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1.
NaZr2–xBx(PO4)3–2x(SO4)2x (0 ≤ x ≤ 1.25, B = Mg, Co, Ni, Cu, Zn), and NaZr2–xRx(PO4)3–x(SO4)x (0 ≤ x ≤ 1.25, R = Al, Fe) phosphate-sulfates series have been prepared by a sol–gel process. These compounds belong to the NaZr2(PO4)3 (NZP) structure family and crystallize in hexagonal crystal system, space group R\(\bar 3\)c. Limited solid solution series were found to exist; their formation temperatures and thermal stability limits were determined. Particle sizes as determined by microstructure observation were 50–200 nm, and for Cu- and Zn-containing samples, 200–500 nm. The thermal expansion of phosphate-sulfate NaZr1.25Cu0.75(PO4)1.5(SO4)1.5 was studied in the range 25–700°C. Thermal expansion coefficients and thermal expansion anisotropy were found to be αa =–5.40 × 10–6 °C–1, αс = 18.88 × 10–6 °C–1, αavg = 2.69 × 10–6 °C–1, and Δα = 24.28 × 10–6 °C–1.  相似文献   

2.
Isomorphic substitution of neodymium and gadolinium for calcium in synthetic hydroxovanadate Ca5 ? x M x (VO4)3(OH)1 ? x O x (M = Nd, Gd) is studied in the range 700–1000°C using X-ray powder diffraction, single-crystal X-ray diffraction (Rietveld technique), and IR spectroscopy. Single-phase solid solutions at 800°C are formed with x ≤ 0.35 for M(III) = Nd and x ≤ 0.3 for M(III) = Gd. With high x, the apatite solid solution coexists with Ca3(VO4)2, Nd2O3, and X phases. With increasing x in the homogeneous region, the intensity of the bands of stretching vibrations and librations of OH groups decrease. Single-crystal X-ray diffraction shows that neodymium and gadolinium substitute for calcium in solid solutions mostly in Ca(2) positions.  相似文献   

3.
Sodium zirconium arsenate phosphates NaZr2(AsO4) x (PO4)3?x were synthesized by precipitation technique and studied by X-ray diffraction and IR spectroscopy. In the series of NaZr2(AsO4) x (PO4)3?x , continuous substitution solid solutions are formed (0 ≤ x ≤ 3) with the mineral kosnarite structure. The crystal structure of NaZr2(AsO4)1.5(PO4)1.5 was refined by full-profile analysis: space group R \(\bar 3\) c, a = 8.9600(4)Å, c = 22.9770(9) Å, V = 1597.5(1) Å3, R wp = 4.55. The thermal expansion of the arsenate-phosphate NaZr2(AsO4)1.5(PO4)1.5 and the arsenate NaZr2(AsO4)3 was studied by thermal X-ray diffraction in the temperature range of 20–800°C. The average linear thermal expansion coefficients (αav = 2.45 × 10?6 and 3.91 × 10?6 K?1, respectively) indicate that these salts are medium expansion compounds.  相似文献   

4.
The phase diagrams of binary systems of gallium sulfate with lithium or sodium sulfate were studied for the first time. The Li2SO4–Ga2(SO4)3 system is of the eutectic type. The coordinates of the eutectic are (548°C, 30 mol % Ga2(SO4)3). The region of a solid solution based on the high-temperature modification α-Li2SO4 is small. In the Na2SO4–Ga2(SO4)3 system, compound Na3Ga(SO4)3 forms, which melts incongruently at 585°C. The coordinates of the eutectic are (538°C, 17 mol % Ga2(SO4)3). The region of a solid solution based on α-Na2SO4 reaches 8 ± 1 mol % Ga2(SO4)3. The X-ray powder diffraction pattern of Na3Ga(SO4)3 was indexed in a tetragonal unit cell with the parameters a = 9.451(3) Å and c = 7.097(3) Å; the unit cell parameters for an aluminum-containing analog, Na3Al(SO4)3, are a = 9.424(5) Å and c = 7.053(3) Å.  相似文献   

5.
A possibility of substitution of barium for strontium in Sr10(VO4)6(OH)2 is studied by X-ray powder diffraction and IR spectroscopy. According to X-ray powder diffraction data, single-phase solid solutions Sr10 ? x Ba x (VO4)6(OH)2 are formed with x = 0–2.5 with an increase in the unit cell parameters.  相似文献   

