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1.
Orthorhombic Fe5(PO4)4(OH)3·2H2O single crystalline dendritic nanostructures have been synthesized by a facile and reproducible hydrothermal method without the aid of any surfactants. The influences of synthetic parameters, such as reaction time, temperature, the amount of H2O2 solution, pH values, and types of iron precursors, on the crystal structures and morphologies of the resulting products have been investigated. The formation process of Fe5(PO4)4(OH)3·2H2O dendritic nanostructures is time dependent: amorphous FePO4·nH2O nanoparticles are formed firstly, and then Fe5(PO4)4(OH)3·2H2O dendrites are assembled via a crystallization-orientation attachment process, accompanying a color change from yellow to green. The shapes and sizes of Fe5(PO4)4(OH)3·2H2O products can be controlled by adjusting the amount of H2O2 solution, pH values, and types of iron precursors in the reaction system. 相似文献
2.
Crystals of congruently melting K2Cd2(SO4)3 (having the langbeinite structure with a ferroelastic transition temperature of 156°C) were grown by the Bridgman and Czochralski techniques. The former yielded colorless crystals when using oxygen under pressure; the latter yielded tan crystals of slightly smaller unit cell volume and are assumed to be oxygen deficient. The ferroelastic transition was studied by thermal expansion measurements. Reexamination of the phase diagram showed the existence of a previously unreported phase K6Cd(SO4)4 which is stable only between 520°C and the melting point of about 890°C. 相似文献
3.
I. V. Medrish E. V. Peresypkina A. V. Virovets L. B. Serezhkina 《Crystallography Reports》2008,53(3):462-465
Three heteroacidoligand uranyl complexes M
4[(UO2)2C2O4(SO4)2(NCS)2] (M = K+ (I), Rb+ (II)) and K4[(UO2)2C2O4(SeO4)2(NCS)2] (III) have been synthesized and their crystal structure has been determined by X-ray diffraction analysis. The compounds I–III are isostructural and crystallized in the monoclinic system, sp. gr. P21/c, Z = 2, a = 11.5548(3) ?, b = 7.0847(1) ?, c = 13.5172(3) ?, β = 93.130(1)°, V = 1104.90(4), R = 0.015 (I); a = 11.5854(9) ?, b = 7.3841(6) ?, c = 13.9072(9) ?, β = 95.754(3)°, V = 1183.74(15), R = 0.0235 (II); a = 11.6715(3) ?, b = 7.1418(2) ?, c = 13.8546(1) ?, β = 93.539(1)°, V = 1152.66(5), R = 0.0126 (III). Basic structural units of these crystals are [(UO2)2C2O4(XO4)2(NCS)2]4− chains, which belong to the crystallochemical group A
2
K
02
B
22
M
21 (A = UO22+, K
02 = C2O2−4, B
2 = SO42− or SeO42−, M
1 = NCS−) of uranyl complexes. Uranium-containing chains are connected into a 3D framework via a system of electrostatic interactions
with potassium or rubidium cations from outer spheres.
Original Russian Text ? I.V. Medrish, E.V. Peresypkina, A.V. Virovets, L.B. Serezhkina, 2008, published in Kristallografiya,
2008, Vol. 53, No. 3, pp. 495–498. 相似文献
4.
L. B. Serezhkina A. V. Vologzhanina V. V. Klepov V. N. Serezhkin 《Crystallography Reports》2011,56(1):132-135
Single crystals of PbUO2(CH3COO)4(H2O)3 have been investigated by X-ray diffraction (R = 0.029 for 3175 reflections). The structure of this compound is formed by [Pb(CH3COO)(H2O)3]+ chains, which are oriented along the [100] axis and limited by one-core complexes [UO2(CH3COO)3]−. The coordination numbers of the Pb(II) and U(VI) atoms are 8, and the coordination polyhedron of uranium is a hexagonal bipyramid whose vertices contain oxygen atoms of
three bidentate cyclic acetate groups and the uranyl group. Taking into account the different crystallographic roles of acetate
ions, the crystal-chemical formula of [PbUO2(CH3COO)4(H2O)3] chains can be written as AA′B
21
B
11(B
01)2
M
31, where A = Pb; A′ = UO22+; M
1 = H2O; and B
21, B
11, and B
01 are CH3COO− groups. 相似文献
5.
