The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy po...The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy powders after gaseous hydriding and dehydriding cycle was investigated and the discovery was that annealing treatment could hardly ameliorate their anti-pulverization ability. The element content of La, Mg, Ni and Co existing in electrolyte before and after the electrochemical cycles by using ICP-AES technology was also analyzed and it showed that a large amount of La and Mg were dissolved in the electrolyte, but the amount of dissolution for La and Mg significantly declined when the alloy was annealed. The XRD analysis revealed that all the al- loys consisted of two main phases AB3 and AB2 and a residual phase AB5 while annealing treatment made the AB2 phase decrease slightly. Furthermore, the anti-corrosion abilities of various elements in different phases of the as-cast and annealed alloy samples were studied by analyzing the element （La, Mg, Ni, Co） change with the corrosion time in phases AB3 and AB2 by means of EDS. It turned out that the element of La was mainly corroded out from the phase AB2 while not easily from the phase AB3. However, the element of Mg was both easily corroded out from the phases AB2 and AB3, but the corrosion was more obvious in the phase AB3. Therefore, annealing improved the anti-corrosion performances of La and Mg in the phase AB2.展开更多
Relaxor-type ferroelectric perovskites attract a lot of attentions due to their excellent dielectric and electrostrictive properties. (Ba,La)(Mg, Nb)O3(BLMN) ceramics were synthesized from oxides by sintering in airs ...Relaxor-type ferroelectric perovskites attract a lot of attentions due to their excellent dielectric and electrostrictive properties. (Ba,La)(Mg, Nb)O3(BLMN) ceramics were synthesized from oxides by sintering in airs using a conventional mixed oxide process. Thermogravimetry-differential analyzer (TG-DTA) analysis shows that the fired temperature of the Ba(Mg1/3, Nb2/3)O3 is above 1627.2 K. From the study of X-ray diffraction (XRD) patterns, it is founded that the amount of the perovskite phase increases with the increasing amount of La2O3. Furthermore, by the X-ray photoelectron spectroscopy (XPS) analysis, it is discovered that the amount of Nb4+ is increased as La2O3 dopant increases from 0 to 0.04.展开更多
La0.75Mg0.25Ni3.5–xCo0.2Alx （x=0–0.09） hydrogen storage alloys were prepared by induction melting and effect of Al substitution for Ni on phase constitution and electrochemical property was investigated.With the s...La0.75Mg0.25Ni3.5–xCo0.2Alx （x=0–0.09） hydrogen storage alloys were prepared by induction melting and effect of Al substitution for Ni on phase constitution and electrochemical property was investigated.With the substitution of Al for Ni,LaNi5 and LaNi2 phases occurred and （La,Mg）2（Ni,Co,Al）7 phase with hexagonal Ce2Ni7-type structure replaced （La,Mg）2（Ni,Co）7 phase.The cell volumes of LaNi5 and （La,Mg）2（Ni,Co,Al）7 main phases increased with increasing Al content.Some electrochemical properties and kinetic parameters of the alloys,including discharge capacity,high rate discharge ability （HRD）,loss angle （ψ）,exchange current density （I0） and limiting current density （IL）,decreased with increasing amount of substitution of Al for Ni.Substitution of Al for Ni could be favorable for positive shift in corrosion potential of the alloy electrode,and prolonged cyclic lifetime of La0.75Mg0.25Ni3.5–xCo0.2Alx （x=0–0.09） alloy electrodes.展开更多
La-Mg-Ni alloys were prepared by melt-spinning with different cooling rates and followed by annealing.Elevation of the cooling rate leads to refinement of the grains size and increasing of the abundance of LaNis.Annea...La-Mg-Ni alloys were prepared by melt-spinning with different cooling rates and followed by annealing.Elevation of the cooling rate leads to refinement of the grains size and increasing of the abundance of LaNis.Annealing is favorable to formation of the A2 B7-type phase and promotes the discharge capacity,cycling stability and high rate discharge ability of the as-spun alloys.Phase constitution of the annealed alloys is found to be closely related to the microstructure of the as-spun alloys.A single phase A2 B7-type microstructure is obtained in the annealed alloy which is attributed to the lower abundance of the LaNis of the original alloy spun with lower cooling rate.Formation of the single phase A2 B7-type microstructure is also ascribed to the isolated and homogeneous distribution of the morphology of the as-spun alloy.The single phase alloy presents higher discharge capacity and better cycling stability compared with other annealed alloys.展开更多
To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of di...To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of different annealed alloys were investigated systematically by X-Ray Diffraction （XRD）, Scanning Electron Microscopy （SEM）, X-Ray Photoelectron Spectroscopy （XPS）, and electrochemical experiments. The results obtained by XRD and SEM showed that the as-cast and annealed （1123 K） alloys had multiphase structure containing LaNis, （La, Mg）2（Ni, Co）7 and few LaNi2 phases. When annealing temperatures approached 1223 and 1323 K, LaNi2 phase disappeared. The annealed alloys at 1223 and 1323 K were composed of LaNi5, （La, Mg）2（Ni, Co）7 and （La, Mg）（Ni, Co）3 phases. With increasing annealing temperature, the maximum discharge capacity of the alloy decreased monotonously, but the cyclic stability was improved owing to structure homogeneity and grain growth after annealing, as well as the enhancement of anti-oxidation/corrosion ability and the suppression of pulverization during cycling in KOH electrolyte.展开更多
基金Project supported by the National Key Laboratory of New Metal(Z2011-11)the National Natural Science Foundation of China(51471054)
文摘The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy powders after gaseous hydriding and dehydriding cycle was investigated and the discovery was that annealing treatment could hardly ameliorate their anti-pulverization ability. The element content of La, Mg, Ni and Co existing in electrolyte before and after the electrochemical cycles by using ICP-AES technology was also analyzed and it showed that a large amount of La and Mg were dissolved in the electrolyte, but the amount of dissolution for La and Mg significantly declined when the alloy was annealed. The XRD analysis revealed that all the al- loys consisted of two main phases AB3 and AB2 and a residual phase AB5 while annealing treatment made the AB2 phase decrease slightly. Furthermore, the anti-corrosion abilities of various elements in different phases of the as-cast and annealed alloy samples were studied by analyzing the element （La, Mg, Ni, Co） change with the corrosion time in phases AB3 and AB2 by means of EDS. It turned out that the element of La was mainly corroded out from the phase AB2 while not easily from the phase AB3. However, the element of Mg was both easily corroded out from the phases AB2 and AB3, but the corrosion was more obvious in the phase AB3. Therefore, annealing improved the anti-corrosion performances of La and Mg in the phase AB2.