6.
It was shown that the monomeric rhodium sulfate complexes [Rh(H2O)4(SO4)]+, trans-[Rh(H2O)2(SO4)2]?, cis-[Rh(H2O)2(SO4)2]?, and [Rh(SO4)3]3? were not predominant forms in aqueous solutions. The 103Rh NMR chemical shifts of the complexes were assigned, and the conditions for their formation in solutions, concentration parameters, and acidity at which the fraction of the monomers was maximal were determined. The constants of formation of the complexes and ion pair (IP) were estimated: K IP = 8 ± 3.5, K 1 ≈ 8, K 2trans ≈ 1, K 2cis ≈ 1, and K 3 ≈ 2.  相似文献   

7.
A series of Cr-doped Li3V2???x Cr x (PO4)3 (x?=?0, 0.1, 0.25, and 0.5) samples are prepared by a sol–gel method. The effects of Cr doping on the physical and chemical characteristics of Li3V2(PO4)3 are investigated. Compared with the XRD pattern of the undoped sample, the XRD patterns of the Cr-doped samples have no extra reflections, which indicates that Cr enters the structure of Li3V2(PO4)3. As indicated by the charge–discharge measurements, the Cr-doped Li3V2???x Cr x (PO4)3 (x?=?0.1, 0.25, and 0.5) samples exhibit lower initial capacities than the undoped sample at the 0.2 C rate. However, both the discharge capacity and cycling performance at high rates (e.g., 1 and 2 C) are enhanced with proper amount of Cr doping (x?=?0.1). The highest discharge capacity and capacity retention at the rates of 1 and 2 C are obtained for Li3V1.9Cr0.1(PO4)3. The improvement of the electrochemical performance can be attributed to the higher crystal stability and smaller particle size induced by Cr doping.  相似文献   

8.
Phase relationships in the subsolidus region of the system Na2MoO4-MnMoO4-Cr2(MoO4)3 were studied by means of X-ray diffraction and differential-thermal analyses. The possibility of obtaining a variablecomposition phase Na1?x Mn1?x Cr1+x (MoO4)3 (0 ≤ x ≤ 0.5) and ternary molybdate NaMn3Cr(MoO4)5 was examined. The temperature dependence of the conductivity of the phase Na1?x Mn1?x Cr1+x (MoO4)3 was analyzed.  相似文献   

9.
The catalytic activity of framework phosphates of the general formula LiZr2(VO4)x(PO4)3–x with different degrees of phosphorus replacement (x = 0, 0.1, 0.3, 0.4, 0.6, and 0.8) was studied in methanol transformations in an inert atmosphere. It was shown that the ratio between the activity and selectivity of the catalysts in dehydration and dehydrogenation reactions is determined by their vanadium content and the process temperature.  相似文献   

10.
The subsolidus region of the Ag2MoO4-MgMoO4-Al2(MoO4)3 ternary salt system has been studied by X-ray phase analysis. The formation of new compounds Ag1 ? x Mg1 ? x Al1 + x (MoO4)3 (0 ≤ x ≤ 0.4) and AgMg3Al(MoO4)5 has been determined. The Ag1 ? x Mg1 ? x Al1 + x (MoO4)3 variable-composition phase is related to the NASICON type structure (space group R \(\bar 3\) c). AgMg3Al(MoO4)5 is isostructural to sodium magnesium indium molybdate of the same formula unit and crystallizes in triclinic system (space group P \(\bar 1\), Z = 2) with the following unit cell parameters: a = 9.295(7) Å, b = 17.619(2) Å, c = 6.8570(7) Å, α = 87.420(9)°, β = 101.109(9)°, γ = 91.847(9)°. The compounds Ag1 ? x Mg1 ? x Al1 + x (MoO4)3 and AgMg3Al(MoO4)5 are thermally stable up to 790 and 820°C, respectively.  相似文献   

11.
Temperature dependences of the electrical conductivity are studied in the range 4.2’300 K and Seebeck coefficient at room temperature of bulk samples of tungsten dichalcogenide polycrystals with niobium substitutions for tungsten and selenium substitutions for sulfur – W1–x Nb x (S1–y Se y )2. The two-dimensionalization of electron transport properties is detected at niobium concentrations x ≥ 0.1 in W1–x Nb x S2 and x ≥ 0.05 in W1–x Nb x Se2. In samples with additional partial selenium substitution for sulfur the electron transport remains three-dimensional. At room temperature the Seebeck coefficient (at equal electrical conductivities) is several times higher in the samples with quasi-two-dimensional transport than in the samples with three-dimensional transport. The calculation of the power factor at room temperature shows its nine times increase.  相似文献   