L. B. Serezhkina E. V. Peresypkina A. V. Virovets M. O. Karasev 《Crystallography Reports》2010,55(1):19-23
Single crystals of the compound (NH4)3[UO2(CH3COO)3]2[UO2(CH3COO)(NCS)2(H2O)] (I) are synthesized, and their structure is investigated using X-ray diffraction. Compound I crystallizes in the monoclinic system with the unit cell parameters a = 18.3414(6) ?, b = 16.3858(7) ?, c = 12.4183(5) ?, β = 92.992(1)°, space group C2/c, Z = 4, V = 3727.1(3) ?3, and R = 0.0253. The uranium-containing structural units of crystals I are mononuclear complexes of two types with an island structure, i.e., the [UO2(CH3COO)3]− anionic complexes belonging to the crystal-chemical group (AB
301 = UO22+, B
01 = CH3COO−) of the uranyl complexes and the [UO2(CH3COO)(NCS)2(H2O)]− anionic complexes belonging to the crystal-chemical group AB
01M31 (A = UO22+, B
01 = CH3COO−, M
1 = NCS− or H2O). 相似文献
6.
L. F. Kirpichnikova M. Polomska A. Pietraszko V. S. Shakhmatov B. Hilczer 《Crystallography Reports》2005,50(1):108-114
X-ray diffraction measurements of mixed [(NH4)1−x
Rbx]3H(SO4)2 crystals of different compositions are performed. The characteristics of the change of the domain structure in the vicinity
of the supeprotonic-ferroelastic phase transition in crystals of different compositions are studied and compared with the
variations of the crystal structure in the course of gradual substitution of ammonium by rubidium. This phase transition is
theoretically described based on the phenomenological theory of a high-temperature phase transition.
__________
Translated from Kristallografiya, Vol. 50, No. 1, 2005, pp. 115–121.
Original Russian Text Copyright ? 2005 by Kirpichnikova, Polomska, Pietraszko, Shakhmatov, Hilczer. 相似文献
7.
L. F. Kirpichnikova A. Pietraszko W. Bednarski S. Waplak A. U. Sheleg 《Crystallography Reports》2004,49(1):86-93
Crystals grown from a solution of dimethylammonium and copper chlorides are studied using electron paramagnetic resonance
(EPR) and X-ray diffraction. The dielectric properties of the crystals grown are measured. It is established that the crystals
have the composition [(CH3)2NH2]2CuCl4[(CH3)2NH2]Cl and, in phase I at room temperature, are described by the orthorhombic space group Pna21 with the unit cell parameters a = 11.338 Å, b = 9.981 Å, and c = 15.675 Å. At temperatures of 279 K and 253 K, the crystals undergo jumpwise phase transitions into the incommensurate modulated
ferroelectric phase II and commensurate modulated phase III, respectively.
__________
Translated from Kristallografiya, Vol. 49, No. 1, 2004, pp. 92–100.
Original Russian Text Copyright ? 2004 by Kirpichnikova, Pietraszko, Bednarski, Waplak, Sheleg.
Dedicated to the 80th Birthday of L.A. Shuvalov 相似文献
8.
Single crystals of rare earth (RE) selenates of the compositions Nd(HSeO4)3, Sm(HSeO4)3, and Nd2(SeO4)3 · 5H2O are synthesized and studied by X-ray diffraction analysis at T = 297 and 180 K. It is established that Nd and Sm hydrogen selenates are isostructural to one another and to the corresponding
hydrogen sulfates. Neodymium selenate pentahydrate is not isostructural to the analogous RE sulfates, although their structural
motifs are similar.
__________
Translated from Kristallografiya, Vol. 49, No. 5, 2004, pp. 835–840.
Original Russian Text Copyright ? 2004 by Zakharov, Troyanov, Kemnitz. 相似文献
9.
I. V. Karpa S. A. Sveleba I. M. Kunyo I. M. Katerynchuk O. V. Semotyuk O. I. Blashko 《Crystallography Reports》2010,55(5):815-820
The time dependences of the birefringence and thermal conductivity of [N(CH3)4]2CuCl4 and [N(CH3)4]2Zn0.98Ni0.02Cl4 crystals in the incommensurate phase at a constant temperature have been studied. A multiwave state of modulated superstructure
is found to be formed in the presence of defect density waves in the crystal. It is shown that, depending on the number of
defect density waves in the crystal, either a superposition of existing modulation waves or a domainlike structure arise in
it. 相似文献
10.
The crystal structure of a new synthetic aluminophosphate {[Rb1.94(H2O,OH)3.84](H2O)0.1}{Al4(OH)4[PO4]3} synthesized under mild hydrothermal conditions (T = 280°C, P = 100 atm) in the Rb2O-Al2O3-P2O5-H2O system is determined using X-ray diffraction (Stoe IPDS diffractometer, λMoK
α, graphite monochromator, 2θmax = 64.33°, R = 0.032 for 312 reflections). The main crystal data are as follows: a = 7.4931(6) ?, space group P
3m, Z = 1, and ρcalcd = 2.76 g/cm3. It is shown that the synthesized compound belongs to the pharmacosiderite structure type with a characteristic mixed open
microporous framework composed of octahedra and tetrahedra. A comparative crystal chemical analysis of related phases is performed,
and the chemical compositions of promising absorbents, i.e., hypothetical compounds potentially possible in the structure
type under consideration, are proposed. It is established that pharmacosiderite and rhodizite are homeotypic to each other.
