The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
H. Näfe - One of the best experts on this subject based on the ideXlab platform.
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voltage of a solid electrolyte Galvanic Cell in terms of the activity of the mobile species of the electrolyte
Electrochimica Acta, 2007Co-Authors: H. NäfeAbstract:The voltage of a solid electrolyte Galvanic Cell is not related to the activity of the mobile ions in the electrolyte which is why this activity is not a measurable quantity. Any different view contradicts fundamental relationships inherent in solid state electrochemistry.
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characterization of the conduction properties of a solid electrolyte by short circuiting a potentiometric Galvanic Cell
Journal of Solid State Electrochemistry, 2005Co-Authors: H. NäfeAbstract:By short-circuiting a solid electrolyte Galvanic Cell, the ionic conductivity of the electrolyte employed in the Cell can be determined. There is no other potential involved in this technique with regard to the characterization of the conduction properties of the electrolyte. In particular, the method does not offer any information about the electronic conductivity.
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Solid electrolyte Galvanic Cell under load
Journal of Applied Electrochemistry, 2001Co-Authors: H. NäfeAbstract:Relationships are derived which describe the voltage of and the ionic and electronic currents through a solid electrolyte Galvanic Cell under load as an explicit function of the independent variables. These relationships result from an appropriate extension of the classical Wagner approach for the open circuit case to the conditions of a Cell in charge or discharge mode. The formulae represent generalized versions of the Wagner-Schmalzried equations. They readily allow determination of the chemical potential distribution throughout the electrolyte under load conditions.
V Venugopal - One of the best experts on this subject based on the ideXlab platform.
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synergistic use of knudsen effusion quadrupole mass spectrometry solid state Galvanic Cell and differential scanning calorimetry for thermodynamic studies on lithium aluminates
Journal of Solid State Chemistry, 2008Co-Authors: S K Rakshit, Y P Naik, S C Parida, Smruti Dash, Ziley Singh, V VenugopalAbstract:Abstract Three ternary oxides LiAl 5 O 8 (s), LiAlO 2 (s) and Li 5 AlO 4 (s) in the system Li–Al–O were prepared by solid-state reaction route and characterized by X-ray powder diffraction method. Equilibrium partial pressure of CO 2 (g) over the three-phase mixtures {LiAl 5 O 8 (s)+Li 2 CO 3 (s)+5Al 2 O 3 (s)}, {LiAl 5 O 8 (s)+5LiAlO 2 (s)+2Li 2 CO 3 (s)} and {LiAlO 2 (s)+Li 5 AlO 4 (s)+2Li 2 CO 3 (s)} were measured using Knudsen effusion quadrupole mass spectrometry (KEQMS). Solid-state Galvanic Cell technique based on calcium fluoride electrolyte was used to determine the standard molar Gibbs energies of formations of these aluminates. The standard molar Gibbs energies of formation of these three aluminates calculated from KEQMS and Galvanic Cell measurements were in good agreement. Heat capacities of individual ternary oxides were measured from 127 to 868 K using differential scanning calorimetry. Thermodynamic tables representing the values of Δ f H 0 (298.15 K), S 0 (298.15 K) S 0 ( T ), C p 0 ( T ), H 0 ( T ), { H 0 ( T )– H 0 (298.15 K)}, G 0 ( T ), Δ f H 0 ( T ), Δ f G 0 ( T ) and free energy function (fef) were constructed using second law analysis and FACTSAGE thermo-chemical database software.
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standard molar gibbs energies of formation of the ternary compounds in the la co o system using solid oxide Galvanic Cell method
Journal of Alloys and Compounds, 1999Co-Authors: S C Parida, Smruti Dash, Ziley Singh, R Prasad, V VenugopalAbstract:Abstract The standard molar Gibbs energies of formation of the ternary oxide compounds; LaCoO 3 (s), La 4 Co 3 O 10 (s) and La 2 CoO 4 (s) in the La-Co-O system have been determined by a solid oxide Galvanic Cell method using 15 mole% calcia stabilized zirconia as the solid electrolyte. The corresponding expressions for the Δ f G m °(T) are given as: Δ f G m °(LaCoO 3 , s, T) (kJ mol −1 ) (±0.6)=−1234.2+0.272T ( K ) (1002 K ≤T≤1204 K ), Δ f G m °(La 4 Co 3 O 10 , s, T) (kJ mol −1 ) (±3.2)=−4663.8+0.969T (K) (1009 K≤T≤1238 K) and Δ f G m °(La 2 CoO 4 , s, T) (kJ mol −1 )(±1.1)=−2017.1+0.347T (K) (1004 K≤T≤1171 K).
