It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores(SMCs),with few studies reported on the influence of magnetic properties for o...It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores(SMCs),with few studies reported on the influence of magnetic properties for original powders with various average particle sizes less than 10m.In this work,SiO_(2)-coated FeSiCr SMCs with different small particle sizes were synthesized using the sol-gel process.The contribution of SiO_(2)coating amount and voids to the soft magnetic properties was elaborated.The mechanism was revealed such that smaller particle sizes with less voids could be beneficial for reducing core loss in the SMCs.By optimizing the core structure,permeability and magnetic loss of 26 and 262 kW/cm^(3)at 100 kHz and 50 mT were achieved at a particle size of 4.8m and ethyl orthosilicate addition of 0.1 mL/g.The best DC stacking performance,reaching 87%,was observed at an ethyl orthosilicate addition rate of 0.25 mL/g under 100 Oe.Compared to other soft magnetic composites(SMCs),the FeSiCr/SiO_(2)SMCs exhibit significantly reduced magnetic loss.It further reduces the magnetic loss of the powder core,providing a new strategy for applications of SMCs at high frequencies.展开更多
The unique cellular microstructure of Fe-rich Sm_(2)Co_(17)-type permanent magnets is closely associated with the structure of the solid solution precursor.We investigate the phase structure,magnetic properties,and me...The unique cellular microstructure of Fe-rich Sm_(2)Co_(17)-type permanent magnets is closely associated with the structure of the solid solution precursor.We investigate the phase structure,magnetic properties,and mechanical behavior of B-doped Sm_(2)Co_(17)-type magnets with high Fe content.The doped B atoms can diffuse into the interstitial vacancy,resulting in lattice expansion and promote the homogenization of the phase organizational structure during the solid solution treatment in theory.However,the resulting second phase plays a dominant role to result in more microtwin structures and highly ordered 2:17R phases in the solid solution stage,which inhibits the ordering transformation of 1:7H phase during aging and affects the generation of the cellular structure,and to result in a decrease in magnetic properties,yet the interface formed between it and the matrix phase hinders the movement of dislocations and enhances the mechanical properties.Hence,the precipitation of high flexural strain grain boundary phase induced by B element doping is also a new and effective way to improve the flexural strain of Sm_(2)Co_(17)-type magnets.Our study provides a new understanding of the phase structure evolution and its effect on the magnetic and mechanical properties of Sm_(2)Co_(17)-type magnets with high Fe content.展开更多
To improve the performance of Ni-Zn ferrites for power field use,the influence of MnO2 additive on the properties of Ni-Zn ferrites was investigated by the conventional powder metallurgy.The results show that MnO2 doe...To improve the performance of Ni-Zn ferrites for power field use,the influence of MnO2 additive on the properties of Ni-Zn ferrites was investigated by the conventional powder metallurgy.The results show that MnO2 does not form a visible second phase in the doping mass fraction range of(0-2.0%).The average grain size,sintering density and real permeability gradually decrease with the increase of the MnO2 content.And the DC resistivity continuously increases with the increase of MnO2 content.The saturation magnetization(magnetic moment in unit mass) first increases slightly when mass fraction of MnO2 is less than 0.4% MnO2,and then gradually decreases with increasing the MnO2 mass fraction due to the exchange interaction of the cations.When the excitation frequency is less than 1 MHz,the power loss(Pcv) continuously increases with increasing the MnO2 content due to the decrease of average grain size.However,when the excitation frequency exceeds 1 MHz,eddy current loss gradually becomes the predominant contribution to Pcv.And the sample with a higher resistivity favors a lower Pcv,except for the sample with 2.0% MnO2.The sample without additive has the best Pcv when worked at frequencies less than 1 MHz;and the sample with 1.6% MnO2 additive has the best Pcv when worked at frequencies higher than 1 MHz.展开更多
The two-dimensional(2D)Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures.Van der Waals CrCl_(3) monolayer has been experimentally proved to...The two-dimensional(2D)Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures.Van der Waals CrCl_(3) monolayer has been experimentally proved to have an in-plane magnetic easy axis and a low Curie temperature of 17 K,which will limit its application in spintronic devices.In this work,we propose a new Janus monolayer Cr_(2)Cl_(3)S_(3) based on the first principles calculations.The phonon dispersion and elastic constants confirm that Janus monolayer Cr_(2)Cl_(3)S_(3) is dynamically and mechanically stable.Our Monte Carlo simulation results based on magnetic exchange constants reveal that Janus monolayer Cr_(2)Cl_(3)S_(3) is an intrinsic ferromagnetic semiconductor with TC of 180 K,which is much higher than that of CrCl_(3) due to the enhanced ferromagnetic coupling caused by S substitution.Moreover,the magnetic easy axis of Janus Cr_(2)Cl_(3)S_(3) can be tuned to the perpendicular direction with a large magnetic anisotropy energy(MAE)of 142eV/Cr.Furthermore,the effect of biaxial strain on the magnetic property of Janus monolayer Cr_(2)Cl_(3)S_(3) is evaluated.It is found that the Curie temperature is more robust under tensile strain.This work indicates that the Janus monolayer Cr_(2)Cl_(3)S_(3) presents increased Curie temperature and out-of-plane magnetic easy axis,suggesting greater application potential in 2D spintronic devices.展开更多
