ThMn_(12)-type iron-rich rare-earth permanent magnetic materials have garnered significant attention due to their exceptional intrinsic magnetic properties.However,challenges such as the metastable nature of the ThMn1...ThMn_(12)-type iron-rich rare-earth permanent magnetic materials have garnered significant attention due to their exceptional intrinsic magnetic properties.However,challenges such as the metastable nature of the ThMn12-type phase,excessively small single-domain grain size,and complex fabrication processes have hindered the achievement of high phase purity,uniform microstructure,and desirable extrinsic performance.In this study,we directly synthesized ThMn_(12)-type Sm_(0.8)Zr_(0.2)Fe_(11)SiB_(x)(x=0-0.2)ribbon magnets via boron doping combined with a one-step rapid solidification method.This approach not only simplifies the fabrication process but also enhances phase stability and achieves a uniform microstructure with high ThMn12-type phase purity.By optimizing the boron content and cooling rate,the resulting magnets exhibit a coercivity(H_(c))of 6222 Oe,a remanence(M_(r))of 80 emu/g,and a remanence ratio(M_(r)/M_(s))of 0.71.This work demonstrates a streamlined approach to producing high-performance ThMn12-type magnets and provides insights into their practical application potential.展开更多
The electrochemical properties of the as-cast and ball-milled CeMg12+x%(mass fraction) Ni (vs. CeMg12) (x=0, 50, 100 and 200) composites were investigated. The microstructure and discharge capacity of the ball-milled ...The electrochemical properties of the as-cast and ball-milled CeMg12+x%(mass fraction) Ni (vs. CeMg12) (x=0, 50, 100 and 200) composites were investigated. The microstructure and discharge capacity of the ball-milled CeMg12+x%Ni composites differ greatly depending on the amount of Ni introduced during ball-milling. The more nickel powder added, the more advantageous for the formation of the amorphous structure. And the discharge capacities of the ball-milled composites increase with increasing amount of nickel added. After 90 h ball-milling, the CeMg12+200% Ni composite exhibits a high discharge capacity of 1170 mAh·g-1(CeMg12)-1 at 303 K. The improvement of electrochemical capacity is attributed to the formation of a homogeneous amorphous structure as well as the modification of the surface state after Ni addition.展开更多
The substituting Mg with Ni and milling as-cast alloy with Ni were adopted to obtain nanocrystalline/amorphous CeMgnNi＋x wt.%Ni（x=100,200） alloys and promote the electrochemical hydrogen storage performances of Ce...The substituting Mg with Ni and milling as-cast alloy with Ni were adopted to obtain nanocrystalline/amorphous CeMgnNi＋x wt.%Ni（x=100,200） alloys and promote the electrochemical hydrogen storage performances of CeMg_（12）-type alloys.Analyzing the structural features of the alloys provided a mechanism for ameliorating the electrochemical hydrogen storage properties.The electrochemical tests demonstrated that all the alloys just needed one cycle to be activated.Rising Ni proportion had an obvious role on charge-discharge reaction.The discharge capacities of the as-milled（60 h） alloys increased sharply from 182.0 mAh/gfor x=100 alloy to 1010.2 mAh/gfor x=200 alloy at current density of 60 mAh/g.Furthermore,milling time largely determined the performances of electrochemical reaction.The discharge capacity continued to grow along with prolonging milling time,while the cycle stability obviously decreased for x=100 alloy,and first declined and then augmented for the x=200 alloy with milling time extending.In addition,there was an optimal value with milling time varying for the high rate discharge abilities（HRD）,which was 80.3%for x=100 alloys and 86.73%for x=200,respectively.展开更多
The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and s...The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.展开更多
The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and s...The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.展开更多
To improve the hydrogen storage performance of CeMg12-type alloys, partially substituting Mg with Ni in the alloy was conducted. The way to synthesize the target alloy powders was the mechanical milling method, by whi...To improve the hydrogen storage performance of CeMg12-type alloys, partially substituting Mg with Ni in the alloy was conducted. The way to synthesize the target alloy powders was the mechanical milling method, by which the CeMg11-Ni ＋ x wt% Ni （x = 100, 200） alloy powders with nanocrystalline and amorphous structure were obtained. The influence of the milling time and Ni content on the hydrogen storage properties of the alloys was discussed. The X-ray diffractometer and high-resolution transmission electron microscope were used to investigate the microstructures of the ball-milled alloys. The hydrogenation/dehydrogenation dynamics were studied using a Sievert instrument and a differential scanning calorimeter which was linked with a H2 detector. The hydrogen desorption activation energies of the alloy hydrides were evaluated by Arrhenius and Kissinger equations. From the results point of views, there is a little decline in the thermo- dynamic parameters （enthalpy and entropy changes） with the increase in Ni content. However, the alloys desorption and absorption dynamics are improved distinctly. What is more, the variation of milling time results in a dramatic influence on the hydrogen storage performances of alloys. Various maximum values of the hydrogen capacities correspond to different milling time, which are 5.805 and 6.016 wt% for the CeMgllNi ＋ x wt% Ni （x = 100, 200） alloys, respectively. The kinetics tests suggest that the hydrogen absorption rates increase firstly and then decrease with prolonging the milling time. The improvement of the gaseous hydrogen storage kinetics results from the decrease in the activation energy caused by the increase in Ni content and milling time.展开更多