Original Russian Text ? O.V. Yakubovich, W. Massa, O.V. Dimitrova, 2008, published in Kristallografiya, 2008, Vol. 53, No.
3, pp. 442–449. 相似文献
11.
Walid Rekik Houcine Na?li Tahar Mhiri Thierry Bataille 《Journal of chemical crystallography》2007,37(2):147-155
The crystal structure of manganese sulfate templated by 1,4-diaza-bicyclo[2.2.2]octane (abbreviated dabco), (C6H14N2)[Mn(H2O)6](SO4)2, was investigated using single crystal X-ray diffraction data. It crystallises in the monoclinic system (space group P21/c) with the following unit-cell parameters: a = 12.1392(2) ?, b = 12.3117(2) ?, c = 12.2765(2) ?, β = 104.607(1)°, V = 1775.47(5) ?3 and Z = 4. The structure has been solved using direct methods and refined by least-squares analysis [R
1 = 0.0381, wR
2 = 0.1082]. The crystal structure of the title compound is built from isolated [Mn(H2O)6]2+ octahedral cations, 1,4-diaza-bicyclo[2.2.2]octandiium cations (C6H14N2)2+ and sulfate anions (SO4)2− connected by a three-dimensional hydrogen-bond network. The thermal decomposition of the precursor, studied by thermogravimetry
and temperature-dependent X-ray powder diffraction, proceeds through four stages giving rise to the mixture of Mn2O3and Mn3O4.
Supplementary Material CCDC 620298 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. 相似文献
12.
E. V. Alekseev E. V. Sulemanov E. V. Chuprunov G. K. Fukin E. V. Baranov 《Crystallography Reports》2007,52(2):266-270
Single crystals of bis(dimethyl sulfoxide) uranyl sulfate are prepared, and their crystal structure is determined using X-ray
diffraction analysis. The crystals are monoclinic, space group P21/c, a = 12.9189(8) ?, b = 7.9008(5) ?, c = 12.1405(7) ?, β = 95.677(1)°, R
1 = 0.0216, wR
2 = 0.0468 for 2761 unique reflections with F > 2σ(F). The crystal structure of the UO2SO4 · 2Dmso compound (where Dmso is dimethyl sulfoxide) is built up of infinite uncharged ribbons of the composition [UO2SO4 · 2Dmso]∞, in which the SO4 tetrahedron is tridentately coordinated to two uranyl groups. The differences between the structures of the uranyl sulfate
compounds formed upon replacement of dimethyl sulfoxide by other molecules are considered.
Original Russian Text ? E.V. Alekseev, E.V. Suleĭmanov, E.V. Chuprunov, G.K. Fukin, E.V. Baranov, 2007, published in Kristallografiya,
2007, Vol. 52, No. 2, pp. 283–286. 相似文献
13.
14.
Daniel L. Reger Mark D. Smith Kenneth J. Brown 《Journal of chemical crystallography》2009,39(8):545-548
Abstract The cation in the solid state structure of [Fe{HC(3,5-Me2pz)3}2][Fe2OCl6] (pz = pyrazolyl ring) contains an octahedral iron(II) center with an average Fe–N bond distance of 2.17 Å, indicating that
the iron(II) is in the high-spin form. While M–N bond distances of this length with κ3-[HC(3,5-Me2pz)3] ligands generally cause tilting of pz to open up the “bite” angle, in this structure the average tilting angle is only 3.1°,
a much lower value than observed in earlier structures of this same cation paired with different anions. The crystals are
monoclinic, space group P21/n, with a = 11.1671(12) Å, b = 10.8091(11) Å, c = 17.4385(17) Å, α = γ = 90°, β = 95.685(2)°, and Z = 2.
Graphical Abstract The cation in the solid state structure of [Fe{HC(3,5-Me2pz)3}2][Fe2OCl6] (pz = pyrazolyl ring) contains an octahedral iron(II) center in the high-spin form with unusual orientations of the pyrazolyl
rings.
相似文献
15.
