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1.
The phase relations in the cross-section of the K2W2O7-K2WO4-KPO3 containing 15 mol% Bi2O3 were undertaken using flux method. Crystallization fields of K6.5Bi2.5W4P6O34, K2Bi(PO4)(WO4), Bi2WO6, KBi(WO4)2 and their cocrystallization areas were identified. Novel phase K6.5Bi2.5W4P6O34 was characterized by single-crystal X-ray diffraction: sp. gr. P−1, a=9.4170(5), b=9.7166(4), c=17.6050(7) Å, α=90.052(5)°, β=103.880(5)° and γ=90.125(5)°. It has a layered structure, which contains {K7Bi5W8P12O68} layers stacked parallel to ab plane and sheets composed by potassium atoms separating these layers. Sandwich-like {K7Bi5W8P12O68} layers are assembled from [W2P2O13] and [BiPO4] building units, and are penetrated by tunnels with K/Bi atoms inside. FTIR-spectra of K2Bi(PO4)(WO4) and K6.5Bi2.5W4P6O34 were discussed on the basis of factor group theory.  相似文献   

2.
K3InF6 is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K3InF6 by decomposition at high temperature. The crystal structure of K3InC12O14H4F18 is characterized by complex anions [In(CF3COO)4(OHx)2](5−2x)− and isolated [CF3COOH2−x](x−1)− molecules with x=2 or 1, surrounded by K+ cations. The crystal structure of K3InC12O12F18 is only constituted by complex anions [In(CF3COO)6]3− and K+ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K2InC10O10H6F9 and K3InC12O12F18 were also performed at room temperature on pulverized crystals.  相似文献   

3.
phase diagrams of KCl-KBO2-K2CO3, K2MoO4-KBO2-K2CO3, and K2WO4-KBO2-K2CO3 ternary systems were studied by a calculation-experimental method and differential thermal analysis (DTA). The coordinates of ternary eutectics were determined to be E 1: 622°C, 8.5 mol % KBO2, 56.5 mol % KCl, and 35 mol % K2CO3; E 2: 710°C, 23 mol % KBO2, 43 mol % K2CO3, and 34 mol % K2MoO4; E 3: 710°C, 23 mol % KBO2, 43 mol % K2CO3, and 34 mol % K2WO4. The specific heats of melting of the eutectics were determined.  相似文献   

4.
The phase diagrams of the NaBO2-NaCl-Na2CO3, NaBO2-Na2CO3-Na2MoO4, NaBO2- Na2CO3-Na2WO4, and NaBO2-NaCl-Na2WO4 ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary eutectics were determined: E 1: 612°C, 16 mol % NaBO2, 42 mol % NaCl, and 42 mol % Na2CO3; E 2: 568°C, 12 mol % NaBO2, 28 mol % Na2CO3, and 60 mol % Na2MoO4; E 3: 575°C, 12 mol % NaBO2, 32 mol % Na2CO3, and 56 mol % Na2WO4; E 4: 628°C, 8 mol % NaBO2, 20 mol % NaCl, and 72 mol % Na2WO4; and E 5: 655°C, 9 mol % NaBO2, 53 mol % NaCl, and 38 mol % Na2WO4.  相似文献   

5.
The structural, electronic, and vibrational characteristics and energies of the isolated polyoxide clusters B20O30, Al20O30, V20O50, Si20O30H20, and Si20O30F20 and their complexes with the H ion and ammonia complexes Al20O30 · nNH3 have been calculated by the density functional theory B3LYP method with different basis sets. The computation results show that the symmetric closo structure I h with oxygen bridges located above the centers of the faces of an empty [M20] dodecahedron is more favorable for V20O50, Si20O30H20, and Si20O30F20. For B20O30, the cage closo isomer is also more favorable than the other isomers, but its structure is severely distorted as compared to a dodecahedron and has a symmetry close to C 3 . For Al20O30, the I h structure corresponds to a high-lying local minimum of the potential energy surface. For Al20O30, a set of unusual puckshaped isomers of symmetry C i , with different numbers of four-coordinate atoms IVAl and three-coordinate atoms IIIO, was localized; these structures are more than 90 kcal/mol more favorable than the dodecahedron I h . The most favorable isomer of Al20O30 contains twelve four-coordinate atoms IVAl and four five-coordinate atoms VAl. The energies of dissociation of the most favorable M20O30 clusters into the M2O3 (C 2v ) and M4O6 (T d ) fragments and, in the case of Al20O30, also into the Al8O12 (O h ) and Al12O18 (D 3d ) fragments, have been estimated. The conclusion has been drawn that these clusters can, in principle, exist and can be experimentally detected in the isolated state. Analogous calculations have been performed for ammonia complexes Al20O30 · nNH3 with n varying from 1 to 20. The effect of solvation on the relative stability of the dodecahedral and puckshaped isomers of the Al20O30 cluster is observed. The isomers with ammonia molecules in their first coordination sphere become much closer to one another on the energy scale; however, the dodecahedron remains a considerably less favorable intermediate. Original Russian Text ? O.P. Charkin, N.M. Klimenko, D.O. Charkin, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 4, pp. 624–635.  相似文献   

