共查询到20条相似文献,搜索用时 15 毫秒
1.
G. V. Zimina M. A. Zhuravleva I. N. Smirnova F. M. Spiridonov A. V. Novoselov A. L. Il’inskii 《Russian Journal of Inorganic Chemistry》2009,54(12):1992-1997
The 950°C isothermal section of the ScPO4-Na3PO4-Li3PO4 three-component system was plotted and studied; one-, two-, and three-phase fields were bounded. Three solid solution fields
exist in the title system: one based on LiNa5(PO4)2 complex phosphate (olympite structure), another on scandium-stabilized high-temperature Na3PO4 phase Na3(1 − x)Sc
x/3□2/3x
PO4 (space group Fm3m), and the third on Na3Sc2(PO4)3 (NASICON structure). All phases found in the title system are derivatives of phases that exist in its subsystems. Lithium-for-sodium
isovalent substitutions in Na3Sc2(PO4)3 considerably increase the NASICON-type solid solution field but negatively influence the conductivity of the phase. 相似文献
2.
Zh. A. Kochkarov M. V. Khubaeva Z. L. Khakulov 《Russian Journal of Inorganic Chemistry》2011,56(5):783-786
This is the first study of the NaBO2-Na2CO3-Na2MoO4-Na2WO4 quaternary system by differential thermal analysis. Na2[MoO4(x)WO4(1 − x)] solid solutions in the quaternary system are found to not decompose. 相似文献
3.
M. M. Godneva D. L. Motov M. P. Rys’kina 《Russian Journal of Inorganic Chemistry》2011,56(9):1363-1369
The ZrO(NO3)2-H3PO4-CsF-H2O system was studied at 20°C along the section at a molar ratio of PO43−/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO2 concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated
for the first time: crystalline fluorophosphates CsZrF2PO4 · H2O, amorphous oxofluorophosphate Cs2Zr3O2F4(PO4)2 · 3H2O, and amorphous oxofluorophosphate nitrate CsZr3O1.25F4(PO4)2(NO3)0.5 · 4.5H2O. The compound Cs3Zr3O1.5F6(PO4)2 · 3H2O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following
new compounds was established: Cs2Zr3O1.5F5(PO4)2 · 2H2O, Cs2Zr3F2(PO4)4 · 4.5H2O, and Zr3O4(PO4)1.33 · 6H2O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical,
thermal, and IR spectroscopic analyses. 相似文献
4.
O. V. Sinitsyna A. G. Veresov E. S. Kovaleva Yu. V. Kolen’ko V. I. Putlyaev Yu. D. Tretyakov 《Russian Chemical Bulletin》2005,54(1):79-86
Conditions for hydroxyapatite (HAP) synthesis in aqueous solutions by hydrolysis of α-Ca3(PO4)2 were studied. Temperature exerts a substantial effect on the rate of α-Ca3(PO4)2 hydrolysis and also changes the morphology of the reaction products. At 40 °C, the plate-like intersecting (perpendicular to the surface of the initial particles) crystals of HAP grow. Their maximum size after the 24-h hydrolysis is 1–2 µm. Needle like HAP crystals are formed upon boiling of the suspension. The morphology observed for the HAP particles agrees well with the conclusions obtained by analysis of the kinetics of tricalcium phosphate hydrolysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 78–85, January, 2005. 相似文献
5.
The interaction between two similar plane double-layers for Mg3(PO4)2 type asymmetric electrolytes was investigated with the aid of λ parameter method. The interaction energies for the system
at positive surface potential were expanded in power series at low and high potential, respectively. The accurate numeral
results and V′-ξ
d
curves were given for y
0 ≤ 20 and they can be used to check up the validity of approximate expressions obtained. When y
0 ≥ 5, V′ hardly changes with y
0. The interaction energies between two similar plane parallel double layers for symmetric and asymmetric electrolytes at y
0 = 1 were compared; when ξ
d
is small, the interaction energies for Mg3(PO4)2 type electrolytes increase more drastically than for other type electrolytes. The present results are also fit for Al2(SO4)3 type asymmetric electrolytes at negative surface potential.
The article is published in the original. 相似文献
6.
