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Electrochemical formation of holmium-cobalt alloys

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Rare Metals 2003年第1期22卷 19-24页

作者： SUYuzhi YANGQiqin LIUGuankun DepartmentofChemistry SchoolofBiologicalandChemicalEngineeringGuangzhouUniversityGuangzhou510405China DepartmentofChemistry SchoolofChemistryandChemicalEngineeringZhongshanUniversityGuangzhou5102

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.

关键词： rare earths holmium-cobalt alloy electrochemical formation moltenchloride gibbs free energy of formation diffusion coefficient

Thermodynamic properties of LaCrO_3

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Rare Metals 2006年第5期25卷 562-566页

作者： CHEN Zhanheng XING Xianran YUAN Wenxia HUANG Xiaowei LI Hongwei School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Office of the Chinese Society of Rare Earths Beijing 100081 China National Engineering Research Center for Rare Earth Materials Beijing 100088 China

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）.

关键词： lanthanum chromate gibbs free energy of formation heat capacity EMF measurement nano powder

Calculation and Verification for the Thermodynamic Data of 3CaO·3Al_2O_3·CaSO_4

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Chinese Journal of Chemical Engineering 2011年第3期19卷 489-495页

作者：王文龙陈晓冬陈莹董勇马春元 National Engineering Laboratory for Coal-fired Pollutants Emission Reduction Shandong University

Calcium sulfoaluminate,3CaO·3Al2O3·CaSO4,has been widely recognized in the realms of high-temperature combustion and cement ***,the lack of relevant thermodynamic data limits the progress of its research and *** comparative calculations using several different approaches,we obtain the thermochemical properties of 3CaO·3Al2O3·CaSO4 in this work,such as its standard formation enthalpy,gibbs free en- ergy of formation,entropy,and molar heat *** these fundamental data,thermodynamic calculations become possible for reactions involving this *** is found that some reactions proposed in literature to generate this mineral may not proceed thermodynamically.

关键词： calcium sulfoaluminate standard formation enthalpy gibbs free energy of formation entropy molar heat capacity