Bismuth molybdate (Bi2MoO6) nano-particles (NPs) were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and...Bismuth molybdate (Bi2MoO6) nano-particles (NPs) were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and photocatalytic properties of the obtained powder were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray (EDX), ultraviolet-visible diffuse reflectance spectra (DRS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM) techniques. The XRD, FT-IR and EDX results indicate that the resultant powder is pure and single phase crystalline Bi2MoO6 with orthorhombic structure. The HRSEM image shows that the morphology of obtained powder consists with well defined nano-particles structure. The VSM results show superparamagnetic behavior of the obtained nano-particles. The photocatalytic activity of Bi2MoO6 nano-particles was performed. The addition of TiO2 catalyst enhances the photocatalytic activity of Bi2MoO6 nano-particles. The catalysts Bi2MoO6, TiO2 and mixed oxide catalyst Bi2MoO6-TiO2 nano-composites (NCs) were tested for the photocatalytic degradation (PCD) of 4-chlorophenol (4-CP). It is found that the PCD efficiency of Bi2MoO6-TiO2 NCs is higher than that of pure Bi2MoO6 and TiO2 catalysts.展开更多
We herein report two crystals based on 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or s...We herein report two crystals based on 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-(imidazo[1,2-a]pyridin-2-yl)- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions (hydrogen bonds, anion-Tr or lone- pair-~r interactions), leading to low magnetic susceptibilities. 2-(imidazo[1,2-a]pyridin-2-yl)- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.展开更多
We present a detailed investigation of magnetic properties of colossal magnetoresistance material HgCr2Se4. While spontaneous magnetization and zero-field magnetic susceptibility are found to follow asymptotic scaling...We present a detailed investigation of magnetic properties of colossal magnetoresistance material HgCr2Se4. While spontaneous magnetization and zero-field magnetic susceptibility are found to follow asymptotic scaling laws for a narrow range of temperatures near the critical point, two methods with connections to the renormalization group theory provide analytical descriptions of the magnetic properties for much wider temperature ranges. Based on this, an analytical formula is obtained for the temperature dependence of the low field magnetoresistance in the paramagnetic phase.展开更多
The nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5,molar fraction) fibers with fine diameters and high aspect ratios(length to diameter ratios) were prepared by the organic gel-thermal decomposition process from...The nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5,molar fraction) fibers with fine diameters and high aspect ratios(length to diameter ratios) were prepared by the organic gel-thermal decomposition process from citric acid and metal salts.The structures and morphologies of gel precursors and fibers derived from thermal decomposition of the gel precursors were characterized by Fourier transform infrared spectroscopy,X-ray diffractometry and scanning electron microscopy.The magnetic properties of the nanocomposite fibers were measured by vibrating sample magnetometer.The nanocomposite fibers consisting of ferrite(CoFe2O4) and perovskite(BaTiO3) are formed at the calcination temperature of 900 ℃ for 2 h.The average grain sizes of CoFe2O4 and BaTiO3 in the nanocomposite fibers increase from 25 to 65 nm with the calcination temperature from 900 to 1 180 ℃.The single fiber constructed from these nanograins of CoFe2O4 and BaTiO3 has a necklace-like morphology.The saturation magnetization of the nanocomposite 0.4CoFe2O4-0.6BaTiO3 fibers increases with the increase of CoFe2O4 grain size,while the coercivity reaches a maximum value when the average grain size of CoFe2O4 is around the critical single-domain size of 45 nm obtained at 1 000 ℃.The saturation magnetization and remanence of the nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5) fibers almost exhibit a linear relationship with the molar fraction of CoFe2O4 in the nanocomposites.展开更多
A coordination polymer based on iron(II) carboxylate helical chains [Fe(bpdc)(H2O)2]n 1 has been constructed hydrothermally using H2bpdc (H2bpdc = 2,2'-bipyridine-4,4'-dicarboxylic acid), pyridine and FeSO4&...A coordination polymer based on iron(II) carboxylate helical chains [Fe(bpdc)(H2O)2]n 1 has been constructed hydrothermally using H2bpdc (H2bpdc = 2,2'-bipyridine-4,4'-dicarboxylic acid), pyridine and FeSO4·7H2O. Its crystal structure reveals that the Fe(Ⅱ) ion adopts a slightly distorted octahedron. The carboxylates of bpdc ligands alternately bridge the Fe(Ⅱ) cations to form 1D infinite helical chains. The Fe···Fe intrachain distance is 4.8246(6) . The adjacent chains are further interlinked by the coordination of bpdc ligands and hydrogen bonding to form a 3D framework. Magnetic studies for complex 1 show weak antiferromagnetic coupling between the Fe(Ⅱ) ions. The best-fit for χM T vs. T with a Hamiltonian∑∑==iBiiHJSi SigHS11 leadsto g = 2.314(4) and J = –0.68(1) cm-1.展开更多
Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid(H4bptc) with cobalt salt in the presence of 1,4-bis(2-pyridylmethyl)piperazin(bpmp) afforded one novel coordination polymer, namely, [Co(H2bptc...Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid(H4bptc) with cobalt salt in the presence of 1,4-bis(2-pyridylmethyl)piperazin(bpmp) afforded one novel coordination polymer, namely, [Co(H2bptc)(bpmp)0.5(H2O)]n(1). Its structure was established by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analysis. Complex 1 crystallizes in monoclinic, space group P21/c with a = 11.4839(11), b = 16.6690(16), c = 11.5559(11) A, V = 2201.8(4) A3, Mr = 539.35, Dc = 1.627 g/cm^3, μ(MoK α) = 0.841 mm-1, F(000) = 1108, Z = 4, the final R = 0.0309 and w R = 0.0705 for 4090 observed reflections(I 2σ(I)). Complex 1 displays a one-dimensional(1D) chain bridged by bpmp. Two carboxylic groups of H4 bptc ligand adopt μ01-η1:η1 and μ1-η1:η coordination modes to bridge adjacent Co(Ⅱ) ions together with bpmp ligand to give alternately arranged left- and right-handed helical chains. In addition, variable-temperature magnetic susceptibility measurements indicate that complex 1 shows weak antiferromagnetic interactions between the adjacent Co(Ⅱ) ions.展开更多
The effects of additive SnO2 (0.4wt.%), with and without SiO2 (0.02wt.%) and/or CaO (0.04wt.%), on the microstructure and magnetic properties of Mn-Zn ferrites were reported. The results reveal that SnO2 on its own in...The effects of additive SnO2 (0.4wt.%), with and without SiO2 (0.02wt.%) and/or CaO (0.04wt.%), on the microstructure and magnetic properties of Mn-Zn ferrites were reported. The results reveal that SnO2 on its own increases the initial permeability (μi) slightly, but SnO2 with SiO2 and/or CaO decreases the values of μi. However, ferrites with SnO2 additions have reduced power losses. The separate contributions of hysteresis loss and eddy current loss to the total power loss show that SnO2 (with or without SiO2 and/or CaO) doping increases the hysteresis loss slightly, but SnO2 doping alone reduces the eddy current loss significantly (~14%). The additions of SiO2 or CaO further decrease the eddy current loss, and by interaction of SnO2-CaO-SiO2, the eddy current loss is reduced by more than 20%. These magnetic and microstructural effects were discussed in terms of the additive-impurity interaction, the existence of grain boundary phases, and the effective bulk and grain boundary resistivities of the ferrites.展开更多
Hysteresis loops,energy products and magnetic moment distributions of perpendicularly oriented Nd2Fe(14)B/α-Fe exchange-spring multilayers are studied systematically based on both three-dimensional(3D)and one-dimensi...Hysteresis loops,energy products and magnetic moment distributions of perpendicularly oriented Nd2Fe(14)B/α-Fe exchange-spring multilayers are studied systematically based on both three-dimensional(3D)and one-dimensional(1D)micromagnetic methods,focused on the influence of the interface anisotropy.The calculated results are carefully compared with each other.The interface anisotropy effect is very palpable on the nucleation,pinning and coercive fields when the soft layer is very thin.However,as the soft layer thickness increases,the pinning and coercive fields are almost unchanged with the increment of interface anisotropy though the nucleation field still monotonically rises.Negative interface anisotropy decreases the maximum energy products and increases slightly the angles between the magnetization and applied field.The magnetic moment distributions in the thickness direction at various applied fields demonstrate a progress of three-step magnetic reversal,i.e.,nucleation,evolution and irreversible motion of the domain wall.The above results calculated by two models are in good agreement with each other.Moreover,the in-plane magnetic moment orientations based on two models are different.The 3D calculation shows a progress of generation and disappearance of vortex state,however,the magnetization orientations within the film plane calculated by the 1D model are coherent.Simulation results suggest that negative interface anisotropy is necessarily avoided experimentally.展开更多
A new ternary neodymium zirconium sulfide Nd_2ZrS_5 was synthesized by high-temperature solid-state reaction and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic spac...A new ternary neodymium zirconium sulfide Nd_2ZrS_5 was synthesized by high-temperature solid-state reaction and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic space group Pnma(No. 62) belonging to the Y_2HfS_5 structure-type with a = 11.461(4), b = 8.009(3), c = 7.315(3) A, Z = 2 and V = 671.5(4)A3. Its structure features NdS_8 and ZrS_7 polyhedra-constructed a 3-D network. The data of magnetic susceptibility indicate its antiferromagnetic-like behavior without magnetic order down to 2 K.展开更多
A new europium(III) complex Eu(L)3(Phen)2(1) with 2-benzoylbenzoic acid(HL) and 1,10-phenanthroline(Phen) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space gr...A new europium(III) complex Eu(L)3(Phen)2(1) with 2-benzoylbenzoic acid(HL) and 1,10-phenanthroline(Phen) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space group P21/c, a = 2.2577(4), b = 1.23484(19), c = 1.8789(3) nm, β = 94.918(3)o, V = 5.2189(14) nm^3, Dc = 1.512 g/cm^3, Z = 4, μ(Mo Kα) = 1.269 mm^-1, F(000) = 2408, the final R = 0.0433 and w R = 0.1038. The Eu(III) ion is coordinated by nine atoms to give a single-capped square antiprism coordination geometry. 1 shows two intense fluorescence emission bands arising from the transitions of Eu^3+: ^5D0→^7F1(597 nm) and ^5D0→^7F2(615 nm) with an excitation wavelength of 396 nm. In addition, 1 displays antiferromagnetic property at low temperature.展开更多