12.
A theoretical investigation of the reaction mechanism and kinetics of the reaction between chloromethanes CH4–xClx (x = 1–3) and chlorine atoms was performed. The height of the reaction barrier was found to decrease with the degree of substitution of chloromethanes with atomic chlorine. A direct dynamics method was employed to study the kinetic nature of these hydrogen-abstraction reactions. The sequence of calculated reaction rate coefficients is: k(CH3Cl + Cl) < k(CH2Cl2 + Cl) < k(CHCl3 + Cl).  相似文献   

13.
The hydrothermal reaction of a mixture of V2O5, VCl3, 2,5-pyridinedicarboxylic acid and diluted H2SO4 for 68 h at 180°C gives a blue colored solution which yields prismatic blue crystals of IV 2 IV O2(SO4)2(H2O)6] (1) in 32% yield (based on V). Complex 1 was investigated by means of elemental analysis (C, H and S), TGA, FT-IR, manganometric titration, Single Crystal X-ray Diffraction Methods and also comparative antimicrobial activities. Crystal data for the compound: monoclinic space group P21/c and unit cell parameters are a = 7.3850(12) Å, b = 7.3990(7) Å, c = 12.229(2) Å, β = 108.976(12)° and Z = 2. Although structure of 1 as a natural mineral has been previously determined, this work covers new preparation method and full characterization of 1 along with comparison of antibacterial activity between 1 and the commercial vanadium(IV) oxide sulfate hydrate compounds, VOSO4 · xH2O (Riedel-de Haën and Alfa Aesar brand names). 1 was evaluated for the antimicrobial activity against gram-positive, gram-negative bacteria, yeasts and mould compared with the commercial VOSO4 · xH2O compounds. 1 showed weak activity against bacteria Bacillus cereus, Nocardia asteroides and yeast Candida albicans. A good antimicrobial activity was recorded against Cirtobacter freundii (15 mm). There are only a few reproducible well-defined vanadium(IV) starting materials to use for exploring the synthesis of new materials. VCl4, VO(acac)2, VOSO4 · xH2O and [V(IV)OSO4(H2O)4] · SO4 · [H2N(C2H4)2NH2] are common starting materials for such applications. In addition to these compounds, 1 can be used as an oxovanadium precursor.  相似文献   

14.
The subsolidus phase composition of the M2O-CdO-V2O5 systems with M = Li or Na is studied. Double orthovanadates MCdVO4 and MCd4(VO4)3 form solid solutions of composition Li1 ? 2x/3Cd x/3CdVO4 (0 ≤ x ≤ 1, orthorhombic space group Cmcm, modulation at x = 0.6) and Na3 ? 2x Cd3 + x (VO4)3 (0 ≤ x ≤ 0.10 and 0.30 ≤ x ≤ 1, orthorhombic space group Cmcm and Pn21 a or Pnma, respectively). In the range 0.10 < x < 0.30, the end-members of the solid solutions coexist. Isothermal sections of the systems are mapped.  相似文献   

15.
Phase formation in the A1 + x Al x Ti2 ? x P3O12 (A = Li, Na, K, Rb, or Cs; 0 ≤ x ≤ 2.0) and B0.5(l + x)Al x Ti2 ? x P3O12 (B = Mg, Ca, Sr, or Ba; 0 ≤ x ≤ 2.0) systems was studied using X-ray powder diffraction, electron probe microanalysis, and IR spectroscopy. The following double and triple orthophosphates were found to exist: A1 + x Al x Ti2 ? x (PO4)3 with A = Li (0 ≤ x ≤ 0.3), Na (0 ≤ x ≤ 1.0), K (x = 0, 1.0, or 2.0), Rb (x = 0, 1.0, or 2.0), or Cs (0 ≤ x ≤ 1.0) and B0.5(l + x)Al x Ti2 ? x (PO4)3 with B = Mg and Ba (x = 0), Ca and Sr (0 ≤ x ≤ 0.2). These orthophosphates crystallize in the structure types of kosnarite, langbeinite, cesium titanium arsenate, potassium aluminum phosphate, or rubidium aluminum phosphate. Their crystal parameters were calculated. For CsTi2(PO4)3 (x = 0), Rietveld refinement was carried out: space group Ia \(\bar 3\) d, Z = 32, a = 19.909(5) Å, V = 7892(1) Å3. This compound has a framework structure. The framework is built of TiO6 octahedra and PO4 tetrahedra; eight- and 12-coordinated Cs+ cations populate interstices.  相似文献   