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molar gibbs free energy of formation of rb2u4o11 s by solid oxide electrolyte Galvanic Cell
Journal of Alloys and Compounds, 1996Co-Authors: V S Iyer, K Jayanthi, S K Sali, S Sampath, V VenugopalAbstract:Abstract The molar Gibbs' free energy of formation of Rb 2 U 4 O 11 was determined by measuring the oxygen potentials over the Rb 2 U 4 O 11 + Rb 2 U 4 O 12 system using a solid oxide electrolyte Galvanic Cell with Ni + NiO as reference electrode in the temperature range 985–1186 K. It was found by X-ray diffraction analysis that Rb 2 U 4 O 11 coexists with Rb 2 U 4 O 12 up to 1300 K. The molar Gibbs' free energy formation of Rb 2 U 4 O 11 is calculated from the e.m.f. values and can be given by: Δ f G ° (kJ mol −1 ) ± 0.65 = −5348.87 + 1.076 T (K). The kinetics of oxidation of Rb 2 U 4 O 11 in air, studied by thermogravimetry indicated that the reaction is phase boundary controlled with an activation energy of 123.6 kJ mol −1 .
Jian Bi - One of the best experts on this subject based on the ideXlab platform.
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oxidant assisted preparation of camoo4 thin film using an irreversible Galvanic Cell method
Thin Solid Films, 2010Co-Authors: Ping Cheng, Jian BiAbstract:Abstract CaMoO4 thin films were prepared by an irreversible Galvanic Cell method at room temperature; the crystalline phase structure, surface morphology, chemical composition and room temperature photoluminescence property were characterized by X-ray diffraction, Raman spectroscopy, scanning electronic microscopy, X-ray photoelectron spectroscopy as well as photoluminescence spectroscopy. Our results reveal that it is very difficult to directly deposit dense and uniform CaMoO4 thin films in saturated Ca(OH)2 solution at room temperature by the irreversible Galvanic Cell method. After adding some oxidant (NaClO solution or H2O2 solution), the growth of CaMoO4 grains has been promoted, and well-crystallized, dense, and uniform CaMoO4 films were obtained. The as-prepared CaMoO4 films exhibit a good green photoluminescence, with the excitation of various wavelengths (220 nm, 230 nm, 240 nm, 250 nm and 270 nm) of ultraviolet irradiation.
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Analysis of Galvanic Cell deposition process in preparation of BaMoO4 films
Journal of Materials Science, 2009Co-Authors: Chunyan Wu, Bo Li, Jian BiAbstract:The Galvanic Cell method has been used for the synthesis of BaMoO4 double oxide film in barium hydroxide aqueous solutions. This method could resolve the repulsion of the electric field on the anode and favor the mass transfer of cations. The crystal growth in the solution is easier compared with the traditional electrochemical deposition with applied power. The deposition process of the Galvanic Cell technique has been investigated by deposition time, pH, and ion concentration, and the basic features of this method are discussed.
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Room temperature synthesis of crystallized luminescent SrWO4 films by an adjustable Galvanic Cell method
Journal of Crystal Growth, 2008Co-Authors: Jian BiAbstract:Abstract Highly crystallized luminescent SrWO 4 films were prepared directly on tungsten substrate in strontium hydroxide aqueous solution by a Galvanic Cell method without impressed current at room temperature. It is noteworthy that the driving force of Galvanic Cell method is adjustable by adding different concentrations of oxidant. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results reveal that the crystallized films have a scheelite-type tetragonal structure and homogeneous surface. The film showed single blue emissions at 447 nm with excitation lights of 220, 230, 250, 260 and 270 nm at room temperature, respectively.
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morphology and crystal phase control in preparation of highly crystallized bawo4 film via Galvanic Cell method
Journal of Alloys and Compounds, 2008Co-Authors: Jian Bi, Keqing ZhaoAbstract:Abstract Highly crystallized BaWO 4 films have been prepared by a Galvanic Cell method without impressed current on tungsten substrates at room temperature. The surface morphology, grain size and crystal phase of BaWO 4 films have been controlled effectively by adjusting ion-concentration, pH and even adding adequate surfactant. The BaWO 4 films are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD). The results indicate that the films have single phase and uniform surfaces. The grain size was changed under different treatment conditions.
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room temperature preparation of highly crystallized cawo4 film by a Galvanic Cell method
Materials Letters, 2008Co-Authors: Jian BiAbstract:Abstract Highly crystallized CaWO 4 film has been prepared directly by a Galvanic Cell method on tungsten substrates in calcium hydroxide aqueous solution without impressed current at room temperature (25 °C). The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results reveal that the crystallized film has a scheelite-type tetragonal structure, uniform and homogeneous surface. The film shows only the blue emission of 447.5 nm with the excitation light of 250 nm at room temperature. The formation mechanism of CaWO 4 film under the simple electrochemical process has been discussed. This method could resolve the repulsion of the electric field on the anode for the mass transfer. The crystal growth in the solution is freer.