A new copper complex [Cu(pdc)(bpy)]·H2 O(1, H2 pdc = 3,5-pyridinedicarboxylic acid, bpy = 2,2-bipyridine) has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental...A new copper complex [Cu(pdc)(bpy)]·H2 O(1, H2 pdc = 3,5-pyridinedicarboxylic acid, bpy = 2,2-bipyridine) has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, UV-vis spectroscopy and magnetic measure- ments. Complex 1 crystallizes in monoclinic system, space group P21 /c, a = 10.893(2), b = 7.3641(15), c = 1.9921(4), β = 92.16(3), V = 1596.9(6)3, Dc = 1.676 g/cm3, Mr = 402.84, Z = 4, F(000) = 820, μ = 1.404 mm-1, the final R = 0.0237 and wR = 0.0693. The Cu(II) ion is five-coordinated by two O atoms from two pdc ligands, one N atom from another pdc ligand and two N atoms from the bpy ligand. The pdc anion, which acts as a tridentate ligand, links three Cu ions, forming(3,3)-connected two-dimensional(2D) sheets. We also studied the electronic structure and orbital energies of complex 1 by DFT methods, and the results are consistent with UV-vis spectrum.展开更多
One novel nickel coordination polymer, {[Ni(OTP)(bib)1.5(H2O)]·2H2O}n(1, H2 OTP = 2-hydroxy-5-(3',5'-terephthalic acid) pyridine, bib = 1,4-bis(1-imdazoly)benzene), has been synthesized and characte...One novel nickel coordination polymer, {[Ni(OTP)(bib)1.5(H2O)]·2H2O}n(1, H2 OTP = 2-hydroxy-5-(3',5'-terephthalic acid) pyridine, bib = 1,4-bis(1-imdazoly)benzene), has been synthesized and characterized by elemental analysis(EA), IR, powder X-ray diffraction(PXRD), and thermogravimetric(TG) analyses. The crystal of 1 crystallizes in monoclinic, space group P21/n with a = 12.2860(5), b = 13.8246(6), c = 19.0140(8) A, β = 104.3870(1)°, V = 3128.2(2) A3, Z = 4, C32H28N7 Ni O8, Mr = 697.32, Dc = 1.481 g/cm^3, F(000) = 1444 and μ(Mo Kα) = 0.684 mm-1. The final R = 0.0704 and w R = 0.1764 for 5485 observed reflections with I 2σ(I) and R = 0.1087 and wR = 0.2010 for all data. Topology analysis reveals that complex 1 is a 3D 2-fold interpenetrated {4^4·6^6}-nov net based on the 1D [Ni(OTP)]n chain and the 2D [Ni2(bib)3]n sql sheet. And the variable-temperature magnetic susceptibility measurements exhibit weak antiferromagnetic coupling interaction.展开更多
N-2-Thiazolylacrylamide (NTA) was polymerized by a radical route to obtain the polymer in good yield. The polymer with a pendent heterocyclic group is soluble in common organic solvents, which allow to prepare the c...N-2-Thiazolylacrylamide (NTA) was polymerized by a radical route to obtain the polymer in good yield. The polymer with a pendent heterocyclic group is soluble in common organic solvents, which allow to prepare the corresponding metal complexes with higher loads easily. FTIR, ^1H NMR, elemental analysis, and energy-dispersive X-Ray spectroscopy (EDX) were applied to characterize these materials. The magnetic behavior of Fe(Ⅱ) and Nd(Ⅲ) complexes of poly(N-2-thiazolylacrylamide) was examined by a PPMS-9T magnetometer, exhibiting the characteristics of a soft ferromagnet. It is found that the Nd(Ⅲ) complex has an extremely high relative saturation magnetization of 35 emu/g.展开更多
A new cadmium(II) complex Cd(OBBA)2(2,2A-bipy)2 with 2-benzoylbenzoic acid(HOBBA) and 2,2-bipyridine(2,2A-bipy) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space group P21...A new cadmium(II) complex Cd(OBBA)2(2,2A-bipy)2 with 2-benzoylbenzoic acid(HOBBA) and 2,2-bipyridine(2,2A-bipy) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space group P21/c with a = 16.402(3), b = 10.4191(18), c = 23.395(4) A, β = 91.765(2)o, V = 3996.2(12) A3, Dc = 1.455 gAcm-3, Z = 4, μ(Mo Kα) = 0.603 mm-1, F(000) = 1784, the final R = 0.0218 and w R = 0.0558. In the electrode reaction, its electron transfer is quasi reversible and the electrode reaction corresponds to Cd(II)/Cd(0). Under 618 nm radiation, the title complex shows a strong fluorescent band at around 326 nm. In addition, in the range of 2~300 K, this complex displays diamagnetic property.展开更多
The employment of N-hydroxy-pyridine-2-carboxamidine in the coordination chemistry of zinc(II), nickel(II) and manganese(II) under solvothermal conditions is reported. Four complexes of compositions, [Zn2(O2CMe...The employment of N-hydroxy-pyridine-2-carboxamidine in the coordination chemistry of zinc(II), nickel(II) and manganese(II) under solvothermal conditions is reported. Four complexes of compositions, [Zn2(O2CMe)3{(py)C(NH2)NOH}4](OH) (1), [Zn4(OH)2{(py)C(NH2)- NO}4CI2]'3MeCN (2), [Ni(SO4)(H20){(py)C(NH2)NOH}2]'H2O (3) and [Mn(SO4){(py)C(NH2)- NOH}2]n (4), have been synthesized by rationally choosing different metal salts and dexterously employing acetate and sulfate ions as the bridging groups. Luminescent properties for 2 suggested strong emission in the solid state at room temperature. Variable temperature (2.0-300 K) magnetic studies for the linear chain complex 4 indicate weak antiferromagnetic Mn(Ⅱ)...Mn(Ⅱ) exchange interactions.展开更多
CuFe2O4 nanotube arrays with different outer diameters were synthesized in anodic aluminum oxide templates through sol-gel techniques followed by heating treatment processes. The morphology of the nanotube arrays was ...CuFe2O4 nanotube arrays with different outer diameters were synthesized in anodic aluminum oxide templates through sol-gel techniques followed by heating treatment processes. The morphology of the nanotube arrays was investigated by field emission scanning electron microscope and transmission electron microscopy, suggesting that the nanotube arrays are ordered and uniform. The X-ray diffraction results indicate that the crystal structure of the nanotube arrays is polycrystalline with a spinel-type structure. The measurements of magnetic properties indicate that CuFe2O4 nanotube arrays with outer diameter of 200 nm exhibit magnetic anisotropy with easy magnetization direction along the axis of nanotubes.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U2230119 and U23A20567)2022 Central Guidance on Local Science and Technology Development Projects(Grant No.2022ZYDF073)Outstanding Youth Fund of Sichuan Province(Grant No.22JCQN0005).