6.
The following complex oxynitride perovskites have been prepared: LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9. Synchrotron X-ray powder diffraction analyses show that LaMg1/3Ta2/3O2N and LaMg1/2Ta1/2O5/2N1/2 are isostructural to the oxide La2Mg(Mg1/3Ta2/3)O6 (space group P21/n), whereas BaSc0.05Ta0.95O2.1N0.9 has a simple cubic symmetry similarly to BaTaO2N. The orderings of octahedral cations are markedly diminished in the above oxynitrides, as compared with the related oxides such as La2Mg(Mg1/3Ta2/3)O6 and Ba2ScTaO6. The optical band gaps are similar for the homologous compositions, LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2 and LaTaON2 (1.9 eV), and BaSc0.05Ta0.95O2.1N0.9 and BaTaO2N (1.8 eV), while the absorption edges become broader for the complex derivatives. As revealed from the impedance spectroscopic analysis, the oxynitrides have clearly different dielectric components from those of comparable oxides containing Ta5+. Impedance spectroscopy reveals interesting capacitor geometry in BaSc0.05Ta0.95O2.1N0.9 in which the semiconducting oxynitride grains are separated by insulating secondary phases. Most notably BaSc0.05Ta0.95O2.1N0.9 has a bulk component with a high relative permittivity (κ=7300) and the grain boundary component with an even higher κ.  相似文献   

7.
This paper examines the structural changes with temperature and composition in the Sc2Si2O7-Y2Si2O7 system; members of this system are expected to form in the intergranular region of Si3N4 and SiC structural ceramics when sintered with the aid of Y2O3 and Sc2O3 mixtures. A set of different compositions have been synthesized using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1750 °C during different times. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β-RE2Si2O7 polymorph, with γ-RE2Si2O7 and δ-RE2Si2O7 showing very reduced stability fields. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of the components. Although, the XRD data show a complete solid solubility of β-Sc2Si2O7 in β-Y2Si2O7 at 1300 °C, the 29Si MAS-NMR spectra indicate a local structural change at x ca. 1.15 (Sc2−xYxSi2O7) related to the configuration of the Si tetrahedron, which does not affect the long-range order of the β-RE2Si2O7 structure. Finally, it is interesting to note that, although Sc2Si2O7 shows a unique stable polymorph (β), Sc3+ is able to replace Y3+ in γ-Y2Si2O7 in the compositional range 1.86?x?2 (where x is Sc2−xYxSi2O7) as well as in δ-Y2Si2O7 for compositions much closer to the pure Y2Si2O7.  相似文献   

8.
Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.  相似文献   

9.
The Tl2S-Sb2S3-Bi2S3 quasi-ternary system (system A) was studied using DTA, X- ray powder diffraction, microstructure examination, and microhardness measurements. TlSbS2-Tl4Bi2S5(TlBiS2, Bi2S3), Sb2S3-TlBiS2, Tl3SbS3-TlBiS2(Bi2S3), and [TlSb0.5Bi0.5S2]-Tl2S isopleths; isothermal sections at 500 K; and liquidus surface projection of system A were constructed. Characteristic features of the title system are extensive fields of solid solutions extended along the TlSbS2-TlBiS2 quasi-binary section and a continuous solubility belt 1–2 mol % wide extended along the Sb2S3-Bi2S3 binary subsystem. Primary separation fields of phases and the types and coordinates of invariant and monovariant equilibria in system A were determined.  相似文献   

10.
Four definite compounds exist in the Sm2O3Ga2O3 binary phase diagram, namely: Sm3GaO6, Sm4Ga2O9, SmGaO3, and Sm3Ga5O12. The 31 compound is orthorhombic (space group Pnna - Z.4) with the cell parameters: a = 11.400Å, b = 5.515Å, c = 9.07Å and belongs to the oxysel family. Sm3GaO6 and SmGaO3 melt incongruently at 1715 and 1565°C; Sm4Ga2O9 and Sm3Ga5O12 have a congruent melting point at 1710 and 1655°C. With regard to the Gd2O3Ga2O3 system three definite compounds have been identified: Gd3GaO6, Gd4Ga2O9, and Gd3Ga5O12. Only the garnet melts congruently at 1740°C with the following composition: Gd3.12Ga4.88O12. Gd3GaO6, and Gd4Ga2O9 melt incongruently at 1760 and 1700°C. GdGaO3 is only obtained by melt overheating which may yield an equilibrium or a metastable phase diagram.  相似文献   

