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1.
《Journal of solid state chemistry》1987,69(1):126-134
In the system Na3PO4Na2SO4, the high-temperature, cubic γ form of Na3PO4 forms an extensive range of solid solutions: Na3−x(P1−xSx)O4, 0 < x < (0.57 to 0.70, depending on temperature). For compositions in the range x = ca. 0.33 to 0.57, these γ solid solutions are thermodynamically stable at all temperatures. The conductivity of the γ solid solutions increases with increasing x and reaches a maximum at x = 0.5 to 0.6, with values of 2 × 10−5 ohm−1 cm−1 at 100°C, rising to 1.3 × 10−2 ohm−1 cm−1 by 300°C; this conductivity increase with x is attributed to an increase in the sodium ion vacancy concentration, associated with the solid solution mechanism Na + PS. The phase diagram for the system Na3PO4Na2SO4 is given together with lattice parameters of the γ solid solutions. 相似文献
2.
Magdy A. M. Ibrahim Hamdy H. Hassan Sayed S. Abd El Rehim Mohamed A. Amin 《Journal of Solid State Electrochemistry》1999,3(7-8):380-386
The electrochemical behaviour of polycrystalline silver electrodes in Na2CO3 solutions was studied under potentiodynamic and potentiostatic conditions and complemented with X-ray diffraction analysis.
Potentiodynamic E/i anodic curves exhibit active passive transition prior to an oxygen evolution reaction. The active region involves a small
peak AI followed by a major peak AII before the passive region. Peak AI is assigned to the formation of an Ag2O layer while peak AII is due to the formation of an Ag2CO3 layer. The height of the anodic peaks increases with increasing Na2CO3 concentration, scan rate and temperature. The effect of increasing additions of NaClO4 on the electrochemical behaviour of Ag in Na2CO3 solutions was investigated. The perchlorate ions stimulate the active dissolution of Ag, presumably as a result of the formation
of soluble AgClO4 salt. In the passive region, ClO−
4 ions tend to break down the dual passive film, leading to pitting corrosion at a certain critical pitting potential. The
pitting potential decreases with ClO−
4 concentration. Potentiostatic current/time transients showed that the formation of Ag2O and Ag2CO3 layers involves a nucleation and growth mechanism under diffusion control. However, in the presence of ClO−
4 ions, the incubation time for pit initiation decreases on increasing the anodic potential step.
Received: 3 July 1998 / Accepted: 10 March 1999 相似文献
3.
《Journal of solid state chemistry》1987,67(1):58-63
Solid solutions (CrxFe1−x)VO4 can be prepared over a wide composition range and are thermally stable to above 900°C. They are isomorphous with α-MnMoO4 rather than adopting the CrVO4 or FeVO4 structures. At 3000 atm pressure, a reversible transformation to a CrVO4 type polymorph takes place. substitution of small amounts of phosphate into CrVO4 also produces an α-MnMoO4 isomorph. 相似文献
4.
《Journal of solid state chemistry》1986,65(3):293-300
Sodium ion motion in Na1+xZr2−xInx(PO4)3 Nasicon-related materials (0 ≤ x ≤ 1.85) has been studied by NMR at two resonance frequencies from 170 to 450 K. At 8 MHz the resonance lines due to M1- and M2-type sites are well resolved. They are split by a strong second-order quadrupolar effect (νQ = 1.5 Megacycles (Mc)/sec). For NaZr2(PO4)3 only the M1 site is occupied at RT, while a new site M5 appears at rising temperature (410 K). At 21 Mc/sec the line narrowing observed at increasing temperature illustrates the Na+ ion mobility within the skeleton. According to the temperature and the value of the ionic conductivity two diffusion mechanisms seem to occur. 相似文献
5.
New potassium-conducting solid electrolytes of the K3 ? 2x Cd x PO4 system are synthesized and studied. A wide range of solid solutions reaching x ≈ 0.35 with the structure of high-temperature modification of potassium orthophosphate forms in the system. An addition of cadmium ions leads to an abrupt increase in the K3PO4 conductivity due to the formation of potassium vacancies. The highest conductivity is approximately 10?2 S cm?1 at 300°C and above 10?1 S cm?1 at 700°C. 相似文献
6.
