在353K的乙酰胺-尿素-N aB r熔体中,P t、Cu电极上,Co(Ⅱ)+2e→Co(0)是一步完全不可逆反应,测得0.060m o l.L-1CoC l2-乙酰胺-尿素-N aB r中,Co(Ⅱ)在P t上,传递系数α=0.28,扩散系数D0=4.68×10-5cm2.-s 1,Cu上α=0.28,D0=4.06...在353K的乙酰胺-尿素-N aB r熔体中,P t、Cu电极上,Co(Ⅱ)+2e→Co(0)是一步完全不可逆反应,测得0.060m o l.L-1CoC l2-乙酰胺-尿素-N aB r中,Co(Ⅱ)在P t上,传递系数α=0.28,扩散系数D0=4.68×10-5cm2.-s 1,Cu上α=0.28,D0=4.06×1-0 7cm2.-s 1。G d(Ⅲ)不能单独还原为G d(0),但可以被Co(Ⅱ)诱导共沉积。由恒电位电解法得到非晶态的G d-Co合金,G d的含量随阴极电位的负移,G d(Ⅲ)/N i(Ⅱ)摩尔比增大以及电解时间延长而增大。展开更多
Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduct...Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduction of Co^2＋ is an irreversible process. Gd^3＋ cannot be reduced alone, but it can be inductively co-deposited with Co^2＋. Both the Gd content and microstructure of the prepared Gd-Co alloy films can be controlled by the deposited potential. The content of Gd was analyzed using an inductively coupled plasma emission spectrometer （ICPES）, and the microstructure was observed by scanning electron micrograph （SEM）. The films were crystallized by heat-treatment at 823 K for 30 s in Ar atmosphere, and then were investigated by XRD. The hysteresis loops of the Gd-Co alloy films were measured by a vibrating sample magnetometer （VSM）. The experimental results reveal that the deposited Gd-Co alloy films are amorphous, while the annealing causes the samples to change from amorphous to polycrystalline, thus enhancing their magnetocrystalline anisotropy and coercivity. Moreover, the magnetic properties of the Gd-Co alloy films depend strongly on the Gd content.展开更多
The glass-forming ability （CFA） and magnetic properties of the Cd50 Co50-based amorphous alloy with AI addition substitution for Co are investigated. It is found that the CFA and magneto-caloric effect of the Gd50Co...The glass-forming ability （CFA） and magnetic properties of the Cd50 Co50-based amorphous alloy with AI addition substitution for Co are investigated. It is found that the CFA and magneto-caloric effect of the Gd50Co45Al5 amorphous alloy are better than Cd50Co50 amorphous alloy. The maximum magnetic entropy change （-△ Sm^peak） and the magnetic refrigerant capacity- of the amorphous alloy under a field of 5 T are about 6.64 J·kg^-1 K^-1 and 764 J·kg^-1, respectively. The field dependence of magnetic entropy change meets the one predicted by the mean field theory, which is investigated for a better understanding of the magneto-caloric behaviors of the Gdso Co45Al5 amorphous alloy.展开更多
The Gd-Co-Mn alloys with compositions of Gd33.3Co66.7, Gd33.3Mn66.7, Gd22.2Co74.8Mn3 and Gd25Co70Mn5 were prepared and examined by X-ray diffractometer. The electrochemical properties of these alloys such as discharge...The Gd-Co-Mn alloys with compositions of Gd33.3Co66.7, Gd33.3Mn66.7, Gd22.2Co74.8Mn3 and Gd25Co70Mn5 were prepared and examined by X-ray diffractometer. The electrochemical properties of these alloys such as discharge capacity, cycling performance and high rate dischargeability were investigated by battery testing instruments in alkaline electrolyte. The discharge capacity of Gd22.2Co74.8Mn3 was the highest among these alloys at the same discharge current density, and the maximum value was 376.7 mAh/g discharged at 150 mA/g. The discharge capacities of the alloys Gd33.3Co66.7 and Gd33.3Mn66.7 reached their maxima （about 225 and 325 mAh/g） at discharge current density of 150 mA/g. A comparison of the electrochemical performance of the Gd-Co-Mn alloys revealed that the alloy Gd22.2Co74.sMn3 possessed better electrochemical performance and had better discharge capacity, cycle stability, while the alloy Gd25Co70Mn5 had a better high rate discharge ability. In general, the electrochemical performance of ternary alloys was better than binary alloys in this case.展开更多
In this work,neodymium substituted gadolinium-cobalt ferrite nanoparticles were synthesized by hydrothermal method.The significant role of doping both the Nd3+and Gd3+ions to cobalt ferrite in manipulating the cation ...In this work,neodymium substituted gadolinium-cobalt ferrite nanoparticles were synthesized by hydrothermal method.The significant role of doping both the Nd3+and Gd3+ions to cobalt ferrite in manipulating the cation distribution and further in influencing structural and magnetic properties was experimentally studied and reported.The influence of Nd3+substitution was investigated with step of 0.02-0.1 into the optimized Gd-Co compound.The crystal structure formation and crystallite size were explored by X-ray diffraction analysis in which the crystallite size and lattice constant decrease with increasing the Nd3+substitution.The microstructural properties were studied by field emission scanning electron microscopy and atomic force microscopy studies.The obtained structural and morphological results reveal that the substitution of Nd3+with more than 0.06 into the Gd-Co ferrites will change the material be havior and trends.The saturation magnetization and coercivity values were measured using a vibration sample magnetometer at room temperature.Comparative microwave absorption experiments demonstrate that the reflection loss properties enhance with increasing substitution of Nd3+cations in Gd-Co ferrite spinel structure.This research reports that the as-prepared Nd3+substituted Gd-Co ferrite compound stands as promising candidate for absorbing electromagnetic wave with a wider absorbing bandwidth of X-band.展开更多