I. A. Leonidov L. L. Surat O. N. Leonidova 《Russian Journal of Inorganic Chemistry》2011,56(11):1706-1712
Phase equilibria in the Ca3(VO4)2-K3VO4-NdVO4 system have been studied. An extensive calcium orthovanadate-based solid solution was found to form with the boundary compositions
as follows: Ca3(VO4)2-Ca9Nd(VO4)7-Ca9.33K2.33(VO4)7-Ca7.88K2.63Nd0.87(VO4)7. The unit cell parameters of the whit-lockite vanadates synthesized increase as the potassium and neodymium contents increase.
Phase transitions from the low-temperature β phase to the β′ centrosymmetrical structure in Ca9.33 − 5z
K2.33 + z
Nd3z
(VO4)7 vanadates have been studied dilatometrically. The increase in the β ai β′ transition temperature caused by potassium is interpreted
as arising from the filling in of vacant cation positions M(4) and M(6). 相似文献
7.
A. M. Potapova G. V. Zimina I. N. Smirnova A. V. Novoselov F. M. Spiridonov S. Yu. Stefanovich 《Russian Journal of Inorganic Chemistry》2008,53(2):174-180
Subsolidus sections in the systems Li3PO4-InPO4 (950°C) and Na3PO4-InPO4 (800, 900, and 1000°C) have been studied by X-ray powder diffraction. The compound Li3In(PO4)2 has been synthesized, and the nasicon-type solid solution Li3(1 ? x)In2 + x(PO4)3 (0.67 ≤ x ≤ 0.80). has been found to exist. In the system Na3PO4-InPO4, the solid solution Na3(1 ? x)Inx/3PO4 (0 ≤ x ≤ 0.2) and two complex phosphates exist: Na3In(PO4)2 and Na3In2(PO4)3. These complex phosphates are dimorphic, with the irreversible-transition temperature equal to 675 and 820°C, respectively. Na3In(PO4)2 degrades at 920°C. Ionic conductivity has been measured in some phases in the system. 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.
S. Y. Yang S. Zhang B. L. Fu Q. Wu F. L. Liu C. Deng 《Journal of Solid State Electrochemistry》2011,15(11-12):2633-2638
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
10.
Ben Hui Wang Ji De Wang RuiQuan Liu Ya Hong Xie Zhi Jie Li 《Journal of Solid State Electrochemistry》2007,11(1):27-31
A new type of oxide–salt composite electrolyte, yttrium doped ceria YDC–Ca3(PO4)2–K3PO4, was developed and demonstrated for its promising use for ammonia synthesis. Using this composite electrolyte, ammonia was
synthesized from nitrogen and natural gas at atmospheric pressure in the solid-state proton conducting cell reactor, and the
optimal condition for ammonia production was determined . The evolved rate of ammonia is up to 6.95×10−9 mol s−1 cm−2. 相似文献
11.
The interaction energies between two double layers for FeCl3 or Na3PO4 type electrolytes at y
0 > 0 >y
d>—y
0 were calculated with the aid of 7n parameter methods and the accurate numeral results were given when the dimensionless surface
potential of two double layers changes from -20 to +20. When ∣y
d∣ > 5, the absolute value of the interaction energies, ∣V’∣, for FeCl3 type electrolytes at y
0= 1 stops to increase. When y
0> 8, the ∣V’∣ for FeCl3 type electrolytes at y
d= -1 ceases to change. The influence of y
d on ∣V’∣ for FeCl3 type electrolytes is more significant than the influence of y
0. The variation of ∣V’∣ with y
d and y
0 for Na3PO4 type electrolytes is opposite to that for FeCl3 type electrolytes. The interaction energies between two dissimilar double layers for Na2SO4, CaCl2, NaCl, Na3PO4 and FeCl3 type electrolytes at y
0= 1 and y
d = -10 are compared and the results indicate that the interaction energies close to each other for FeCl3 and CaCl2 type electrolytes and for Na3PO4 and Na2SO4 type electrolytes, respectively. ∣V’∣ increases with the raises of y
0 or ∣y
d∣, but decreases with the raises of z
+ or z
-. 相似文献
12.