11.
New polar vanadium tellurite enantiomers have been synthesized under mild hydrothermal conditions through the use of sodium metavanadate, sodium tellurite and enantiomerically pure sources of either R-3-aminioquinuclidine or S-3-aminioquinuclidine. [R-C7H16N2][V2Te2O10] and [S-C7H16N2][V2Te2O10] contain [V2Te2O10]n2n layers constructed from [(VO2)2O(TeO4)2] monomers. Steric effects associated with the hydrogen-bonding network between the [V2Te2O10]n2n layers and [C7H16N2]2+ result in polar structures and crystallization in the space group P21 (no. 4). Electron localization functions were calculated to visualize the tellurite stereoactive lone pairs. Both iterative and non-iterative Hirshfeld techniques were evaluated as means to determine atomic partial charges, with iterative Hirshfeld charges more accurately representing charge distributions in the reported enantiomers. These charges were used to calculate both component and net dipole moments. [R-C7H16N2][V2Te2O10] and [S-C7H16N2][V2Te2O10] exhibit dipole moments of 17.37 and 16.62D, respectively. [R-C7H16N2][V2Te2O10] and [S-C7H16N2][V2Te2O10] both display type 1 phase-matching capabilities and exhibit second harmonic generation activities of ∼50×α-SiO2.  相似文献   

12.
一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…  相似文献   

13.

Abstract  

The intermetallic zinc compounds La3Pd4Zn4 and La3Pt4Zn4 were synthesized by induction melting of the elements in sealed tantalum tubes. The structures were refined from X-ray single-crystal diffractometer data: Gd3Cu4Ge4 type, Immm, a = 1,440.7(5), b = 743.6(2), c = 419.5(2) pm, wR 2 = 0.0511, 353 F 2 for La3Pd4Zn4; and a = 1,439.9(2), b = 748.1(1), c = 415.66(6) pm, wR 2 = 0.0558, 471 F 2 for La3Pt4Zn4 with 23 variables per refinement. The palladium (platinum) and zinc atoms build up a three-dimensional polyanionic [Pd4Zn4] (260–281 pm Pd–Zn) and [Pt4Zn4] (260–279 pm Pt–Zn) network in which the lanthanum atoms fill cavities of CN 14 (6 Pd/Pt + 8 Zn for La1) and CN 12 (6 Pd/Pt + 6 Zn for La2), respectively. The copper position of the Gd3Cu4Ge4 type is occupied by zinc and the two crystallographically independent germanium sites by palladium (platinum), a new coloring pattern for this structure type. Within the [Pd4Zn4] and [Pt4Zn4] the Pd2 and Pt2 atoms form Pd2–Pd2 (291 pm) and Pt2–Pt2 (296 pm) dumbbells. The structures of La3Pd4Zn4 and La3Pt4Zn4 are discussed with respect to the prototype Gd3Cu4Ge4 and the Zintl phase Sr3Li4Sb4. Temperature-dependent magnetic susceptibility measurements indicate diamagnetism for La3Pt4Zn4 and Pauli paramagnetism for La3Pd4Zn4.  相似文献   

14.
The magnetic ordering of the Fe2P-type Tb6FeTe2, Tb6CoTe2 Tb6NiTe2 and Er6FeTe2 phases (space group P6¯2m) has been investigated through magnetization measurement and neutron powder diffraction. Tb6FeTe2, Tb6CoTe2 and Tb6NiTe2 demonstrate high-temperature ferromagnetic and low-temperature spin reorientation transitions, whereas Er6FeTe2 shows antiferromagnetic transition, only.The Tb6FeTe2 and Tb6NiTe2 phases show same high-temperature collinear ferromagnetic structure, whereas Tb6FeTe2 is the commensurate non-collinear ferromagnet and Tb6NiTe2 is the canted ferromagnetic cone with K1=[0, 0, ±3/10] and K2=[±2/9, ±2/9, 0] wave vectors at 2 K. The magnetic structure of Er6FeTe2 is a flat spiral with K1=[0, 0, ±1/10] at 2 K. The magnetic entropy change for Tb6NiTe2 is ΔSm=−4.86 J/kg K at 229 K for the field change Δμ0H=0-5 T.In addition, novel Fe2P-type Gd6FeTe2, Zr6FeTe2, Hf6FeTe2, Dy6NiTe2, Zr6NiTe2 and Hf6NiTe2 phases have been obtained.  相似文献   