文摘It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores(SMCs),with few studies reported on the influence of magnetic properties for original powders with various average particle sizes less than 10m.In this work,SiO_(2)-coated FeSiCr SMCs with different small particle sizes were synthesized using the sol-gel process.The contribution of SiO_(2)coating amount and voids to the soft magnetic properties was elaborated.The mechanism was revealed such that smaller particle sizes with less voids could be beneficial for reducing core loss in the SMCs.By optimizing the core structure,permeability and magnetic loss of 26 and 262 kW/cm^(3)at 100 kHz and 50 mT were achieved at a particle size of 4.8m and ethyl orthosilicate addition of 0.1 mL/g.The best DC stacking performance,reaching 87%,was observed at an ethyl orthosilicate addition rate of 0.25 mL/g under 100 Oe.Compared to other soft magnetic composites(SMCs),the FeSiCr/SiO_(2)SMCs exhibit significantly reduced magnetic loss.It further reduces the magnetic loss of the powder core,providing a new strategy for applications of SMCs at high frequencies.
基金the NationalKey R&D Program of China (Grant Nos. 2021YFB3503102and 2022YFB3505301)Science and Technology Innovation2025 Major Project of Ningbo (Grant No. 2022Z204)+2 种基金ZhejiangProvincial Natural Science Foundation Youth OriginalProject (Grant No. LDQ24E010001)the Key R&D Programof Shanxi Province (Grant No. 202302050201014)Ningbo Natural Science Foundation (Grant No. 2021J216).
文摘The unique cellular microstructure of Fe-rich Sm_(2)Co_(17)-type permanent magnets is closely associated with the structure of the solid solution precursor.We investigate the phase structure,magnetic properties,and mechanical behavior of B-doped Sm_(2)Co_(17)-type magnets with high Fe content.The doped B atoms can diffuse into the interstitial vacancy,resulting in lattice expansion and promote the homogenization of the phase organizational structure during the solid solution treatment in theory.However,the resulting second phase plays a dominant role to result in more microtwin structures and highly ordered 2:17R phases in the solid solution stage,which inhibits the ordering transformation of 1:7H phase during aging and affects the generation of the cellular structure,and to result in a decrease in magnetic properties,yet the interface formed between it and the matrix phase hinders the movement of dislocations and enhances the mechanical properties.Hence,the precipitation of high flexural strain grain boundary phase induced by B element doping is also a new and effective way to improve the flexural strain of Sm_(2)Co_(17)-type magnets.Our study provides a new understanding of the phase structure evolution and its effect on the magnetic and mechanical properties of Sm_(2)Co_(17)-type magnets with high Fe content.
基金Projects(50702011,60721001)supported by the National Natural Science Foundation of China
文摘To improve the performance of Ni-Zn ferrites for power field use,the influence of MnO2 additive on the properties of Ni-Zn ferrites was investigated by the conventional powder metallurgy.The results show that MnO2 does not form a visible second phase in the doping mass fraction range of(0-2.0%).The average grain size,sintering density and real permeability gradually decrease with the increase of the MnO2 content.And the DC resistivity continuously increases with the increase of MnO2 content.The saturation magnetization(magnetic moment in unit mass) first increases slightly when mass fraction of MnO2 is less than 0.4% MnO2,and then gradually decreases with increasing the MnO2 mass fraction due to the exchange interaction of the cations.When the excitation frequency is less than 1 MHz,the power loss(Pcv) continuously increases with increasing the MnO2 content due to the decrease of average grain size.However,when the excitation frequency exceeds 1 MHz,eddy current loss gradually becomes the predominant contribution to Pcv.And the sample with a higher resistivity favors a lower Pcv,except for the sample with 2.0% MnO2.The sample without additive has the best Pcv when worked at frequencies less than 1 MHz;and the sample with 1.6% MnO2 additive has the best Pcv when worked at frequencies higher than 1 MHz.
基金the National Natural Science Foundation of China(Grant No.12104234)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20210578,20KJB140004,and JSSCBS20210513)+4 种基金Y Pu acknowledges the National Natural Science Foundation of China(Grant Nos.61874060,U1932159,and 61911530220)Jiangsu Specially-Appointed Professor Program,the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20181388 and 19KJA180007)the Overseas Researcher Innovation Program of Nanjing,NUPTSF(Grant No.NY217118)F Li Acknowledges the Natural Science Fund for Colleges and Universities in Jiangsu Province,China(Grant No.21KJD140005)the National Natural Science Foundation of China(Grant No.12304085).
文摘The two-dimensional(2D)Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures.Van der Waals CrCl_(3) monolayer has been experimentally proved to have an in-plane magnetic easy axis and a low Curie temperature of 17 K,which will limit its application in spintronic devices.In this work,we propose a new Janus monolayer Cr_(2)Cl_(3)S_(3) based on the first principles calculations.The phonon dispersion and elastic constants confirm that Janus monolayer Cr_(2)Cl_(3)S_(3) is dynamically and mechanically stable.Our Monte Carlo simulation results based on magnetic exchange constants reveal that Janus monolayer Cr_(2)Cl_(3)S_(3) is an intrinsic ferromagnetic semiconductor with TC of 180 K,which is much higher than that of CrCl_(3) due to the enhanced ferromagnetic coupling caused by S substitution.Moreover,the magnetic easy axis of Janus Cr_(2)Cl_(3)S_(3) can be tuned to the perpendicular direction with a large magnetic anisotropy energy(MAE)of 142eV/Cr.Furthermore,the effect of biaxial strain on the magnetic property of Janus monolayer Cr_(2)Cl_(3)S_(3) is evaluated.It is found that the Curie temperature is more robust under tensile strain.This work indicates that the Janus monolayer Cr_(2)Cl_(3)S_(3) presents increased Curie temperature and out-of-plane magnetic easy axis,suggesting greater application potential in 2D spintronic devices.
