P2O2-V2O5-TiO2的表面结构

P_2O_5-V_2O_5-TiO_2(简写为P-V-Ti)对芳烃氧化有良好的催化效果.丁烷氧化催化剂P-V体系的体相和表面结构已有一些报道.但P_2O_5对V-Ti的影响文献较少报道.本文用XRD,IR,TPD和ESR考察了P-V-Ti体系. 1.试剂和催化剂:草酸、偏钒酸铵、二氧化钛均为化学纯.将V_2O_5:TiO_2=11:89(重量)样品分别按 P/V原子比为0.1,0.3,0.6,1.0,1.5和2.5制成编号为P-0.1,P-0.3,P-O.6,P-1.0,P-1.5和P-2.5的催化剂.     

Structure of (C3H5NH3)2H2P2O7·H2O

The bis(cyclopropylammonium)dihydrogenodiphosphate monohydrate is a new diphosphate associated with the organic molecule C₃H₅NH₂. We report the chemical preparation and the crystal structure of this organic cation diphosphate. (C₃H₅NH₃)₂H₂P₂O₇.H₂O is orthorhombic (S.G. : P2₁2₁2₁), with Z = 4 and the following unit-cell parameters : a = 4.828(1) Å, b = 11.011(1) Å, c = 25.645(2) Å. The P₂O₇ groups and H₂O water molecules form a succession of bidimensional layers perpendicular to the c axis. The organic cations ensure the three-dimensional cohesion by NH-O hydrogen bonds.     

Phase diagram and IR spectral investigations of the 2TeO2 · V2O5Li2O · V2O5 · 2TeO2 system

By means of X-ray phase analysis, IR spectroscopy, and DTA, the system 2TeO₂ · V₂O₅Li₂O · V₂O₅ · 2TeO₂ was investigated and its phase diagram was constructed. The formation of a new compound with composition Li₂O · 3V₂O₅ · 6TeO₂, melting incongruently was documented. A comparison of the bands in the IR spectrum was made. Stable glasses in the whole range of concentrations were prepared. From the IR spectra of the glasses, the corresponding crystallization products, and the data of known crystal structures, a model of the short-range order in the glasses was proposed.     

P2O5掺杂的磷钨酸常温电解质

以磷钨酸(PWA)为基质,加入适量的P2O5,制备了P2O5/PWA电解质. 采用交流阻抗谱方法研究了不同质量分数P2O5电解质的导电性能及相对湿度对电导率的影响. 结果表明,质量分数为7%的P2O5/PWA电解质,室温电导率达到0.045 S/cm;相对湿度在20%～70%范围内电解质的电导率变化不大;在40 ℃下长时间放置,电解质的质量损失小于2%,表明其常温保水性好.     

Na2O—P2O5玻璃的结构和光学碱度

Duffy所提出的光学碱度概念,为研究固体物质的酸碱性,特别是冶金炉渣、玻璃等非晶态体系的碱度提供了一条新的途径.该方法所用计算光学碱度∧的公式为     

Phase Equilibria in The System La2O3–K2O–P2O5

The ternary system La₂O₃–K₂O–P₂O₅ has been examined by thermal, X-ray, IR and microscopic methods. The existence of three double potassium-lanthanum phosphates, K₃La(PO₄)₂, KLa(PO₃)₄ and K₂La(PO₃)₅ has been confirmed, and the phase diagram of the ternary system La₂O₃–K₂O–P₂O₅ over the composition range LaPO₄–K₃PO₄–P₂O₅ has been determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and crystal structure of the hydrated magnesium diphosphate Mg2P2O7·3.5H2O and its high temperature variant Mg2P2O7·H2O

