copper, preferably, in the less distorted octahedron. At 300 °C, the phase formed is similar to the high pressure (HP) monoclinic Cu₃V₂O₈ phase. However at higher temperature, 600 °C, the phase obtained is different from known Cu₃V₂O₈ phases.     

Electrophoretic technique for hydrothermal synthesis of NaA zeolite membranes on porous α-Al2O3 supports

Uniform and dense NaA zeolite membranes were prepared on the α-Al₂O₃ support by electrophoretic technique. The membrane morphology and membrane thickness were investigated by XRD, SEM and pervaporation properties for dehydration of 95 wt.% isopropanol/water mixture at 343 K, respectively. Under the action of the applied electric field, the negatively charged zeolite particles could migrate to the support surface homogenously and rapidly, forming uniform and dense membranes in a short time. High quality NaA zeolite membrane, with a separation factor (water/isopropanol) of 3281 and a flux of 1.24 kg/m² h, could be prepared by electrophoretic technique with the electrical potential of 1 V. The formation mechanism of zeolite membrane in the electric field is discussed.