文摘Bismuth molybdate (Bi2MoO6) nano-particles (NPs) were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and photocatalytic properties of the obtained powder were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray (EDX), ultraviolet-visible diffuse reflectance spectra (DRS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM) techniques. The XRD, FT-IR and EDX results indicate that the resultant powder is pure and single phase crystalline Bi2MoO6 with orthorhombic structure. The HRSEM image shows that the morphology of obtained powder consists with well defined nano-particles structure. The VSM results show superparamagnetic behavior of the obtained nano-particles. The photocatalytic activity of Bi2MoO6 nano-particles was performed. The addition of TiO2 catalyst enhances the photocatalytic activity of Bi2MoO6 nano-particles. The catalysts Bi2MoO6, TiO2 and mixed oxide catalyst Bi2MoO6-TiO2 nano-composites (NCs) were tested for the photocatalytic degradation (PCD) of 4-chlorophenol (4-CP). It is found that the PCD efficiency of Bi2MoO6-TiO2 NCs is higher than that of pure Bi2MoO6 and TiO2 catalysts.
基金This work was supported by the National Natural Science Foundation of China (No.21172210).
文摘We herein report two crystals based on 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-(imidazo[1,2-a]pyridin-2-yl)- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions (hydrogen bonds, anion-Tr or lone- pair-~r interactions), leading to low magnetic susceptibilities. 2-(imidazo[1,2-a]pyridin-2-yl)- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61425015,11474330 and 11374337the National Basic Research Program of China under Grant Nos 2012CB921703 and 2015CB921102the Chinese Academy of Sciences
文摘We present a detailed investigation of magnetic properties of colossal magnetoresistance material HgCr2Se4. While spontaneous magnetization and zero-field magnetic susceptibility are found to follow asymptotic scaling laws for a narrow range of temperatures near the critical point, two methods with connections to the renormalization group theory provide analytical descriptions of the magnetic properties for much wider temperature ranges. Based on this, an analytical formula is obtained for the temperature dependence of the low field magnetoresistance in the paramagnetic phase.
基金Project(50674048) supported by the National Natural Science Foundation of China Project(20080431069) supported by China Postdoctoral Science FoundationProject(CX10B-257Z) supported by Postgraduate Cultivation and Innovation Foundation of Jiangsu Province,China
文摘The nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5,molar fraction) fibers with fine diameters and high aspect ratios(length to diameter ratios) were prepared by the organic gel-thermal decomposition process from citric acid and metal salts.The structures and morphologies of gel precursors and fibers derived from thermal decomposition of the gel precursors were characterized by Fourier transform infrared spectroscopy,X-ray diffractometry and scanning electron microscopy.The magnetic properties of the nanocomposite fibers were measured by vibrating sample magnetometer.The nanocomposite fibers consisting of ferrite(CoFe2O4) and perovskite(BaTiO3) are formed at the calcination temperature of 900 ℃ for 2 h.The average grain sizes of CoFe2O4 and BaTiO3 in the nanocomposite fibers increase from 25 to 65 nm with the calcination temperature from 900 to 1 180 ℃.The single fiber constructed from these nanograins of CoFe2O4 and BaTiO3 has a necklace-like morphology.The saturation magnetization of the nanocomposite 0.4CoFe2O4-0.6BaTiO3 fibers increases with the increase of CoFe2O4 grain size,while the coercivity reaches a maximum value when the average grain size of CoFe2O4 is around the critical single-domain size of 45 nm obtained at 1 000 ℃.The saturation magnetization and remanence of the nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5) fibers almost exhibit a linear relationship with the molar fraction of CoFe2O4 in the nanocomposites.
基金Supported by Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University (MMM 200822)
文摘A coordination polymer based on iron(II) carboxylate helical chains [Fe(bpdc)(H2O)2]n 1 has been constructed hydrothermally using H2bpdc (H2bpdc = 2,2'-bipyridine-4,4'-dicarboxylic acid), pyridine and FeSO4·7H2O. Its crystal structure reveals that the Fe(Ⅱ) ion adopts a slightly distorted octahedron. The carboxylates of bpdc ligands alternately bridge the Fe(Ⅱ) cations to form 1D infinite helical chains. The Fe···Fe intrachain distance is 4.8246(6) . The adjacent chains are further interlinked by the coordination of bpdc ligands and hydrogen bonding to form a 3D framework. Magnetic studies for complex 1 show weak antiferromagnetic coupling between the Fe(Ⅱ) ions. The best-fit for χM T vs. T with a Hamiltonian∑∑==iBiiHJSi SigHS11 leadsto g = 2.314(4) and J = –0.68(1) cm-1.
基金supported by the National Natural Science Foundation of China(No.21273101 and 21302082)the Foundation of the Program for Backbone Teachers in Universities of Henan Province(No.2012GGJS158)
文摘Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid(H4bptc) with cobalt salt in the presence of 1,4-bis(2-pyridylmethyl)piperazin(bpmp) afforded one novel coordination polymer, namely, [Co(H2bptc)(bpmp)0.5(H2O)]n(1). Its structure was established by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analysis. Complex 1 crystallizes in monoclinic, space group P21/c with a = 11.4839(11), b = 16.6690(16), c = 11.5559(11) A, V = 2201.8(4) A3, Mr = 539.35, Dc = 1.627 g/cm^3, μ(MoK α) = 0.841 mm-1, F(000) = 1108, Z = 4, the final R = 0.0309 and w R = 0.0705 for 4090 observed reflections(I 2σ(I)). Complex 1 displays a one-dimensional(1D) chain bridged by bpmp. Two carboxylic groups of H4 bptc ligand adopt μ01-η1:η1 and μ1-η1:η coordination modes to bridge adjacent Co(Ⅱ) ions together with bpmp ligand to give alternately arranged left- and right-handed helical chains. In addition, variable-temperature magnetic susceptibility measurements indicate that complex 1 shows weak antiferromagnetic interactions between the adjacent Co(Ⅱ) ions.
