The electrochemical formation processes of holmium-cobalt alloys on cobaltcathode in molten HoCl_3-KCl were investigated by cyclic voltammetry and open current potential-timecurve alter potentiostatic electrolysis. Th...The electrochemical formation processes of holmium-cobalt alloys on cobaltcathode in molten HoCl_3-KCl were investigated by cyclic voltammetry and open current potential-timecurve alter potentiostatic electrolysis. The structure of Ho-Co alloys' films deposited on cobaltelectrode by potentiostatic electrolysis was characterized by X-ray diffraction. The standard Gibbsfree energies of formation for the intermetallic compounds of Ho and Co were determined. Thediffusion coefficient and diffusion activation energy of Ho atom in the alloy phase were calculatedto be 10^(-10) -10^(-11) cm^2/s and 96.0 kJ/mol, respectively, from the current-time curve atpotential step.展开更多
The nano powders of LaCrO3 were prepared by a sol-gel route. The heat capacity of LaCrO3 nano powders from 350 to 550 K was measured by DSC method and expressed as： Cpa2CrO3） （±0.112） = 166.844 - 8.500 ×...The nano powders of LaCrO3 were prepared by a sol-gel route. The heat capacity of LaCrO3 nano powders from 350 to 550 K was measured by DSC method and expressed as： Cpa2CrO3） （±0.112） = 166.844 - 8.500 ×10^-3T- 1.022×10^6T^-2 （J/（mol.K）） （350-550 K）. An EMF measurement assembly was developed with CaF2 as an electrolyte for the galvanic cell. From measured EMF data of the reversible cell, （-） PL La2O3, LaF3, O2 （1 atm）lCaF2O2（1 atm）, LaF3, LaCrO3, Cr2O3, Pt（＋）, and the relevant value of Gibbs free energy, the Gibbs free energy of formation of LaCrO3 was calculated from 700 to 885 K： △G ФaLaCrO3 = -1555.364 ＋ 0.354T （kJ/mol） （700-885 K）. And the Gibbs free energy change of reaction from simple oxides La2O3 and Cr2O3 was calculated to be： AG f Oox（LaCrO3） = -94.758 ＋ 8.530×10^-2T（kJ/mol） （700-885 K）.展开更多
The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells： one using MgZr4（PO4）6 （MZP） as the solid electrolyte and the other using...The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells： one using MgZr4（PO4）6 （MZP） as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively： AG1 = -3579-15 T （J/mol） and AGⅡ =6258-24.3 T （J/mol）. The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao＇ s and Tretjakov＇s data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe203 were substituted in the reaction, the Gibbs free energies of formation of MgFe204 was obtained in two temperature ranges and the for mations are shown as follows： AG 1Formation =-1427394＋360.5 T （J/mol） and AGⅡ Formition =-1417557＋351.2 T （J/mol）.展开更多
The compounds of RESF. RE = La. Ce. Pr, Y and Tb, were made from RE_2S_3 and REF_3 by high tem-perature solid reaction. The Gibbs standard free energies of formation of RESF were measured by galvaniccell technique by ...The compounds of RESF. RE = La. Ce. Pr, Y and Tb, were made from RE_2S_3 and REF_3 by high tem-perature solid reaction. The Gibbs standard free energies of formation of RESF were measured by galvaniccell technique by using CSZ as solid electrolyte. The results of this work together with the Gibbs standardfree energies of formation ol RE,S. . REzSa and REFa were used to determine the phase diagrams ofRESF systems in this paper.展开更多
文摘The electrochemical formation processes of holmium-cobalt alloys on cobaltcathode in molten HoCl_3-KCl were investigated by cyclic voltammetry and open current potential-timecurve alter potentiostatic electrolysis. The structure of Ho-Co alloys' films deposited on cobaltelectrode by potentiostatic electrolysis was characterized by X-ray diffraction. The standard Gibbsfree energies of formation for the intermetallic compounds of Ho and Co were determined. Thediffusion coefficient and diffusion activation energy of Ho atom in the alloy phase were calculatedto be 10^(-10) -10^(-11) cm^2/s and 96.0 kJ/mol, respectively, from the current-time curve atpotential step.
基金This project is financially supported by the National Natural Science Foundation of China (Nos. 50374009, 20331030, and 20571009)
文摘The nano powders of LaCrO3 were prepared by a sol-gel route. The heat capacity of LaCrO3 nano powders from 350 to 550 K was measured by DSC method and expressed as： Cpa2CrO3） （±0.112） = 166.844 - 8.500 ×10^-3T- 1.022×10^6T^-2 （J/（mol.K）） （350-550 K）. An EMF measurement assembly was developed with CaF2 as an electrolyte for the galvanic cell. From measured EMF data of the reversible cell, （-） PL La2O3, LaF3, O2 （1 atm）lCaF2O2（1 atm）, LaF3, LaCrO3, Cr2O3, Pt（＋）, and the relevant value of Gibbs free energy, the Gibbs free energy of formation of LaCrO3 was calculated from 700 to 885 K： △G ФaLaCrO3 = -1555.364 ＋ 0.354T （kJ/mol） （700-885 K）. And the Gibbs free energy change of reaction from simple oxides La2O3 and Cr2O3 was calculated to be： AG f Oox（LaCrO3） = -94.758 ＋ 8.530×10^-2T（kJ/mol） （700-885 K）.
基金the National Natural Science Foundation of China (No.50572024) the Education Ministry Foundation for Returning Overseas Scholar of China.
文摘The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells： one using MgZr4（PO4）6 （MZP） as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively： AG1 = -3579-15 T （J/mol） and AGⅡ =6258-24.3 T （J/mol）. The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao＇ s and Tretjakov＇s data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe203 were substituted in the reaction, the Gibbs free energies of formation of MgFe204 was obtained in two temperature ranges and the for mations are shown as follows： AG 1Formation =-1427394＋360.5 T （J/mol） and AGⅡ Formition =-1417557＋351.2 T （J/mol）.
文摘The compounds of RESF. RE = La. Ce. Pr, Y and Tb, were made from RE_2S_3 and REF_3 by high tem-perature solid reaction. The Gibbs standard free energies of formation of RESF were measured by galvaniccell technique by using CSZ as solid electrolyte. The results of this work together with the Gibbs standardfree energies of formation ol RE,S. . REzSa and REFa were used to determine the phase diagrams ofRESF systems in this paper.