Gel-glass transformation has been studied by Mössbauer spectroscopy, DTA-TG analyses and X-ray diffractometry for four compositions in the SiO2Fe2O3 system (A: 5 wt% Fe2O3, B: 10 wt% Fe2O3, C: 20 wt% Fe2O3, D: 40 wt% Fe2O3).The gels were prepared by the hydrolysis of silicon tetraethoxide and iron triethoxide and successively dried and heated in oxygen in the temperature range 40–1000°C.Samples A and B gave typical amorphous X-ray patterns up to 700°C; heating at higher temperature yielded the precipitation of quartz, cristobalite and hematite in sample A, cristobalite and hematite in sample B. Crystallization was also detected by DTA in sample A for which X-ray diffraction exhibited a larger effect.In samples C and D crystallization took place starting from 300°C with the precipitation of hematite, which remained the only crystalline phase up to 1000°C.The presence of hematite was confirmed by the obtained Mössbauer spectra which showed the characteristic sextet. The apportion of iron ions in the Fe3+ and Fe2+ oxidation states was also determined, together with the attribution of the probable coordination states for Fe3+ ions.Complex magnetic structure appeared in samples treated above 800°C. 相似文献
16.
The results of magnetic measurements performed on 20Fe2O380[3B2O3(1?χ)PbOχAs2O3] glasses, in the temperature range 4.2 to 300 K are reported. By decreasing the temperature a downward curvature of reciprocal susceptibility is observed for T<50 K. The composition dependence of the paramagnetic Curie temperatures and Curie constants is discussed. 相似文献
17.
Monolithic silica glass was obtained by heating the gels prepared by hydrolyzing Si(OC2H5)4 with NH4OH and HCl solution. The effect of the condition of hydrolysis of Si(OC2H5)4 on glass formation was examined by measuring the bulk density, the infrared spectra and the thermal shrinkage of the gel on heating. The gel prepared by hydrolysis with NH4OH solution consisted of numerous spherical particles, the bulk density being about 0.8. This gel abruptly shrank at about 1050°C, being converted to the pore free material similar to fused silica. The conversion of the gel to glass followed the sintering model in which the viscous flow controlled the sintering process. The viscosity and the activation energy for viscous flow were calculated on the basis of the Frenkel equation. On the other hand, the spherical particles were not observed in the gel prepared by hydrolysis with HCl solution. The bulk density of the gel was about 1.8. This gel was converted to glass at about 700°C, which was lower than the temperature of glass formation for the gel obtained by hydrolysis with NH4OH solution. 相似文献
18.
NdAl3(BO3)4 single crystals were grown by the flux method and the TSSG technique using a K2O/3MoO3/B2O3/0.5Nd2O3/KF flux system. Light-violet clear crystals could be obtained. The effects of fluoride on the growth of NAB crystals were investigated. As the content of KF was gradually increased, the growth form of NAB was changed from the equant to the columnar and the primary crystalline region of NAB was shrinked. At the ratio of KF/K2O = 0.75, NAB crystals could not be grown. 相似文献
19.
Two phase transitions are revealed for the first time in Ag3Sc2(PO4)3 single crystals in the vicinity of the temperatures 303 and 165–180 K. It is established that the phase transition at 303
K corresponds to the well-known phase transition to the superionic state in Na3Sc2(PO4)3 single crystals in the temperature range 423–433 K, whereas the phase transition observed in the temperature range 170–180
K corresponds to the phase transition from the rhombohedral to monoclinic phase at about 320 K in the monoclinic Na3Sc2(PO4)3 single crystals. It is also established that rhombohedral Na3Sc2(PO4)3 single crystals undergo the second phase transition.
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Translated from Kristallografiya, Vol. 50, No. 1, 2005, pp. 122–126.
Original Russian Text Copyright ? 2005 by Shilov, Atovmyan, Kovalenko. 相似文献
20.
L. V. Soboleva 《Crystallography Reports》2007,52(6):1104-1107
On the basis of the physicochemical analysis of the solubility phase diagrams for the Me
2SO4-NiSO4-H2O ternary systems (Me = Na, Rb, or Cs), the optimum concentration and temperature conditions for the crystallization of the Me
2Ni(SO4)2 · nH2O solid phases were found. Techniques for growth of single crystals of these binary salts have been developed. Such techniques
allow application of mother liquors containing hydrates or anhydrous sulfates of Na, Rb, Cs, and Ni as raw materials. Na2Ni(SO4)2 · 4H2O, Rb2Ni(SO4)2 · 6H2O, and Cs2Ni(SO4)2 · 6H2O single crystals (28–34) × (8–13) × (5–10) mm3 in size have been grown from aqueous solutions in the dynamic regime.
Original Russian Text ? L.V. Soboleva, 2007, published in Kristallografiya, 2007, Vol. 52, No. 6, pp. 1141–1144. 相似文献