文摘The effects of additive SnO2 (0.4wt.%), with and without SiO2 (0.02wt.%) and/or CaO (0.04wt.%), on the microstructure and magnetic properties of Mn-Zn ferrites were reported. The results reveal that SnO2 on its own increases the initial permeability (μi) slightly, but SnO2 with SiO2 and/or CaO decreases the values of μi. However, ferrites with SnO2 additions have reduced power losses. The separate contributions of hysteresis loss and eddy current loss to the total power loss show that SnO2 (with or without SiO2 and/or CaO) doping increases the hysteresis loss slightly, but SnO2 doping alone reduces the eddy current loss significantly (~14%). The additions of SiO2 or CaO further decrease the eddy current loss, and by interaction of SnO2-CaO-SiO2, the eddy current loss is reduced by more than 20%. These magnetic and microstructural effects were discussed in terms of the additive-impurity interaction, the existence of grain boundary phases, and the effective bulk and grain boundary resistivities of the ferrites.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0700900)the National Natural Science Foundation of China(Grant Nos.51571126 and 51861030)+1 种基金the Inner Mongolia Autonomous Region Natural Science Foundation of China(Grant No.2019MS01002)the Inner Mongolia Innovative Research Team of China(Grant No.3400102)。
文摘Hysteresis loops,energy products and magnetic moment distributions of perpendicularly oriented Nd2Fe(14)B/α-Fe exchange-spring multilayers are studied systematically based on both three-dimensional(3D)and one-dimensional(1D)micromagnetic methods,focused on the influence of the interface anisotropy.The calculated results are carefully compared with each other.The interface anisotropy effect is very palpable on the nucleation,pinning and coercive fields when the soft layer is very thin.However,as the soft layer thickness increases,the pinning and coercive fields are almost unchanged with the increment of interface anisotropy though the nucleation field still monotonically rises.Negative interface anisotropy decreases the maximum energy products and increases slightly the angles between the magnetization and applied field.The magnetic moment distributions in the thickness direction at various applied fields demonstrate a progress of three-step magnetic reversal,i.e.,nucleation,evolution and irreversible motion of the domain wall.The above results calculated by two models are in good agreement with each other.Moreover,the in-plane magnetic moment orientations based on two models are different.The 3D calculation shows a progress of generation and disappearance of vortex state,however,the magnetization orientations within the film plane calculated by the 1D model are coherent.Simulation results suggest that negative interface anisotropy is necessarily avoided experimentally.
基金Supported by Higher Education Science Foundation of Jiangsu Province(No.15KJB150031)State Key Laboratory of Structural Chemistry Fund(No.20150009)+1 种基金Yangzhou University for the start-up grantthe Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A new ternary neodymium zirconium sulfide Nd_2ZrS_5 was synthesized by high-temperature solid-state reaction and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic space group Pnma(No. 62) belonging to the Y_2HfS_5 structure-type with a = 11.461(4), b = 8.009(3), c = 7.315(3) A, Z = 2 and V = 671.5(4)A3. Its structure features NdS_8 and ZrS_7 polyhedra-constructed a 3-D network. The data of magnetic susceptibility indicate its antiferromagnetic-like behavior without magnetic order down to 2 K.
基金Supported by the Doctoral Scientific Research Foundation of Hengyang Normal University(16D06)the Open Fund Project of Key Laboratory of Functional Organometallic Materials of Hengyang Normal University(GN15K02)
文摘A new europium(III) complex Eu(L)3(Phen)2(1) with 2-benzoylbenzoic acid(HL) and 1,10-phenanthroline(Phen) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space group P21/c, a = 2.2577(4), b = 1.23484(19), c = 1.8789(3) nm, β = 94.918(3)o, V = 5.2189(14) nm^3, Dc = 1.512 g/cm^3, Z = 4, μ(Mo Kα) = 1.269 mm^-1, F(000) = 2408, the final R = 0.0433 and w R = 0.1038. The Eu(III) ion is coordinated by nine atoms to give a single-capped square antiprism coordination geometry. 1 shows two intense fluorescence emission bands arising from the transitions of Eu^3+: ^5D0→^7F1(597 nm) and ^5D0→^7F2(615 nm) with an excitation wavelength of 396 nm. In addition, 1 displays antiferromagnetic property at low temperature.
基金Supported by Natural Science Foundation of Hebei Province(No.E2013501135)program for New Century Excellent Talents in University(NCET-10-0304)
文摘A new copper complex [Cu(pdc)(bpy)]·H2 O(1, H2 pdc = 3,5-pyridinedicarboxylic acid, bpy = 2,2-bipyridine) has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, UV-vis spectroscopy and magnetic measure- ments. Complex 1 crystallizes in monoclinic system, space group P21 /c, a = 10.893(2), b = 7.3641(15), c = 1.9921(4), β = 92.16(3), V = 1596.9(6)3, Dc = 1.676 g/cm3, Mr = 402.84, Z = 4, F(000) = 820, μ = 1.404 mm-1, the final R = 0.0237 and wR = 0.0693. The Cu(II) ion is five-coordinated by two O atoms from two pdc ligands, one N atom from another pdc ligand and two N atoms from the bpy ligand. The pdc anion, which acts as a tridentate ligand, links three Cu ions, forming(3,3)-connected two-dimensional(2D) sheets. We also studied the electronic structure and orbital energies of complex 1 by DFT methods, and the results are consistent with UV-vis spectrum.