The synthesis and crystal structure of a novel hydrated magnesium diphosphate and its high temperature variant are described. Both structures were solved from powder X-ray diffraction data. The room temperature variant with composition Mg₂P₂O₇·3.5H₂O crystallises in the monoclinic space group P2₁/c (No. 14) with a=10.9317(1), b=8.05578(9), c=9.2774(1) Å, β=90.201(1)°, V=816.99(2) ų and Z=4. The structure consists of sheets stacked along [100] which are linked through MgO₂(H₂O)₄ pillars into a three-dimensional framework with cavities containing water molecules. Within the sheets there are infinite edge-sharing chains of Mg octahedra along [010] which are cross linked by P₂O₇⁴⁻ groups. A high temperature variant exists around 200°C. The crystal structure of this compound with composition Mg₂P₂O₇·H₂O was solved and refined in the monoclinic space group C2/c (No. 15) with a=18.6596(4), b=7.9769(1), c=8.9757(2) Å, β=107.378(1)°, V=1275.01(4) ų, Z=8. The transformation to Mg₂P₂O₇·H₂O involves removal of the water molecules in the cavities and the water molecules of the Mg octahedral pillars in Mg₂P₂O₇·3.5H₂O. The sheets in Mg₂P₂O₇·3.5H₂O however remain unchanged during the transformation as the water molecule coordinating Mg here is retained. These sheets are linked through tetrahedral MgO₄ pillars into a three-dimensional structure containing infinite 10-membered ring channels along [001]. Both compounds have been further characterised by ³¹P MAS NMR spectroscopy, thermogravimetric analysis and high temperature powder X-ray diffraction.     

Phase equilibria in the oxide system Nd2O3–K2O–P2O5

A phase equilibria diagram of the partial system NdPO₄–K₃PO₄–KPO₃ has been developed as part of the research aimed at determining the phase equilibrium relationships in the oxide system Nd₂O₃–K₂O–P₂O₅. The investigations were conducted using thermoanalytical techniques, X-ray powder diffraction analysis and reflected-light microscopy. Three isopleths existing between: K₃Nd(PO₄)₂–K₄P₂O₇, NdPO₄–K₅P₃O₁₀ and NdPO₄–K₄P₂O₇ have been identified in the partial NdPO₄–K₃PO₄–KPO₃ system. Previously unknown potassium-neodymium phosphate “K₄Nd₂P₄O₁₅” has been discovered in the latter isopleth section. This phosphate exists in the solid phase up to a temperature of 890 °C at which it decomposes into the parent phosphates NdPO₄ and K₄P₂O₇. Four invariant points: two quasi-ternary eutectics, E₁ (1057 °C) and E₂ (580 °C) and two quasi-ternary peritectics, P₁ (1078 °C) and P₂ (610 °C), occur in the NdPO₄–K₃PO₄–KPO₃ region.     

Kinetics of nonisothermal crystallization of Cs2O–Fe2O3–P2O5 glasses

The crystallization kinetics of Cs₂O–Fe₂O₃–P₂O₅ glasses containing 12.5–27 mol% Cs₂O were studied by using differential scanning calorimetry under nonisothermal conditions. Strong dependence of activation energy with temperature was observed, indicating the complex nature of the crystallization process. The various crystallization products were identified by X-ray diffraction technique. CsFeP₂O₇ was found to be the major crystalline phase in all cases. The overall activation energy obtained by classical model-free kinetic method was compared with that of isoconversional method; and from the results, the dependence of activation energy on extent of reaction and average temperature was delineated.     

Cyclization of monoethanolamine to aziridine over Cs2O–P2O5/SiO2

Several commercially available supports were examined for cyclization of monoethanolamine to aziridine, and SiO₂ was found to yield the best results. The obtained results indicated that selectivity of aziridine was mainly influenced by support. The catalysts were characterized by NH₃-TPD and XRD. It was found that SiO₂ with lower acidity could inhibit the intermolecular condensations, and thus favored the formation of aziridine. The Cs₄P₂O₇ phase was confirmed as the active site in the supported cesium phosphate catalyst. The reaction parameters were also optimized and a yield of 52% aziridine was obtained over 200?h. Thus, a continuous process for the cyclization of monoethanolamine to aziridine has been established.     