16.
Continuous substitutional solid solutions between cobalt and nickel phosphates with varied degree of anion protonation were obtained: Co1?x Ni x HPO4·1.5H2O and (Co1?x Ni x )3(PO4)2·8H2O, where 0 ≤ x ≤ 1.00. The thermolysis of the solid solutions was studied by the example of Co1?x Ni x HPO4·1.5H2O. The phases synthesized were compared with the previously described continuous solid solution Co1?x Ni x (H2PO4)2·2H2O.  相似文献   

17.
Investigations of solid state preparation of La1?xMnO3 compounds (x = 0, 0.1, 0.14, 0.17, 0.23) has revealed a number of intermediate structural states connected with progressive ordering of crystal structures. Freshly prepared non-stoichiometric compounds (x ≠ 0) are characterized by Mn4+ inclusion (0.09 ≤ y(Mn4+) 0.24) and rhombohedral space group \(R\bar 3c\).  相似文献   

18.
Compounds with compositions [Rh(H2O)6]2(SO4)3·4H2O (I), (H3O)[Rh(H2O)6](SO4)2 (II), [Rh(H2O)5OH](SO4)·0.5H2O (III), and [Rh(H2O)6]2(SO4)·(H2SO4) x ·5H2O (IV) have been studied. The crystal structures of II, III, and IV were determined. All compounds crystallized in the monoclinic crystal system. Crystal data for II: a = 7.279(2) Å, b = 10.512(7) Å, c = 15.806(3) Å, β = 96.71(3)°, space group P21/n, Z = 2, d calc = 2.334 g/cm3; III: a = 20.433(4) Å, b = 7.820(2) c = 11.215(2) Å, β = 114.14(1)°, space group C2/c, Z = 8, d calc = 2.559 g/cm3; IV: a = 6.2250(4 Å), b = 27.0270(12) Å, c = 7.2674(5) Å, β = 97.04(3)°, space group P21/c, Z = 4, d calc = 2.143 g/cm3. The compounds were studied by IR spectroscopy and powder X-ray diffraction. All of the isolated crystalline phases are sparingly soluble in ethanol and well soluble in water.  相似文献   

19.
Glassy Se100?x(Ge2Sb2Te5)x (x?=?5, 10, 15 and 20) bulk alloys were prepared by melt-quenched technique and studied by using differential scanning calorimetry at different heating rates under non-isothermal condition. The detailed thermal analysis shows that the glass transition temperature (Tg) depends on heating rates and x content. In particular, it is found that the glass-forming ability, thermal stability (Tc???Tg) and crystallization activation energy (Ec) increase with increased x content in amorphous Se, whereas glass transition activation energy (Eg) and fragility index (F) decrease with increased x contents. Variation in these parameters can be explained on the basis of network-forming ability of Se and bonding arrangement among the constituent atoms of alloys.  相似文献   

20.
The low-temperature heat capacity of Na2Lu (MoO4)(PO4) was measured by adiabatic calorimetry in the range of 7.47–345.74 K. The experimental data were used to calculate the thermodynamic functions of Na2Lu (MoO4)(PO4). At 298.15 K, the following values were obtained: C p 0 (298.15 K) = 237.7 ± 0.1 J/(K mol), S 0(298.15 K) = 278.1 ± 0.8 J/(K mol), H 0(298.15 K) ? H 0 (0 K) = 42330 ± 20 J/mol, and Φ0(298.15 K) = 136.1 ± 0. 3 J/(K mol). A heat capacity anomaly was found in the range of 10-67 K with a maximum at T tr = 39.18 K. The entropy and enthalpy of transition are ΔS = 12.39 ± 0.75 J/(K mol) and ΔH = 403 ± 16 J/mol. The thermal investigation of sodium lutetium molybdate phosphate in the high-temperature range (623–1223 K) was performed using differential scanning calorimetry. It was found that during melting in the range of 1030–1200 K, Na2Lu(MoO4)(PO4) degrades to simpler compounds; the degradation scenario is verified by X-ray powder diffraction.  相似文献   

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