Summary. Calcium sulfate occurs in nature in form of three different minerals distinguished by the degree of hydration: gypsum (CaSO4·2H2O), hemihydrate (CaSO4·0.5H2O) and anhydrite (CaSO4). On the one hand the conversion of these phases into each other takes place in nature and on the other hand it represents
the basis of gypsum-based building materials. The present paper reviews available phase diagram and crystallization kinetics
information on the formation of calcium sulfate phases, including CaSO4-based double salts and solid solutions.
Uncertainties in the solubility diagram CaSO4–H2O due to slow crystallization kinetics particularly of anhydrite cause uncertainties in the stable branch of crystallization.
Despite several attempts to fix the transition temperatures of gypsum–anhydrite and gypsum–hemihydrate by especially designed
experiments or thermodynamic data analysis, they still vary within a range from 42–60°C and 80–110°C. Electrolyte solutions
decrease the transition temperatures in dependence on water activity.
Dry or wet dehydration of gypsum yields hemihydrates (α-, β-) with different thermal and re-hydration behaviour, the reason
of which is still unclear. However, crystal morphology has a strong influence.
Gypsum forms solid solutions by incorporating the ions HPO4
2−, HAsO4
2−, SeO4
2−, CrO4
2−, as well as ion combinations Na+(H2PO4)− and Ln3+(PO4)3−. The channel structure of calcium sulfate hemihydrate allows for more flexible ion substitutions. Its ion substituted phases
and certain double salts of calcium sulfate seem to play an important role as intermediates in the conversion kinetics of
gypsum into anhydrite or other anhydrous double salts in aqueous solutions. The same is true for the opposite process of anhydrite
hydration to gypsum. Knowledge about stability ranges (temperature, composition) of double salts with alkaline and alkaline
earth sulfates (esp. Na2SO4, K2SO4, MgSO4, SrSO4) under anhydrous and aqueous conditions is still very incomplete, despite some progress made for the systems Na2SO4–CaSO4 and K2SO4–CaSO4–H2O.
Corresponding author. E-mail: daniela.freyer@chemie.tu-freiberg.de
Received December 17, 2002; accepted January 10, 2003
Published online April 3, 2003 相似文献
13.
Xin Zhang Suqin Liu Kelong Huang Shuxin Zhuang Jun Guo Tao Wu Ping Cheng 《Journal of Solid State Electrochemistry》2012,16(3):937-944
The macroporous Li3V2(PO4)3/C composite was synthesized by oxalic acid-assisted carbon thermal reaction, and the common Li3V2(PO4)3/C composite was also prepared for comparison. These samples were characterized by X-ray diffraction (XRD), scanning electron
microscope (SEM), and electrochemical performance tests. Based on XRD and SEM results, the sample has monoclinic structure
and macroporous morphology when oxalic acid is introduced. Electrochemical tests show that the macroporous Li3V2(PO4)3/C sample has a high initial discharge capacity (130 mAh g−1 at 0.1 C) and a reversible discharge capacity of 124.9 mAh g−1 over 20 cycles. Moreover, the discharge capacity of the sample is still 91.5 mAh g−1, even at a high rate of 2 C, which is better than that of the sample with common morphology. The improvement in electrochemical
performance should be attributed to its improved lithium ion diffusion coefficient for the macroporous morphology, which was
verfied by cyclic voltammetry and electrochemical impedance spectroscopy. 相似文献
14.
V. I. Pet’kov I. A. Shchelokov M. D. Surazhskaya K. K. Palkina A. S. Kanishcheva A. V. Knyazev 《Russian Journal of Inorganic Chemistry》2010,55(9):1352-1355
Double phosphate Ba1.5Fe2(PO4)3 was synthesized and structurally studied. Single crystals were synthesized by the fusion method. Cubic crystals, Z = 4, space group P213, a = 9.866(1) Å. This structure is built of polyhedrons of four types: PO4 tetrahedrons, two virtually regular FeO6 octahedrons, BaO12 twelve-vertex polyhedrons, and BaO9 nine-vertex polyhedrons. These polyhedrons share common oxygen vertices to form three-dimensional [Fe2(PO4)3]3∞ framework containing barium atoms in cavities. 相似文献
15.