基金supported by the Natural Science Foundation of Shandong Province(ZR2011BL020,ZR2012CM019)National Natural Science Foundation of China(21451001)Key Discipline and Innovation Team of Qilu Normal University
文摘One novel nickel coordination polymer, {[Ni(OTP)(bib)1.5(H2O)]·2H2O}n(1, H2 OTP = 2-hydroxy-5-(3',5'-terephthalic acid) pyridine, bib = 1,4-bis(1-imdazoly)benzene), has been synthesized and characterized by elemental analysis(EA), IR, powder X-ray diffraction(PXRD), and thermogravimetric(TG) analyses. The crystal of 1 crystallizes in monoclinic, space group P21/n with a = 12.2860(5), b = 13.8246(6), c = 19.0140(8) A, β = 104.3870(1)°, V = 3128.2(2) A3, Z = 4, C32H28N7 Ni O8, Mr = 697.32, Dc = 1.481 g/cm^3, F(000) = 1444 and μ(Mo Kα) = 0.684 mm-1. The final R = 0.0704 and w R = 0.1764 for 5485 observed reflections with I 2σ(I) and R = 0.1087 and wR = 0.2010 for all data. Topology analysis reveals that complex 1 is a 3D 2-fold interpenetrated {4^4·6^6}-nov net based on the 1D [Ni(OTP)]n chain and the 2D [Ni2(bib)3]n sql sheet. And the variable-temperature magnetic susceptibility measurements exhibit weak antiferromagnetic coupling interaction.
基金This project is financially supported by the National Natural Science Foundation of China(No.20374044,20434020)
文摘N-2-Thiazolylacrylamide (NTA) was polymerized by a radical route to obtain the polymer in good yield. The polymer with a pendent heterocyclic group is soluble in common organic solvents, which allow to prepare the corresponding metal complexes with higher loads easily. FTIR, ^1H NMR, elemental analysis, and energy-dispersive X-Ray spectroscopy (EDX) were applied to characterize these materials. The magnetic behavior of Fe(Ⅱ) and Nd(Ⅲ) complexes of poly(N-2-thiazolylacrylamide) was examined by a PPMS-9T magnetometer, exhibiting the characteristics of a soft ferromagnet. It is found that the Nd(Ⅲ) complex has an extremely high relative saturation magnetization of 35 emu/g.
基金Supported by the Scientific Research Fund of Hunan Provincial Education Department(No.11C0186)the Construct Program of the Key Discipline in Hunan Province
文摘A new cadmium(II) complex Cd(OBBA)2(2,2A-bipy)2 with 2-benzoylbenzoic acid(HOBBA) and 2,2-bipyridine(2,2A-bipy) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space group P21/c with a = 16.402(3), b = 10.4191(18), c = 23.395(4) A, β = 91.765(2)o, V = 3996.2(12) A3, Dc = 1.455 gAcm-3, Z = 4, μ(Mo Kα) = 0.603 mm-1, F(000) = 1784, the final R = 0.0218 and w R = 0.0558. In the electrode reaction, its electron transfer is quasi reversible and the electrode reaction corresponds to Cd(II)/Cd(0). Under 618 nm radiation, the title complex shows a strong fluorescent band at around 326 nm. In addition, in the range of 2~300 K, this complex displays diamagnetic property.
基金Supported by NNSFC(21272167 and 21201127)the Priority Academic Program Development of Jiangsu Higher Education Institution,Graduate Education Innovation Project in Jiangsu Province(CXZZ12_0808 and CXLX12_0784)KLSLRC(KLSLRC-KF-13-HX-1)
文摘The employment of N-hydroxy-pyridine-2-carboxamidine in the coordination chemistry of zinc(II), nickel(II) and manganese(II) under solvothermal conditions is reported. Four complexes of compositions, [Zn2(O2CMe)3{(py)C(NH2)NOH}4](OH) (1), [Zn4(OH)2{(py)C(NH2)- NO}4CI2]'3MeCN (2), [Ni(SO4)(H20){(py)C(NH2)NOH}2]'H2O (3) and [Mn(SO4){(py)C(NH2)- NOH}2]n (4), have been synthesized by rationally choosing different metal salts and dexterously employing acetate and sulfate ions as the bridging groups. Luminescent properties for 2 suggested strong emission in the solid state at room temperature. Variable temperature (2.0-300 K) magnetic studies for the linear chain complex 4 indicate weak antiferromagnetic Mn(Ⅱ)...Mn(Ⅱ) exchange interactions.
基金Funded by National Science Fund for Distinguished Young Scholars (No.50925103)the Key Project of Chinese Ministry of Education (No. 309027)+1 种基金the Fund for Academic Newcomer of PhD of Lanzhou Universitythe National Natural Science Foundation of China(No.11034004)
文摘CuFe2O4 nanotube arrays with different outer diameters were synthesized in anodic aluminum oxide templates through sol-gel techniques followed by heating treatment processes. The morphology of the nanotube arrays was investigated by field emission scanning electron microscope and transmission electron microscopy, suggesting that the nanotube arrays are ordered and uniform. The X-ray diffraction results indicate that the crystal structure of the nanotube arrays is polycrystalline with a spinel-type structure. The measurements of magnetic properties indicate that CuFe2O4 nanotube arrays with outer diameter of 200 nm exhibit magnetic anisotropy with easy magnetization direction along the axis of nanotubes.