The PrMg12-type composite alloy of PrMg_(11)Ni + x wt% Ni (x=100,200) with an amorphous and nanocrystalline microstructure were synthesized through the mechanical milling.Effects of milling duration and Ni content on ...The PrMg12-type composite alloy of PrMg_(11)Ni + x wt% Ni (x=100,200) with an amorphous and nanocrystalline microstructure were synthesized through the mechanical milling.Effects of milling duration and Ni content on the microstructures and electrochemical hydrogen storage performances of the ball-milled alloys were methodically studied.The ball-milled alloys obtain the optimum discharge capacities at the first cycle.Increasing Ni content dramatically enhances the electrochemical property of alloys.Milling time varying may obviously impact the electrochemical performance of these alloys.The discharge capacities show a significant upward trend with milling duration prolonging,but milling for a longer time more than 40 h induces a slight decrease in the discharge capacity of the x=200 alloy.As milling duration increases,the cycle stability clearly lowers,while it first declines and then augments under the same condition for the x=200 alloy.The high-rate discharge abilities of the ball-milled alloys show the optimum values with milling time varying.展开更多
A systematical investigation was carried out on structure and magnetic properties in SmFe_(9-x)V_(x)(x=0.4,0.8,1.2)compounds prepared by a single-roller quenching method.The high cool-down rate leads to metastable TbC...A systematical investigation was carried out on structure and magnetic properties in SmFe_(9-x)V_(x)(x=0.4,0.8,1.2)compounds prepared by a single-roller quenching method.The high cool-down rate leads to metastable TbCu_(7) phase in the parent compound,which gradually transforms into equilibrium ThMn_(12) structure with V-doping content increasing.The Curie temperature increases from 470 to 590 K with V doping,which is consistent with the phase transformation.Surprisingly,simultaneous increase in both coercivity and remanence is resulted by V doping,reaching the highest value of 685 kA·m^(-1)and 44.8×10^(-3)A·m^(2)·g^(-1)in x=1.2 compound,respectively.This phenomenon can be explained by the combination of phase transformation and intergranular exchange coupling throughδM-H plots.展开更多
基金Project supported by the National Key R&D Program of China(Grant Nos.2021YFB3500300 and 2023YFB3507000)the Scientific Research Foundation of the High Education Institutions for Distinguished Young Scholars in Anhui Province(Grant No.2022AH020012)+1 种基金partially supported by the Innovation Project for Overseas Researcher in Anhui Province(Grant No.2022LCX004)the facilities at the Center of Free Electron Laser&High Magnetic Field(FEL&HMF)in Anhui University。
文摘ThMn_(12)-type iron-rich rare-earth permanent magnetic materials have garnered significant attention due to their exceptional intrinsic magnetic properties.However,challenges such as the metastable nature of the ThMn12-type phase,excessively small single-domain grain size,and complex fabrication processes have hindered the achievement of high phase purity,uniform microstructure,and desirable extrinsic performance.In this study,we directly synthesized ThMn_(12)-type Sm_(0.8)Zr_(0.2)Fe_(11)SiB_(x)(x=0-0.2)ribbon magnets via boron doping combined with a one-step rapid solidification method.This approach not only simplifies the fabrication process but also enhances phase stability and achieves a uniform microstructure with high ThMn12-type phase purity.By optimizing the boron content and cooling rate,the resulting magnets exhibit a coercivity(H_(c))of 6222 Oe,a remanence(M_(r))of 80 emu/g,and a remanence ratio(M_(r)/M_(s))of 0.71.This work demonstrates a streamlined approach to producing high-performance ThMn12-type magnets and provides insights into their practical application potential.
文摘The electrochemical properties of the as-cast and ball-milled CeMg12+x%(mass fraction) Ni (vs. CeMg12) (x=0, 50, 100 and 200) composites were investigated. The microstructure and discharge capacity of the ball-milled CeMg12+x%Ni composites differ greatly depending on the amount of Ni introduced during ball-milling. The more nickel powder added, the more advantageous for the formation of the amorphous structure. And the discharge capacities of the ball-milled composites increase with increasing amount of nickel added. After 90 h ball-milling, the CeMg12+200% Ni composite exhibits a high discharge capacity of 1170 mAh·g-1(CeMg12)-1 at 303 K. The improvement of electrochemical capacity is attributed to the formation of a homogeneous amorphous structure as well as the modification of the surface state after Ni addition.