15.
Specific features of the thermal behavior of Bi m + 1Fe m−3Ti3O3m + 3 layered perovskite-like compounds (where m takes integer and some fractional values between 3 and 9) were considered, and the temperature limits of stability of these compounds were determined. The phase diagram of the Bi4Ti3O12-BiFeO3 section through the Bi2O3-TiO2-Fe2O3 system was constructed.  相似文献   

16.
Preparation of new solid solutions containing divalent europium have been tried in the systems Eu2Nb2O7Sr2Nb2O7 and Eu2Ta2O7Sr2Ta2O7. These solid solutions described as Eu2xSr2(1?x)M2O7 (M = Nb and Ta) exist in a pure orthorhombic phase in a limited region of x from 0 to about 0.5. The compounds with compositions close to Eu2M2O7 exist but techniques have not been found to prepare them in pure form.  相似文献   

17.
The novel, 1D semiconductor (H2NC4H8NCH2CH2NH2)(HNCH2CH2NH2)3Zn2Ge2Se8 has been synthesized under solvothermal conditions using N-(2-aminoethyl)piperazine as solvent and templating agent at 200 °C. The material was characterized by single crystal and powder X-ray diffraction, IR and Raman spectroscopy and thermogravimetric analysis. The compound consists of 1D anionic [Zn2Ge2Se8]4− chains made of alternating edge-shared [ZnSe4] and [GeSe4] tetrahedra that charged balanced by one N-(2-aminoethyl)piperazinium and three piperazinium cations. The optical properties were investigated with solid state UV–Vis/near IR spectroscopy and the results show that the solid is a medium gap semiconductor with an absorption edge at 1.8 eV.  相似文献   

18.
Preparation and crystal structure of the novel compound [Bi3I(C4H8O3H2)2(C4H8O3H)5]2Bi8I30 are reported. The title compound is prepared by heating of BiI3 and diethylene glycol at 413 K in a sealed quartz glass tube filled with argon. Deep red single crystals are grown and applied to perform X-ray powder diffraction and X-ray single-crystal diffraction measurements. The compound crystallizes triclinic with space group P-1: Z=2, a=13.217(1) Å, b=15.277(1) Å, c=22.498(1) Å, α=84.33(1), β=73.18(1), γ=67.48(1). [Bi3I(C4H8O3H2)2(C4H8O3H)5]2Bi8I30 comprises the novel polynuclear [Bi8I30]6− anion and [Bi3I(C4H8O3H2)2(C4H8O3H)5]3+ as the cation. Cation as well as the anion can be assumed to represent intermediates between solid BiI3 and BiI3 completely dissolved in diethylene glycol.  相似文献   

19.
The NaCdVO4-Cd3V2O8 and CdO-V2O5 sections of the ternary system Na2O-CdO-V2O5 have been studied and the crystal structures of Cd3V2O8 and Cd18V8O38 compounds were determined from single-crystal X-ray diffraction data. Cd3V2O8 crystallizes with the maricite-type structure in space group Pnma, a=9.8133(10) Å, b=6.9882(10) Å, c=5.3251(10) Å and Z=4, whereas Cd18V8O38 crystallizes in space group P1 with a new-type structure, a=8.5761(14), b=8.607(3), c=12.896(2) Å, α=95.64(1), β=102.45(1), γ=108.42(1)° and Z=1. The Cd3V2O8 structure is made up of Cd1O4 infinite chains of edge-sharing Cd1O6 octahedra which are parallel to the b direction. The Cd1O4 chains are linked together by VO4 tetrahedra and strongly distorted Cd2O4 tetrahedra. The structure of Cd18V8O38 is based on an ordered three-dimensional framework of cadmium and vanadium polyhedra that share corners. The distorted CdO6 octahedra, CdO5 trigonal bipyramids and CdO5 square pyramids share corners, edges or faces.  相似文献   

20.
A serial of samples in Y2O3-Ga2O3-Tm2O3 pseudo-ternary system are prepared by solid-state chemical reaction method. The range of solid solution in (Y1−xTmx)3GaO6 is 0<x<0.384. Powder X-ray diffraction shows that the compounds crystallize in Gd3GaO6 (Cmc21)-type structure. The solid solubilities of Y3+xGa5−xO12 (x=0-0.77) and Tm3+xGa5−xO12 (x=0-0.62) are 37.5-47.11 at% Y2O3, and 37.5-45.26 at% Tm2O3, respectively. PL spectra of Tm-doped Y3GaO6 show that there is a sharp blue emission at ∼456 nm from the 1D23F4 transition at room temperatures with two lifetimes (∼5 and ∼15 μs) and a narrow saturation range of PL intensity for the Tm3+ content from x=0.005 to 0.03. The sharp emission and long lifetime of (Y1−xTmx)3GaO6 indicate that Y3GaO6 is a potential phosphor and laser crystal host material.  相似文献   

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