Due to the hydrogen embrittlement effect,La(Fe,Si)_(13)-based hydrides can only exist in powder form,which limits their practical application.In this work,ductile and thermally conductive Al metal was homogeneously mi...Due to the hydrogen embrittlement effect,La(Fe,Si)_(13)-based hydrides can only exist in powder form,which limits their practical application.In this work,ductile and thermally conductive Al metal was homogeneously mixed with La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)using the ball milling method.Then hydrogenation and compactness shaping of the magnetocaloric composites were performed in one step via a sintering process under high hydrogen pressure.As the Al content reached 9 wt.%,the La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)H_(y)/Al composite showed the mechanical behavior of a ductile material with a yield strength of~44 MPa and an ultimate strength of 269 MPa accompanied by a pronounced improvement in thermal conductivity.Due to the ease of formation of Fe-Al-Si phases and the several micron and submicron sizes of the composite particles caused by ball milling process,the magnetic entropy change of the composites was substantially reduced to~1.2 J/kg·K-1.5 J/kg·K at 0 T-1.5 T.展开更多
The Curie temperatures(T_(C))of La_(0.7)Ce_(0.3)Fe_(13-x-y)Mn_(x)Si_(y)compounds that are hydrogenated to saturation are raised to near room temperature.The age stability was inves-tigated for the fully hydrogenated L...The Curie temperatures(T_(C))of La_(0.7)Ce_(0.3)Fe_(13-x-y)Mn_(x)Si_(y)compounds that are hydrogenated to saturation are raised to near room temperature.The age stability was inves-tigated for the fully hydrogenated La_(0.7)Ce_(0.3)Fe_(11.5-x)Mn_(x)Si_(1.5) compounds.This result indicates that the H content will slowly decrease in the hydrides,leading to a decrease in T_(C).However,no age splitting is observed after the hydrides are held at room temperature for two years,indicating the excellent age stability of the hydrides.Further structural analysis by neutron diffrac-tion shows that Mn atoms preferentially substitute Fe in the 96i sites.The T_(C)of La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides can be adjusted to the desired working temperature by regulating Mn content based on the linear relationship between T_(C)and Mn content.Moreover,the La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides exhibit a giant magnetic entropy change of 15 J·kg^(-1)·K^(-1) under a low magneticfield change of 0-1 T.As a result,the giant magnetocaloric effect,linearly adjustable T_(C),and excel-lent age stability make the La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides be one of the ideal candidates for room temperature magnetic refrigerants.展开更多
Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous...Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.展开更多
基金Project supported by the Open Research Project of State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilizationthe National Natural Science Foundation of China(Grant Nos.51771197 and 52171187)。
文摘Due to the hydrogen embrittlement effect,La(Fe,Si)_(13)-based hydrides can only exist in powder form,which limits their practical application.In this work,ductile and thermally conductive Al metal was homogeneously mixed with La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)using the ball milling method.Then hydrogenation and compactness shaping of the magnetocaloric composites were performed in one step via a sintering process under high hydrogen pressure.As the Al content reached 9 wt.%,the La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)B_(0.2)H_(y)/Al composite showed the mechanical behavior of a ductile material with a yield strength of~44 MPa and an ultimate strength of 269 MPa accompanied by a pronounced improvement in thermal conductivity.Due to the ease of formation of Fe-Al-Si phases and the several micron and submicron sizes of the composite particles caused by ball milling process,the magnetic entropy change of the composites was substantially reduced to~1.2 J/kg·K-1.5 J/kg·K at 0 T-1.5 T.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFB0702704)the National Science Foundation of China (No. 51571018)。
文摘The Curie temperatures(T_(C))of La_(0.7)Ce_(0.3)Fe_(13-x-y)Mn_(x)Si_(y)compounds that are hydrogenated to saturation are raised to near room temperature.The age stability was inves-tigated for the fully hydrogenated La_(0.7)Ce_(0.3)Fe_(11.5-x)Mn_(x)Si_(1.5) compounds.This result indicates that the H content will slowly decrease in the hydrides,leading to a decrease in T_(C).However,no age splitting is observed after the hydrides are held at room temperature for two years,indicating the excellent age stability of the hydrides.Further structural analysis by neutron diffrac-tion shows that Mn atoms preferentially substitute Fe in the 96i sites.The T_(C)of La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides can be adjusted to the desired working temperature by regulating Mn content based on the linear relationship between T_(C)and Mn content.Moreover,the La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides exhibit a giant magnetic entropy change of 15 J·kg^(-1)·K^(-1) under a low magneticfield change of 0-1 T.As a result,the giant magnetocaloric effect,linearly adjustable T_(C),and excel-lent age stability make the La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides be one of the ideal candidates for room temperature magnetic refrigerants.
基金This work was supported by National Natural Science Foundation of China(Nos.11834012,51620105014,91963207,91963122,51902237)National Key R&D Program of China(No.2018YFB0703603,2019YFA0704900,SQ2018YFE010905)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT 2020e004).EPMA experiments were performed at the Center for Materials Research and Testing of Wuhan University of Technology.The S/TEM work was performed at the Nanostructure Research Center(NRC),which is supported by the Fundamental Research Funds for the Central Universities(WUT:2019III012GX).
文摘Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.
