We propose a hybrid coercivity mechanism for exchange-coupled hard/soft multilayers, which incorporates elements of both the traditional nucleation and pinning mechanisms based on both threedimensional(3 D) and one-di...We propose a hybrid coercivity mechanism for exchange-coupled hard/soft multilayers, which incorporates elements of both the traditional nucleation and pinning mechanisms based on both threedimensional(3 D) and one-dimensional(1 D) micromagnetic calculations. The magnetic reversal starts with the nucleation of the domain wall near the defects or soft phases, which ends by the pinning usually in the same place. Therefore, pinning near the nucleation centers are the dominant coercivity mechanism for both exchange-coupled nanocomposites and so-called single-phased permanent magnets. Our proposed coercivity mechanism and calculated results agree very well with available experimental data,especially the recently reported high energy products achieved in NdFeB and SmCo based hard/soft multilayers. The hybrid coercivity mechanism can be readily extended to single-phased permanent magnets with defects and other magnetic systems.展开更多
By taking the functional adva ntages of both pyrazolate and carboxylate ligands,a unique dual-functional pyrazolate-carboxylate ligand acid,4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid(H3PCBA) was designed and...By taking the functional adva ntages of both pyrazolate and carboxylate ligands,a unique dual-functional pyrazolate-carboxylate ligand acid,4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid(H3PCBA) was designed and synthesized.Using it,a new Co(Ⅱ)-based metal-organic framework(MOF),Co_(3)(PCBA)_(2)(H_(2)O)_(2)(BUT-75) has been constructed.It revealed a(3,6)-connected net based on the 6-connected linear trinuclear metal node,and showed good chemical stability in a wide pH range from 3 to 12 at room temperature,as well as in boiling water.Due to the presence of rich exposed Co(Ⅱ) sites in pores,BUT-75 presented high selective CO_(2) adsorption capacity over N2 at 298 K.Simultaneously,it demonstrated fine catalytic performance for the cycloaddition of CO_(2) with epoxides into cyclic carbonates under ambient conditions.This work has not only enriched the MOF community through integrating diverse functio nalities into one ligand but also contributed a versatile platform for CO_(2) fixation,thereby pushing MOF chemistry forward by stability enhancement and application expansion.展开更多
基金Project supported by National Natural Science Foundation of China(51771127,51571126,51772004)
文摘We propose a hybrid coercivity mechanism for exchange-coupled hard/soft multilayers, which incorporates elements of both the traditional nucleation and pinning mechanisms based on both threedimensional(3 D) and one-dimensional(1 D) micromagnetic calculations. The magnetic reversal starts with the nucleation of the domain wall near the defects or soft phases, which ends by the pinning usually in the same place. Therefore, pinning near the nucleation centers are the dominant coercivity mechanism for both exchange-coupled nanocomposites and so-called single-phased permanent magnets. Our proposed coercivity mechanism and calculated results agree very well with available experimental data,especially the recently reported high energy products achieved in NdFeB and SmCo based hard/soft multilayers. The hybrid coercivity mechanism can be readily extended to single-phased permanent magnets with defects and other magnetic systems.
基金financially supported by the National Natural Science Foundation of China (Nos.21771012,21601008,51621003)the Science & Technology Project of Beijing Municipal Education Committee (No.KZ201810005004)。
文摘By taking the functional adva ntages of both pyrazolate and carboxylate ligands,a unique dual-functional pyrazolate-carboxylate ligand acid,4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid(H3PCBA) was designed and synthesized.Using it,a new Co(Ⅱ)-based metal-organic framework(MOF),Co_(3)(PCBA)_(2)(H_(2)O)_(2)(BUT-75) has been constructed.It revealed a(3,6)-connected net based on the 6-connected linear trinuclear metal node,and showed good chemical stability in a wide pH range from 3 to 12 at room temperature,as well as in boiling water.Due to the presence of rich exposed Co(Ⅱ) sites in pores,BUT-75 presented high selective CO_(2) adsorption capacity over N2 at 298 K.Simultaneously,it demonstrated fine catalytic performance for the cycloaddition of CO_(2) with epoxides into cyclic carbonates under ambient conditions.This work has not only enriched the MOF community through integrating diverse functio nalities into one ligand but also contributed a versatile platform for CO_(2) fixation,thereby pushing MOF chemistry forward by stability enhancement and application expansion.