基金financially supported by the Science Foundation of the Educational Department of Fujian Prov-ince (No. 2008F5021)the Natural Science Foundation of Fujian Province (No. A0510013)the National Natural Science Foundation of China (No. 60676055)
文摘Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduction of Co^2＋ is an irreversible process. Gd^3＋ cannot be reduced alone, but it can be inductively co-deposited with Co^2＋. Both the Gd content and microstructure of the prepared Gd-Co alloy films can be controlled by the deposited potential. The content of Gd was analyzed using an inductively coupled plasma emission spectrometer （ICPES）, and the microstructure was observed by scanning electron micrograph （SEM）. The films were crystallized by heat-treatment at 823 K for 30 s in Ar atmosphere, and then were investigated by XRD. The hysteresis loops of the Gd-Co alloy films were measured by a vibrating sample magnetometer （VSM）. The experimental results reveal that the deposited Gd-Co alloy films are amorphous, while the annealing causes the samples to change from amorphous to polycrystalline, thus enhancing their magnetocrystalline anisotropy and coercivity. Moreover, the magnetic properties of the Gd-Co alloy films depend strongly on the Gd content.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171100 and 51271103the Research Grants Council of the Hong Kong Special Administrative Region under Grant No PolyU511212
文摘The glass-forming ability （CFA） and magnetic properties of the Cd50 Co50-based amorphous alloy with AI addition substitution for Co are investigated. It is found that the CFA and magneto-caloric effect of the Gd50Co45Al5 amorphous alloy are better than Cd50Co50 amorphous alloy. The maximum magnetic entropy change （-△ Sm^peak） and the magnetic refrigerant capacity- of the amorphous alloy under a field of 5 T are about 6.64 J·kg^-1 K^-1 and 764 J·kg^-1, respectively. The field dependence of magnetic entropy change meets the one predicted by the mean field theory, which is investigated for a better understanding of the magneto-caloric behaviors of the Gdso Co45Al5 amorphous alloy.
基金National Natural Science Foundation of China(50861005,50961002)Natural Science Foundation of Guangxi(2011GXNSFD018005)Plan of the Top Innovation Team Construction of Guangxi University(31)
文摘The Gd-Co-Mn alloys with compositions of Gd33.3Co66.7, Gd33.3Mn66.7, Gd22.2Co74.8Mn3 and Gd25Co70Mn5 were prepared and examined by X-ray diffractometer. The electrochemical properties of these alloys such as discharge capacity, cycling performance and high rate dischargeability were investigated by battery testing instruments in alkaline electrolyte. The discharge capacity of Gd22.2Co74.8Mn3 was the highest among these alloys at the same discharge current density, and the maximum value was 376.7 mAh/g discharged at 150 mA/g. The discharge capacities of the alloys Gd33.3Co66.7 and Gd33.3Mn66.7 reached their maxima （about 225 and 325 mAh/g） at discharge current density of 150 mA/g. A comparison of the electrochemical performance of the Gd-Co-Mn alloys revealed that the alloy Gd22.2Co74.sMn3 possessed better electrochemical performance and had better discharge capacity, cycle stability, while the alloy Gd25Co70Mn5 had a better high rate discharge ability. In general, the electrochemical performance of ternary alloys was better than binary alloys in this case.
基金Research Council of the University of Yasouj(Gryu-89131107)for financial support.
文摘In this work,neodymium substituted gadolinium-cobalt ferrite nanoparticles were synthesized by hydrothermal method.The significant role of doping both the Nd3+and Gd3+ions to cobalt ferrite in manipulating the cation distribution and further in influencing structural and magnetic properties was experimentally studied and reported.The influence of Nd3+substitution was investigated with step of 0.02-0.1 into the optimized Gd-Co compound.The crystal structure formation and crystallite size were explored by X-ray diffraction analysis in which the crystallite size and lattice constant decrease with increasing the Nd3+substitution.The microstructural properties were studied by field emission scanning electron microscopy and atomic force microscopy studies.The obtained structural and morphological results reveal that the substitution of Nd3+with more than 0.06 into the Gd-Co ferrites will change the material be havior and trends.The saturation magnetization and coercivity values were measured using a vibration sample magnetometer at room temperature.Comparative microwave absorption experiments demonstrate that the reflection loss properties enhance with increasing substitution of Nd3+cations in Gd-Co ferrite spinel structure.This research reports that the as-prepared Nd3+substituted Gd-Co ferrite compound stands as promising candidate for absorbing electromagnetic wave with a wider absorbing bandwidth of X-band.