Raman spectroscopic study of CuO–V2O5–P2O5–CaO glass system

In order to evidence the structural changes induced by CuO and V₂O₅ in the phosphate glass network and their modifier or former role, x(CuO·V₂O₅)(100 − x)[P₂O₅·CaO] glass system was prepared and investigated using Raman spectroscopy (0 ≤ x ≤ 40 mol%).Raman spectra of the studied glasses present the specific bands of the phosphate glasses at low concentration of transition metal (TM) ions, but at higher concentration (x > 7 mol%) a strong depolymerization of the phosphate network appears; non-bridging oxygen atoms are involved in VOP and CuOP bonds and new short units are formed. For a high concentration of V₂O₅ (x > 10 mol%) the Raman bands of V₂O₅ prevail in the spectra; this fact suggests that vanadium oxide imposes its structural units in the network acting thus as a network glass former.2D correlation analysis was also applied for the concentration-dependent Raman spectra in order to verify the assignments of the vibration modes and to find correlations in the changes induced by TM ions content. 2D correlation maps indicate a good correlation between the bands at ∼705 cm⁻¹ assigned to POP stretching vibration and at ∼1175 cm⁻¹ assigned to PO₂ groups which suggest the depolymerization of the phosphate network. The correlation between the 1270 cm⁻¹ and 930 cm⁻¹ bands also suggests that V₂O₅ oxide is responsible for PO bonds breaking and POV formation.     

209Bi NQR in Mixed Oxides 2Bi2O3· B2O3, 3Bi2O3· 5B2O3, and Bi2O3· 3B2O3

It was earlier found from nuclear quadrupole resonance (NQR) measurements and computer modeling that -Bi₂O₃, Bi₃O₄Br and mixed oxides Bi₂O₃· 2Al₂O₃, Bi₂O₃· 2Ga₂O₃, Bi₂O₃· 3GeO₂, and 2Bi₂O₃· 3GeO₂exhibit local ordered magnetic fields from 30 to 200 G. It thus follows that these compounds are not diamagnets in a conventional sence of the word. With the aim of revealing previously unknown magnetic properties in bismuth(III) oxide-based Main Group element compounds, the mixed bismuth–boron oxides 2Bi₂O₃· B₂O₃, 3Bi₂O₃· 5B₂O₃, and Bi₂O₃· 3B₂O₃were prepared and studied using ²⁰⁹Bi NQR. The quadrupole interactions of the ²⁰⁹Bi nuclei and their electronic environment were studied, the crystallochemical features of the compounds were discussed, and the conformity of the ²⁰⁹Bi results to the X-ray structure data was verified. The preliminary tests in the field of a permanent magnet showed that the resonance intensities increase in external magnetic fields, indicating that a magnetism of unknown nature develops in the titled compounds. It was found reasonable to continue studies of the magnetic properties of these compounds using single-crystal ²⁰⁹Bi NQR in external magnetic fields.     

Thermal Dehydration and Infrared Studies of Mg 2 P 2 O 7 · 6H 2 O Diphosphate

The thermal dehydration of Mg 2 P 2 O 7 ·; 6H 2 O were studied, in the range 25-800°;C, by thermogravimetric analysis (TG-DSC), x-ray diffraction, and infrared spectroscopy. According to the TG-DSC curves, the dehydration of this salt takes place in two stages. The results of thermal analysis, x-ray patterns, and infrared spectra of this compound heated at different temperatures showed that, after dehydration, Mg 2 P 2 O 7 ·; 6H 2 O decomposes into dihydrate Mg 2 P 2 O 7 ·; 2H 2 O diphosphate then to an amorphous Mg 2 P 2 O 7 product which crystallises at 665°;C to give anhydrous diphosphate f Mg 2 P 2 O 7 . The j H enthalpy of the dehydration of Mg 2 P 2 O 7 ·; 6H 2 O and of the formation of f Mg 2 P 2 O 7 have been calculated from thermogravimetric data. The infrared spectroscopic study of Mg 2 P 2 O 7 ·; 6H 2 O and of its heated products, reveals the existence of the characteristic bands of the P 2 O 7 group ( x as POP and x s POP) and showed that the POP angle is bent in these salts. In these compounds, the POP angle values are estimated using the Lazarev's relationship.     