基金supported by the National Natural Science Foundations of China(51161015,51371094,51471054)Natural Science Foundation of Inner Mongolia,China(2015MS0558)
文摘The substituting Mg with Ni and milling as-cast alloy with Ni were adopted to obtain nanocrystalline/amorphous CeMgnNi＋x wt.%Ni（x=100,200） alloys and promote the electrochemical hydrogen storage performances of CeMg_（12）-type alloys.Analyzing the structural features of the alloys provided a mechanism for ameliorating the electrochemical hydrogen storage properties.The electrochemical tests demonstrated that all the alloys just needed one cycle to be activated.Rising Ni proportion had an obvious role on charge-discharge reaction.The discharge capacities of the as-milled（60 h） alloys increased sharply from 182.0 mAh/gfor x=100 alloy to 1010.2 mAh/gfor x=200 alloy at current density of 60 mAh/g.Furthermore,milling time largely determined the performances of electrochemical reaction.The discharge capacity continued to grow along with prolonging milling time,while the cycle stability obviously decreased for x=100 alloy,and first declined and then augmented for the x=200 alloy with milling time extending.In addition,there was an optimal value with milling time varying for the high rate discharge abilities（HRD）,which was 80.3%for x=100 alloys and 86.73%for x=200,respectively.
文摘The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.
文摘The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.
文摘To improve the hydrogen storage performance of CeMg12-type alloys, partially substituting Mg with Ni in the alloy was conducted. The way to synthesize the target alloy powders was the mechanical milling method, by which the CeMg11-Ni ＋ x wt% Ni （x = 100, 200） alloy powders with nanocrystalline and amorphous structure were obtained. The influence of the milling time and Ni content on the hydrogen storage properties of the alloys was discussed. The X-ray diffractometer and high-resolution transmission electron microscope were used to investigate the microstructures of the ball-milled alloys. The hydrogenation/dehydrogenation dynamics were studied using a Sievert instrument and a differential scanning calorimeter which was linked with a H2 detector. The hydrogen desorption activation energies of the alloy hydrides were evaluated by Arrhenius and Kissinger equations. From the results point of views, there is a little decline in the thermo- dynamic parameters （enthalpy and entropy changes） with the increase in Ni content. However, the alloys desorption and absorption dynamics are improved distinctly. What is more, the variation of milling time results in a dramatic influence on the hydrogen storage performances of alloys. Various maximum values of the hydrogen capacities correspond to different milling time, which are 5.805 and 6.016 wt% for the CeMgllNi ＋ x wt% Ni （x = 100, 200） alloys, respectively. The kinetics tests suggest that the hydrogen absorption rates increase firstly and then decrease with prolonging the milling time. The improvement of the gaseous hydrogen storage kinetics results from the decrease in the activation energy caused by the increase in Ni content and milling time.
基金Funded by National Natural Science Foundation of China(Nos.51871125,51901105 and 51761032)Inner Mongolia Natural Science Foundation(No.2019BS05005)。
文摘The PrMg12-type composite alloy of PrMg_(11)Ni + x wt% Ni (x=100,200) with an amorphous and nanocrystalline microstructure were synthesized through the mechanical milling.Effects of milling duration and Ni content on the microstructures and electrochemical hydrogen storage performances of the ball-milled alloys were methodically studied.The ball-milled alloys obtain the optimum discharge capacities at the first cycle.Increasing Ni content dramatically enhances the electrochemical property of alloys.Milling time varying may obviously impact the electrochemical performance of these alloys.The discharge capacities show a significant upward trend with milling duration prolonging,but milling for a longer time more than 40 h induces a slight decrease in the discharge capacity of the x=200 alloy.As milling duration increases,the cycle stability clearly lowers,while it first declines and then augments under the same condition for the x=200 alloy.The high-rate discharge abilities of the ball-milled alloys show the optimum values with milling time varying.
基金financially supported by the National High Technology Research and Development Program of China (No. 2011AA03A402)
文摘A systematical investigation was carried out on structure and magnetic properties in SmFe_(9-x)V_(x)(x=0.4,0.8,1.2)compounds prepared by a single-roller quenching method.The high cool-down rate leads to metastable TbCu_(7) phase in the parent compound,which gradually transforms into equilibrium ThMn_(12) structure with V-doping content increasing.The Curie temperature increases from 470 to 590 K with V doping,which is consistent with the phase transformation.Surprisingly,simultaneous increase in both coercivity and remanence is resulted by V doping,reaching the highest value of 685 kA·m^(-1)and 44.8×10^(-3)A·m^(2)·g^(-1)in x=1.2 compound,respectively.This phenomenon can be explained by the combination of phase transformation and intergranular exchange coupling throughδM-H plots.