文摘Relaxor-type ferroelectric perovskites attract a lot of attentions due to their excellent dielectric and electrostrictive properties. (Ba,La)(Mg, Nb)O3(BLMN) ceramics were synthesized from oxides by sintering in airs using a conventional mixed oxide process. Thermogravimetry-differential analyzer (TG-DTA) analysis shows that the fired temperature of the Ba(Mg1/3, Nb2/3)O3 is above 1627.2 K. From the study of X-ray diffraction (XRD) patterns, it is founded that the amount of the perovskite phase increases with the increasing amount of La2O3. Furthermore, by the X-ray photoelectron spectroscopy (XPS) analysis, it is discovered that the amount of Nb4+ is increased as La2O3 dopant increases from 0 to 0.04.
基金Project supported by National 863 Program of China (2007AA03Z227, 2007AA03Z230)Natural Science Foundation of Hebei Province (E2010000301)+1 种基金Natural Science Research Planned Project of Hebei University (2009-152)Undergraduate Science and Technology Innovation Project of Hebei University (2010060)
文摘La0.75Mg0.25Ni3.5–xCo0.2Alx （x=0–0.09） hydrogen storage alloys were prepared by induction melting and effect of Al substitution for Ni on phase constitution and electrochemical property was investigated.With the substitution of Al for Ni,LaNi5 and LaNi2 phases occurred and （La,Mg）2（Ni,Co,Al）7 phase with hexagonal Ce2Ni7-type structure replaced （La,Mg）2（Ni,Co）7 phase.The cell volumes of LaNi5 and （La,Mg）2（Ni,Co,Al）7 main phases increased with increasing Al content.Some electrochemical properties and kinetic parameters of the alloys,including discharge capacity,high rate discharge ability （HRD）,loss angle （ψ）,exchange current density （I0） and limiting current density （IL）,decreased with increasing amount of substitution of Al for Ni.Substitution of Al for Ni could be favorable for positive shift in corrosion potential of the alloy electrode,and prolonged cyclic lifetime of La0.75Mg0.25Ni3.5–xCo0.2Alx （x=0–0.09） alloy electrodes.
基金Project supported by the National Natural Science Foundation of China(51761032,51501095)the University Foundation of Inner Mongolia(NJZZ18142)Natural Science Foundation of Inner Mongolia(2018MS05040)
文摘La-Mg-Ni alloys were prepared by melt-spinning with different cooling rates and followed by annealing.Elevation of the cooling rate leads to refinement of the grains size and increasing of the abundance of LaNis.Annealing is favorable to formation of the A2 B7-type phase and promotes the discharge capacity,cycling stability and high rate discharge ability of the as-spun alloys.Phase constitution of the annealed alloys is found to be closely related to the microstructure of the as-spun alloys.A single phase A2 B7-type microstructure is obtained in the annealed alloy which is attributed to the lower abundance of the LaNis of the original alloy spun with lower cooling rate.Formation of the single phase A2 B7-type microstructure is also ascribed to the isolated and homogeneous distribution of the morphology of the as-spun alloy.The single phase alloy presents higher discharge capacity and better cycling stability compared with other annealed alloys.
基金Project supported by the National Natural Science Foundation of China(50642033 50701011)+1 种基金Key Technologies R&D Program of Inner Mongolia, China (20050205)Natural Science Foundation of Inner Mongolia, China (200711020703)
文摘To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of different annealed alloys were investigated systematically by X-Ray Diffraction （XRD）, Scanning Electron Microscopy （SEM）, X-Ray Photoelectron Spectroscopy （XPS）, and electrochemical experiments. The results obtained by XRD and SEM showed that the as-cast and annealed （1123 K） alloys had multiphase structure containing LaNis, （La, Mg）2（Ni, Co）7 and few LaNi2 phases. When annealing temperatures approached 1223 and 1323 K, LaNi2 phase disappeared. The annealed alloys at 1223 and 1323 K were composed of LaNi5, （La, Mg）2（Ni, Co）7 and （La, Mg）（Ni, Co）3 phases. With increasing annealing temperature, the maximum discharge capacity of the alloy decreased monotonously, but the cyclic stability was improved owing to structure homogeneity and grain growth after annealing, as well as the enhancement of anti-oxidation/corrosion ability and the suppression of pulverization during cycling in KOH electrolyte.