Thermodynamic properties of two zinc borates: 3ZnO·3B2O3·3.5H2O and 6ZnO·5B2O3·3H2O

Two pure zinc borates with microporous structure 3ZnO·3B₂O₃·3.5H₂O and 6ZnO·5B₂O₃·3H₂O have been synthesized and characterized by XRD, FT-IR, TG techniques and chemical analysis. The molar enthalpies of solution of 3ZnO·3B₂O₃·3.5H₂O(s) and 6ZnO·5B₂O₃·3H₂O(s) in 1 mol · dm⁻³ HCl(aq) were measured by microcalorimeter at T = 298.15 K, respectively. The molar enthalpies of solution of ZnO(s) in the mixture solvent of 2.00 cm³ of 1 mol · dm⁻³ HCl(aq) in which 5.30 mg of H₃BO₃ were added were also measured. With the incorporation of the previously determined enthalpy of solution of H₃BO₃(s) in 1 mol · dm⁻³ HCl(aq), together with the use of the standard molar enthalpies of formation for ZnO(s), H₃BO₃(s), and H₂O(l), the standard molar enthalpies of formation of −(6115.3 ± 5.0) kJ · mol⁻¹ for 3ZnO·3B₂O₃·3.5H₂O and −(9606.6 ± 8.5) kJ · mol⁻¹ for 6ZnO·5B₂O₃·3H₂O at T = 298.15 K were obtained on the basis of the appropriate thermochemical cycles.     

Thermal transformations of α-H6P2Mo18O62·nH2O heteropolyacid

According to the ³¹P NMR spectroscopy, heteropolyacid (HPA) H₆P₂Mo₁₈O₆₂·nH₂O (P₂Mo₁₈), -isomer of the Dawson structure, transforms upon heating above 80 °C partially (up to 30%) to -isomer, in which both polar groups Mo₃O₁₃ of the heteropolyanion are turned by 60° around the N₃ axis, and partially to -isomer in which only one group is turned. The - and -isomers of P₂Mo₁₈ have been found for the first time. Their transformation into the -isomer occurs upon rehydration in one week in air and in 1 h in an aqueous solution. HPA P₂Mo₁₈ decomposes on heating up to 350 °C to HPA H₃PMo₁₂O₄₀ (PMo₁₂) and a previously unknown phase of the HPMo₆I₂₁ composition, which in its turn decomposes at 375 °C to molybdenyl phosphates and IiI₃. The PMo₁₂ decomposition occurs via two routes to form the same products at temperatures of 400 and 450 °C with corresponding exotherms of IiI₃ crystallization.     

50℃时P2O5-MgO-NH3-H2O四元体系相平衡研究

本文测定了P2O5-MgO-NH3-H2O四元体系在50℃时的相平衡数据, 绘出了干盐相图。应用Pitzer电解质溶液理论进行了活度系数关联, 计算了所研究体系在50℃的相平衡数据。     

超分子化合物(bipyH2)2(H2P2Mo5O23)·H2O的水热合成、晶体结构和性质

在水热条件下合成了新型超分子化合物(bipyH2)2(H2P2Mo5O23)*H2O, 对其进行了红外光谱、拉曼光谱、紫外-可见漫反射光谱、荧光光谱和循环伏安等分析表征. X射线单晶结构分析表明, 标题化合物属单斜晶系, P21/c空间群, 晶胞参数a=1.679 51(7) nm, b=1.151 93(4) nm, c=1.889 08(8) nm, β=108.335(1) °, V=3.469 2(2) nm3, Z=4, Dc=2.382 g/cm3, F(000)=2 408, μ=1.951 mm-1, R=0.024 4, Rw＝0.072 1. 标题化合物的杂多阴离子[P2Mo5O23]4-由5个MoO6畸变的八面体和2个PO4畸变四面体通过共顶点或共边组成; 5个Mo原子近似处于同一平面, 它们和2个P原子组成了一个畸变的五角双锥构型; 杂多阴离子与质子化的4,4′-bipy和水分子通过氢键连成无限二维网状结构, 形成超分子化合物.     

Neutron diffraction study of Na2UO2(C2O4)2 · 5D2O

A sample of Na₂UO₂(C₂O₄)₂ · 5D₂O (I) was studied by powder neutron diffraction. The compound crystallizes in the triclinic system, space group P1, unit cell parameters: a = 6.934(1) ?, b = 7.566(1) ?, c = 15.409(2) ?, ?? = 94.720(6)°, ?? = 96.281(6)°, ?? = 111.765(5)°, Z = 2, R _F = 5.35, R _I = 6.73 and ??² = 2.89. The hydrogen bonds and non-valence contacts involved in the formation and binding of the {Na₂[UO₂(C₂O₄)₂(D₂O)](D₂O)₄} layers in I were analyzed using the Voronoi-Dirichlet polyhedra.