《Journal of Inorganic and Nuclear Chemistry》1981,43(2):375-378
Distribution coefficients for Fe(III) have been determined in the liquid-liquid extraction system Primene JM-T-toluene vs aqueous ammonium sulfate (and sodium sulfate) as a function of sulfate, acid, Fe(III) and amine sulfate concentrations. A study of loading equilibria as a function of time for this system indicates that equilibrium was largely achieved in 1 hr although some changes, possibly in the nature of the extracted species, occur up to approx. 20 hr. Extraction isotherms show a slope of 1 at low loadings, indicating the same degree of self association in both organic and aqueous phases, while the amine sulfate/iron ratio appears to approach 2.5 ± 0.25 at saturation loading. Results obtained by varying the sulfate concentration matrix indicates the formation of an aqueous complex of ferric ammonium sulfate which depresses iron distribution to the organic phase. The degree of aggregation of the amine sulfate, derived from iron distribution coefficient dependence on amine sulfate concentration data, is shown to be approx. 10. 相似文献
7.
The behavior of the metals in the Pt−Pd/ZrO2 and Pt−Pd/SO4/ZrO2 systems was studied by DRIFT spectroscopy. After reduction of Pt−Pd/ZrO2 at 100 °C, the states of the metals are mainly Pt0 and Pd0 with a minor admixture of positively charged forms of Pt+ or Pd2+. An increase in the temperature of reduction leads to the formation of a bimetallic alloy. In the Pt−Pd/SO4/ZrO2 system, the effects of alloy formation and the interaction of the surface SO4 groups superimpose. At low reduction temperatures, the surface SO4 groups interact mainly with palladium. The influence of the surface sites on both supported metals increases with increasing
reduction temperature.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1265–1270, July, 1999. 相似文献
8.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1981,37(10):923-924
Anionic halogenocadmate(II) complexes of the type CdCl3X2− have been prepared and characterized as salts of tetrapropylammonium. The Raman spectra of these crystalline solids have been interpreted in terms of a C3v symmetry. The tetrachlorocadmate(II) anion also possesses such a symmetry in the solid state. 相似文献
9.
钾芒硝是一种成因复杂的复盐[1~ 3 ] ,并且由于钾芒硝K3 Na(SO4 ) 2 与硫酸钾石 [K3 Na(SO4 ) 2 或Na2 SO4 ·3K2 SO4 ]的化学组成相同 ,未能确定二者是否属于同一种复盐[4 ,5] 。我们合成了复盐K3 Na(SO4 )2[3 ] ,用溶解量热法测定了K3 Na(SO4 )2 和反应物 [Na2 SO4 (s) +K2 SO4 (s) ]的溶解焓 ,通过设计热化学循环计算出复盐的标准生成焓 ,为我们了解钾芒硝和硫酸钾石是否为同一复盐 ,并为进一步研究其成因和组成提供参考。1 实验部分1 1 试剂与仪器K2 SO4 (s)和Na2 SO4 (s)为A .R .… 相似文献
10.
V. L. Lobachev 《Theoretical and Experimental Chemistry》1999,35(1):40-44
The substrate selectivity in the hydroxylation of methylbenzenes in the H2O2−H2SO4 (70 wt.%) system was studied at 15–55 °C. The activation entropy correlates with the basicity of the arenes, while the substrate
selectivity and activation enthalpy correspond both with the basicity and ionization potentials of ArH. We concluded that
the structure of the reaction transition state is intermediate between a charge transfer complex and σ-complex.
L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg
ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 35, No. 1, pp. 39–43, January–February,
1999. 相似文献
11.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(7):1309-1315
The ESR spectra of the kainite (KMgClSO4.3H2O) crystal revealed an intense isotropic (g = 2.004) peak C attributed to the SO−3 radical and two pairs of lines (A1, A2) and (B1, B2) bearing intensity ratio 5:3. The intensity and linewidth variation of peak C suggested that the signal contains an unresolved shf structure. The power saturation studies on SO−3 indicate that its ESR line is homogeneously broadened and its line shape is Lorentzian. The spin—lattice and spin—spin relaxation times (T1 and T2) of SO−3 have been estimated to be 0.44 s and 656 μs, respectively. The analysis of the anisotropic pairs of lines show that they constitute two sets A and B and are due to two chemically inequivalent SO−4 radical species in the lattice. The ESR spectra of the polycrystalline samples recorded at 300 and 77 K confirm the isotropic behaviour of SO−3 and chemical inequivalence of two types of SO−4 radicals. The principal g-values of the SO−4 radical were evaluated to be: g1 = 2.007, g2 = 2.011, g3 = 2.014 for species A and g1 = 2.008, g2 = 2.012, g3 = 2.015 for species B. The low microsymmetry of the SO2−4 ion in the lattice seems to promote the radiation damage. 相似文献
12.
《Solid State Sciences》2000,2(4):495-500
The polythermal diagram of the ternary system H2ONa2HPO4Na2SO4 has been established, setting up nine isotherms obtained between 0 and 25°C by conductimetric analysis. The solubility domains of the various solid phases have been determined. One eutectic, three stable and one metastable transitional transformations have been observed. Temperature and composition of the eutectic point have been obtained by thermal analysis at constant flow. 相似文献
13.
