A new approach of ball-milled Mg_2Ni in tetrahydrofuran (THF) to improve thehydriding kinetics of Mg_2Ni alloy is suggested and studied. It is found that the modified alloydisplayed the improved activity for hydriding...A new approach of ball-milled Mg_2Ni in tetrahydrofuran (THF) to improve thehydriding kinetics of Mg_2Ni alloy is suggested and studied. It is found that the modified alloydisplayed the improved activity for hydriding even at relatively low temperature (e.g., 323-373 K).In the case of the sample milled in THF for 20 h, the hydrogen content (mass fraction) reaches 1.6 %at 323 K, 2.1% at 348 K and 3.4% at 448 K, respectively. The use of THF during grinding led to thechange of the structure, which is reflected by the broadening and weakening of the diffraction peaksin the XRD spectra. The XPS analysis shows that Mg (2s) binding energy peak of Mg_2Ni aftermodification shifted from a lower binding energy to a higher one, indicating the charge transferencebetween Mg and THF and the formation of catalytically active electron donor-acceptor (EDA)complexes on the surface of modified Mg_2Ni alloy.展开更多
A series of Mg_(2-x)Nd_xNi (x=0.05, 0.1, 0.2, 0.3) alloys and Mg_(1.95)RE_(0.05)Ni (RE= La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixted powder of Mg,Ni,RE and sintering under the protection o...A series of Mg_(2-x)Nd_xNi (x=0.05, 0.1, 0.2, 0.3) alloys and Mg_(1.95)RE_(0.05)Ni (RE= La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixted powder of Mg,Ni,RE and sintering under the protection of argon. XRD analysis shows that Mg_(2-x)Nd_xNi (x=0.05, 0.1) and Mg_(1.95)RE_(0.05)Ni consist of single phase with the same crystal structure as Mg_2Ni. While three-phase alloys including Mg_2Ni, NdNi and NdMgNi_4 were formed in Mg_(1.8)Nd_(0.2)Ni and Mg_(1.7)Nd_(0.3)Ni alloys respectively. The lattice constants of Mg_2Ni in those ternary alloys were calculated. The decomposition of Mg_2Ni occurs in the milling process of Mg_2Ni and Mg_(1.95)RE_(0.05) Ni alloys respectively. For the latter, another earlier reaction occurs in milling process, which means that atoms of RE are separated from crystal structure of Mg_2Ni and form relevant oxides by combination with oxygen existed in argon atmosphere.展开更多
A series of Mg_(2-x)Cr_xNi alloy powder has been produced by combination ofsolid-state diffusion with mechanical grinding (MG). X-ray diffraction patterns show that the alloypowders have an amorphous structure and gre...A series of Mg_(2-x)Cr_xNi alloy powder has been produced by combination ofsolid-state diffusion with mechanical grinding (MG). X-ray diffraction patterns show that the alloypowders have an amorphous structure and great increase in the specific surface. Electrochemicaldetection results indicate that the partial substitution of Mg by Cr in Mg_2Ni alloy improves thecycle life of this alloy greatly, which gets up to 100 cycles at 200 mA/g mass discharge current,keeping its mass discharge capacity over 200 mA.h/g. In the meanwhile, partial replacement of Mg byCr also increases the mass discharge capacity compared with Mg_2Ni alloy. With the increasing ofmass discharge current and content of Cr in Mg_(2-x)Cr_xNi, the cycle life of the alloys areincreased and the decay of mass discharge capacity slows down.展开更多
基金This work is supported by the State Key Project for Fundamental Research (TG2000026406) and the National Natural Science Foundation of China (No. 50071053).
文摘A new approach of ball-milled Mg_2Ni in tetrahydrofuran (THF) to improve thehydriding kinetics of Mg_2Ni alloy is suggested and studied. It is found that the modified alloydisplayed the improved activity for hydriding even at relatively low temperature (e.g., 323-373 K).In the case of the sample milled in THF for 20 h, the hydrogen content (mass fraction) reaches 1.6 %at 323 K, 2.1% at 348 K and 3.4% at 448 K, respectively. The use of THF during grinding led to thechange of the structure, which is reflected by the broadening and weakening of the diffraction peaksin the XRD spectra. The XPS analysis shows that Mg (2s) binding energy peak of Mg_2Ni aftermodification shifted from a lower binding energy to a higher one, indicating the charge transferencebetween Mg and THF and the formation of catalytically active electron donor-acceptor (EDA)complexes on the surface of modified Mg_2Ni alloy.
文摘A series of Mg_(2-x)Nd_xNi (x=0.05, 0.1, 0.2, 0.3) alloys and Mg_(1.95)RE_(0.05)Ni (RE= La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixted powder of Mg,Ni,RE and sintering under the protection of argon. XRD analysis shows that Mg_(2-x)Nd_xNi (x=0.05, 0.1) and Mg_(1.95)RE_(0.05)Ni consist of single phase with the same crystal structure as Mg_2Ni. While three-phase alloys including Mg_2Ni, NdNi and NdMgNi_4 were formed in Mg_(1.8)Nd_(0.2)Ni and Mg_(1.7)Nd_(0.3)Ni alloys respectively. The lattice constants of Mg_2Ni in those ternary alloys were calculated. The decomposition of Mg_2Ni occurs in the milling process of Mg_2Ni and Mg_(1.95)RE_(0.05) Ni alloys respectively. For the latter, another earlier reaction occurs in milling process, which means that atoms of RE are separated from crystal structure of Mg_2Ni and form relevant oxides by combination with oxygen existed in argon atmosphere.
文摘A series of Mg_(2-x)Cr_xNi alloy powder has been produced by combination ofsolid-state diffusion with mechanical grinding (MG). X-ray diffraction patterns show that the alloypowders have an amorphous structure and great increase in the specific surface. Electrochemicaldetection results indicate that the partial substitution of Mg by Cr in Mg_2Ni alloy improves thecycle life of this alloy greatly, which gets up to 100 cycles at 200 mA/g mass discharge current,keeping its mass discharge capacity over 200 mA.h/g. In the meanwhile, partial replacement of Mg byCr also increases the mass discharge capacity compared with Mg_2Ni alloy. With the increasing ofmass discharge current and content of Cr in Mg_(2-x)Cr_xNi, the cycle life of the alloys areincreased and the decay of mass discharge capacity slows down.