M. Chromčíková M. Rodová K. Nitsch M. Liška 《Journal of Thermal Analysis and Calorimetry》2010,102(3):961-964
Structural relaxation of scintillating Ce-doped Na–Gd phosphate glass with a nominal composition of Ce:NaGd(PO3)4 was experimentally studied using non-isothermal thermo-mechanical analysis, and the relaxation process was described by the
Tool–Narayanaswamy–Mazurin model. The distribution of relaxation times was expressed by the empirical Kohlrausch–Williams–Watts
relaxation function with relaxation time directly proportional to dynamic viscosity. The model parameters and material constants
were obtained by the nonlinear regression analysis of thermo-mechanical data. It has been concluded that the model used of
structural relaxation correctly describes relaxation processes in studied Ce-doped NaGd(PO3)4 glass. 相似文献
16.
Phosphates M0.5Ti2(PO4)3 (M = Ni, Zn) were synthesized by the sol-gel method and characterized by the methods of X-ray diffraction, IR spectroscopy, and electronic microprobe analysis. Structures of Ni0.5Ti2(PO4)3 and Zn0.5Ti2(PO4)3 were studied by Rietveld method using the X-ray powder diffraction data. 相似文献
17.
A series of Li3V2(PO4)3/C composites with different amounts of carbon are synthesized by a combustion method. The physical and electrochemical properties of the Li3V2(PO4)3/C composites are investigated by X-ray diffraction, element analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and electrochemical measurements. The effects of carbon content of Li3V2(PO4)3/C composites on its electrochemical properties are conducted with cyclic voltammetry and electrochemical impedance. The experiment results clearly show that the optimal carbon content is 4.3 wt %, and more or less amount of carbon would be unfavorable to electrochemical properties of the Li3V2(PO4)3/C electrode materials. The results would provide some basis for further improvement on the Li3V2(PO4)3 electrode materials. 相似文献
18.
Dhanpat Rai Dean A. Moore Andrew R. Felmy Kevin M. Rosso Harvey BoltonJr. 《Journal of solution chemistry》2010,39(6):778-807
To determine the solubility product of PuPO4(cr, hyd.) and the complexation constants of Pu(III) with phosphate and EDTA, the solubility of PuPO4(cr, hyd.) was investigated as a function of: (1) time and pH (varied from 1.0 to 12.0), and at a fixed 0.00032 mol⋅L−1 phosphate concentration; (2) NaH2PO4 concentrations varying from 0.0001 mol⋅L−1 to 1.0 mol⋅L−1 and at a fixed pH of 2.5; (3) time and pH (varied from 1.3 to 13.0) at fixed concentrations of 0.00032 mol⋅L−1 phosphate and 0.0004 mol⋅L−1 or 0.002 mol⋅L−1 Na2H2EDTA; and (4) Na2H2EDTA concentrations varying from 0.00005 mol⋅L−1 to 0.0256 mol⋅L−1 at a fixed 0.00032 mol⋅L−1 phosphate concentration and at pH values of approximately 3.5, 10.6, and 12.6. A combination of solvent extraction and spectrophotometric
techniques confirmed that the use of hydroquinone and Na2S2O4 helped maintain the Pu as Pu(III). The solubility data were interpreted using the Pitzer and SIT models, and both provided
similar values for the solubility product of PuPO4(cr, hyd.) and for the formation constant of PuEDTA−. The log 10 of the solubility product of PuPO4(cr, hyd.) [PuPO4(cr, hyd.)