Seshadri Seetharaman - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic investigation of the Co-Cr system by the solid state Galvanic Cell technique involving CaF2 solid electrolyte
2020Co-Authors: Therese Sterneland, Ragnhild Aune, Seshadri SeetharamanAbstract:Thermodynamic investigation of the Co-Cr system by the solid state Galvanic Cell technique involving CaF2 solid electrolyte
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Thermodynamic Investigation of Co-Cr Alloys, I. Galvanic Cell Measurements of Chromium Activities in the Temperature Interval 1026-1297 K
2020Co-Authors: Therese Sterneland, Ragnhild Aune, Seshadri SeetharamanAbstract:Thermodynamic Investigation of Co-Cr Alloys, I. Galvanic Cell Measurements of Chromium Activities in the Temperature Interval 1026-1297 K
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Thermodynamic investigations of the Mn-Ni-C-N quarternary alloys by solid-state Galvanic Cell technique
Journal of Alloys and Compounds, 2005Co-Authors: Lidong Teng, Ragnhild Aune, Seshadri SeetharamanAbstract:In view of the important applications of carbides and nitrides of transition metals in the hard materials industries, the thermodynamic activities of manganese in Mn-Ni-C-N alloys have been studied by solid-state Galvanic Cell technique with CaF 2 as the solid electrolyte. The phase compositions and microstructure of various alloys have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Nitrogen was introduced into the alloy by equilibrating with N 2 gas. It was established during the experiments that the solubility of nitrogen in the alloys was affected by the carbon content. A (Mn,Ni) 4(N,C) nitride was formed during the nitriding procedure in the alloys. The electromotive force (EMF) measurements were carried out in the temperature range 940-1127 K in order to determine the activities of Mn in the alloys. The activities of manganese were calculated and compared with those of the corresponding Mn-Ni-C ternary alloys. © 2004 Elsevier B.V. All rights reserved.
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thermodynamic studies of some fe pt alloys by the solid electrolyte Galvanic Cell method
Scandinavian Journal of Metallurgy, 2001Co-Authors: Patrik Fredriksson, Seshadri SeetharamanAbstract:In the present investigation, the thermodynamic activities of iron in iron-platinum solid alloys were measured by the solid electrolyte Galvanic Cell method in the temperature range 1073–1273 K. The Galvanic Cell employed can be represented as (−) Pt, Fe(s), FetO(s) // ZrO2(11 mol pct CaO) // FetO(s), Fe-Pt alloys, Pt(+) The experimental set-up as well as the satisfactory performance of the Galvanic Cell were validated by measuring the standard Gibbs energy of formation of CoO in equilibrium with Co in the same temperature range by replacing the working electrode by a Co, CoO mixture. 6 different Fe-Pt alloys covering the entire composition range were studied and the results are compared with earlier thermodynamic studies available in the literature. The present experimental results are found to be in general agreement with those of Alcock and Kubik. The values were fitted into a regular solution description in order to estimate the enthalpies of mixing Pt and Fe in the solid alloys.
Pekka Taskinen - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic properties of ag3ause2 from 300 to 500 k by a solid state Galvanic Cell
Journal of Alloys and Compounds, 2014Co-Authors: Dawei Feng, Pekka TaskinenAbstract:Abstract The numerical values of the standard thermodynamic functions of Ag 3 AuSe 2 (fischesserite) in the Ag–Au–Se system were determined by the electromotive force (EMF) method in a solid state Galvanic Cell with RbAg 4 I 5 as the solid electrolyte below 500 K. Ag 3 AuSe 2 was synthesized from pure elements in stoichiometric composition by evacuated ampoules made of quartz glass. On the basis of EMF vs. temperature experimental data, the analytical equations were obtained, from which the temperature dependent relationships of the Gibbs energy in the relevant reactions and the standard thermodynamic functions of Ag 3 AuSe 2 within the temperature range of 300–500 K were calculated. The results show that there is possible a new polymorphic transformation around 350 K.
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thermodynamic stability of ag2se from 350 to 500 k by a solid state Galvanic Cell
Solid State Ionics, 2013Co-Authors: Dawei Feng, Pekka Taskinen, Fiseha TesfayeAbstract:Abstract The numerical values on the standard thermodynamic functions of Ag 2 Se (naumannite) were determined by the electromotive force (EMF) method in a solid-state Galvanic Cell with superionic conductor RbAg 4 I 5 as the solid electrolyte. Ag 2 Se was synthesized from pure elements in evacuated quartz glass ampoules and examined to be homogenous by SEM and EDS. According to the experimental data on the EMF versus temperature, the analytical equations were obtained for the polymorphic forms of Ag 2 Se. The temperature-dependent relationships of the Gibbs energy of formation of Ag 2 Se in its polymorphic forms and the standard thermodynamic functions of compounds within the temperature range of 350–500 K were also evaluated. The temperature of phase transformation from α-Ag 2 Se to β-Ag 2 Se is determined experimentally to be 407.7 K and the enthalpy of phase transformation is 6.06 kJ mol − 1 .