L. Soliev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(9):1442-1447
Phase equilibria of the Na,K,Mg,Na,K,Mg,Ca//SO4,Cl-H2O system are studied at 50°C via translation in the crystallization range of glaserite (3K2SO4 · Na2SO4). It is found that glaserite as the equilibrium phase of the investigated system at 50°C participates in the formation of 21 invariant points, 21 monovariant curves, and 34 divariant fields. A fragment of the phase equilibria diagram of the investigated system is constructed in the crystallization range of glaserite. 相似文献
14.
15.
《Journal of solid state chemistry》1987,69(2):289-298
We have synthesized several compounds of the ZnxCd1−xIn2S4 family by solid phase reactions and chemical transport reactions using iodine. The reaction products have been characterized as to composition, structure, and lattice dynamics. Here we discuss and compare the different results obtained by the two synthesis methods. 相似文献
16.
L. K. Volkova V. L. Lobachev E. S. Rudakov 《Theoretical and Experimental Chemistry》1999,35(6):325-329
The kinetics, kinetic isotope effects, and substrate selectivity were studied for the oxidation of alkylbenzenes in the HVO3−H2SO4 system at 30°C. The reaction proceeds by an electrophilic substitution mechanism through a slow step involving formation
of a charge transfer complex between the arene and VO
2
+
cation and is similar to nitration by the NO
2
+
cation.
L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg
ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 6, pp. 349–353, November–December,
1999. 相似文献
17.
F. El-Kabbany F. M. Mansey H. Naguib A. Al-Huwari 《Journal of Thermal Analysis and Calorimetry》1997,48(2):287-295
The effect of partial replacement of K+ by Ag+ in the mixed system of KNO3 and AgNO3 during a set of DSC heating cycles was studied by means of a modern computerized DSC system. Thermal analysis was performed in the vicinity of the phase transition II I for pure KNO3. The results revealed a large change in enthalpy and the phase transition temperature close to the morphotropic boundary x=0.5–0.6. At this boundary, the transformation enthalpy reached the maximum value of 101 J g–1. On the basis of the data obtained from this accurate thermal analysis work, a model is suggested for the energy barrier of rotation of the nitrate ion in the mixed nitrate system. 相似文献
18.
E. Radomińska T. Znamierowska W. Szuszkiewicz 《Journal of Thermal Analysis and Calorimetry》2011,103(2):761-766
The system Rb3PO4–Ba3(PO4)2 was investigated by thermoanalytical methods, X-ray powder diffraction, ICP, and FT-IR. On the basis of the obtained results
its phase diagram was proposed. For this system with one intermediate compound, BaRbPO4, we found that this compound melts congruently at 1700 °C, exhibits a polymorphic transition at 1195 °C and is high-temperature
unstable. Also, the intermediate compound was subject to gradual decomposes to Ba3(PO4)2 (the solid phase) and vaporization (with conversion of phosphorus and rubidium oxides into vapor phase). We also found that
Rb3PO4 melts congruently at 1450 °C and shows a polymorphic transition at 1040 °C. Regarding Ba3(PO4)2, we have confirmed that it melts congruently at 1605 °C and exhibits a polymorphic transition at 1360 °C. 相似文献
19.
For the equilibrium solid phases occurring in the systems: KCl?KBr?H2O, K2SO4?(NH4)2SO4?H2O and KNO3?NH4NO3?H2O, the concentration dependencies of differential solution enthalpies, Δsol H 2 for several crystallization paths, were measured. The limiting differential solution enthalpies, Δsol H 2 0 , were determined by extrapolation of the above dependencies to the ionic strength,I m 0 , corresponding to the appropriate binary solutions. For KCl?KBr?H2O system only, the clear dependence between Δsol H 2 0 andI m 0 values was found and discussed. 相似文献
20.
A. Tomasi P. Scardi F. C. Matacotta P. Nozar 《Journal of Thermal Analysis and Calorimetry》1996,47(1):27-34
Carbocuprate compounds are generally described as multiple perovskites with CO
3
2
- and Cu-O alternating layers containing Ba and/or Sr; they have gained an unexpected importance in the high temperature superconductivity field, because many compounds with transition temperature above 100 K belong to this class of materials.We have started a systematic study on phase formation and stabilisation in the Ba-Cu-C-O system in the temperature range 20-600°C, by using thermal analysis techniques. Starting from a BaCO3-BaO2-CuO mixture (311 mol), a new phase isomorphic with BaCO3 formed after heat treatment above 390°C in air. TG, DSC, EGA and high temperature XRD were employed to follow the complex interaction of the reactants with the atmosphere and the formation of the new phase. 相似文献