\rightleftarrows\rightleftarrows
Pu3++PO43-\mathrm{Pu}^{3+}+\mathrm{PO}_{4}^{3-}] was determined to be −(24.42±0.38). Pitzer modeling showed that phosphate interactions with Pu3+ were extremely weak and did not require any phosphate complexes [e.g., PuPO4(aq), PuH2PO42+\mathrm{PuH}_{2}\mathrm{PO}_{4}^{2+}, Pu(H2PO4)2+\mathrm{Pu(H}_{2}\mathrm{PO}_{4})_{2}^{+}, Pu(H2PO4)3(aq), and Pu(H2PO4)4-\mathrm{Pu(H}_{2}\mathrm{PO}_{4})_{4}^{-}] as proposed in existing literature, to explain the experimental solubility data. SIT modeling, however, required the inclusion
of PuH2PO42+\mathrm{PuH}_{2}\mathrm{PO}_{4}^{2+} to explain the data in high NaH2PO4 concentrations; this illustrates the differences one can expect when using these two different chemical models to interpret
the data. Of the Pu(III)-EDTA species, only PuEDTA− was needed to interpret the experimental data over a large range of pH values (1.3–12.9) and EDTA concentrations (0.00005–0.256 mol⋅L−1). Calculations based on density functional theory support the existence of PuEDTA− (with prospective stoichiometry as Pu(OH2)3EDTA−) as the chemically and structurally stable species. The log 10 value of the complexation constant for the formation of PuEDTA− [
Pu3++EDTA4-\rightleftarrows PuEDTA-\mathrm{Pu}^{3+}+\mathrm{EDTA}^{4-}\rightleftarrows \mathrm{PuEDTA}^{-}] determined in this study is −20.15±0.59. The data also showed that PuHEDTA(aq), Pu(EDTA)45-\mathrm{Pu(EDTA)}_{4}^{5-}, Pu(EDTA)(HEDTA)4−, Pu(EDTA)(H2EDTA)3−, and Pu(EDTA)(H3EDTA)2−, although reported in the literature, have no region of dominance in the experimental range of variables investigated in
this study. 相似文献
19.
V. I. Pet’kov A. S. Dmitrienko M. V. Sukhanov A. M. Koval’skii E. Yu. Borovikova 《Russian Journal of Inorganic Chemistry》2016,61(5):623-629
The NaFeZr(PO4)2SO4 and Pb2/3FeZr(PO4)7/3(SO4)2/3 sulfate phosphates with the NaZr2(PO4)3 (NZP) structure were synthesized and studied using X-ray diffraction, electron microprobe analysis, IR spectroscopy, and simultaneous differential thermal and thermogravimetric analysis. The phase formation and thermal stability of the compounds were studied by powder X-ray diffraction and DTA–TG. The Pb2/3FeZr(PO4)7/3(SO4)2/3 structure was refined by full-profile analysis. The structure framework is composed of randomly occupied (Fe,Zr)O6 octahedra and (P,S)O4 tetrahedra; the Pb2+ ions occupy extra-framework sites. The thermal expansion of Pb2/3FeZr(PO4)7/3(SO4)2/3 in the temperature range from–120 to 200°C was studied by temperature X-ray diffraction. In terms of the average linear coefficient of thermal expansion (αav = 1.7 × 10–6°C–1), this compound can be classified as having low expansion. The combination of different tetrahedral anions (a phosphorus and a smaller sulfur one) in the NZP resulted in a decrease in the framework size and cavities and enabled the preparation of low-expansion sulfate phosphate with a smaller extra-framework cation (cheap Pb) instead of larger cations (Cs, Ba, Sr) used most often in the monoanionic phosphates. 相似文献
20.
Zhang Shimin 《Colloid Journal》2008,70(2):168-177
The interactions between two similar plane double-layers for Na3PO4 type asymmetric electrolytes are described using hyperelliptic integrals. The mathematical treatments of hyperelliptic integrals
are much more difficult than those of elliptic integrals. The system was successfully treated with the aid of the λ parameter
method. The interaction energies for the system at positive surface potential are expanded in power series at low, moderate,
and high potentials, respectively. The accurate numeral results and V′-ξ
d
curves are given for y
0 ≤ 20 and can be used to check the validity of approximate expressions obtained. When y
0 ≥ 5, V′ hardly changes with y
0. The interaction energies between two similar plane parallel double layers for symmetric and asymmetric electrolytes at y
0 = 1 were compared; when ξ
d
→ 0, the interaction energies for Na3PO4 type electrolytes are much larger than for electrolytes of other types. The present results are also fit for FeCl3-type asymmetric electrolytes at negative surface potential.
The text was submitted by the author in English. 相似文献