LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）Hxalloys were prepared by hydrogenation.Samples were annealed at 1343Kfor30-90 hto form the NaZn13 phase.La-rich andα-Fe secondary phases were also detected.Saturated hydr...LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）Hxalloys were prepared by hydrogenation.Samples were annealed at 1343Kfor30-90 hto form the NaZn13 phase.La-rich andα-Fe secondary phases were also detected.Saturated hydrogenation at 553 Kand 0.15 MPa of H_2 pressure for 5hwas employed to improve the Curie temperature of the alloys to 279 K.The maximum magnetic entropy change,relative cooling power,and adiabatic temperature change of LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x annealed at 1343 Kfor 90hafter hydrogen absorption are 6.38J/（kg·K）（magnetic changesμ0ΔH =1.65T）,100.1J/kg（μ0ΔH =1.65T）,and 2.2 K（μ0ΔH =1.48T）,respectively.Although the maximum magnetic entropy change of the LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x alloys is lower than those of similar alloys with high purity raw materials,the relative cooling power is nearly the same.The effect of impurities of the raw materials used was also discussed.It is assumed that the impurity of 0.2wt.% Al is responsible for the reduced entropy change of the resulted alloys.The LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x alloys prepared by this method could be a low cost alternative material for room temperature magnetic cooling applications.展开更多
High-precision detection of microwave field information is important in the fields of space wireless communication,space microwave remote sensing,and satellite navigation.In this paper,the high-precision detection of ...High-precision detection of microwave field information is important in the fields of space wireless communication,space microwave remote sensing,and satellite navigation.In this paper,the high-precision detection of broadband microwave is realized.High-precision detection of microwave fields has been realized for the first time based on the spin-mixing model of nitrogen-vacancy color centers and the continuous wave optically detected magnetic resonance(ODMR)process.By changing the power ratio between the signal and reference microwave fields,the validity of high-precision detection of microwaves is verified,and the microwave magnetic field detection resolution is less than 100 nW and the Pearson correlation coefficient of the system’s response to microwave intensity is 0.9974.Then,by optimizing the data acquisition time,the megahertz-level frequency resolution of the signal microwave is achieved.In addition,the gigahertz bandwidth and megahertz resolution were also verified by tuning the resonance frequency of the spin energy level to an external static magnetic field.These results provide an important technological basis for solid-state microwave receivers based on nitrogen-vacancy color centers,highprecision spectral resolution detection,and microwave sensing.展开更多
基金financially supported by Inner Mongolia Natural Science Foundation of China(2013MS0802)
文摘LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）Hxalloys were prepared by hydrogenation.Samples were annealed at 1343Kfor30-90 hto form the NaZn13 phase.La-rich andα-Fe secondary phases were also detected.Saturated hydrogenation at 553 Kand 0.15 MPa of H_2 pressure for 5hwas employed to improve the Curie temperature of the alloys to 279 K.The maximum magnetic entropy change,relative cooling power,and adiabatic temperature change of LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x annealed at 1343 Kfor 90hafter hydrogen absorption are 6.38J/（kg·K）（magnetic changesμ0ΔH =1.65T）,100.1J/kg（μ0ΔH =1.65T）,and 2.2 K（μ0ΔH =1.48T）,respectively.Although the maximum magnetic entropy change of the LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x alloys is lower than those of similar alloys with high purity raw materials,the relative cooling power is nearly the same.The effect of impurities of the raw materials used was also discussed.It is assumed that the impurity of 0.2wt.% Al is responsible for the reduced entropy change of the resulted alloys.The LaFe_（11.39）Mn_（0.35）Si_（1.26）B_（0.1）H_x alloys prepared by this method could be a low cost alternative material for room temperature magnetic cooling applications.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U21A20141)the National Natural Science Foundation of China(52435011,62103385,62175219).
文摘High-precision detection of microwave field information is important in the fields of space wireless communication,space microwave remote sensing,and satellite navigation.In this paper,the high-precision detection of broadband microwave is realized.High-precision detection of microwave fields has been realized for the first time based on the spin-mixing model of nitrogen-vacancy color centers and the continuous wave optically detected magnetic resonance(ODMR)process.By changing the power ratio between the signal and reference microwave fields,the validity of high-precision detection of microwaves is verified,and the microwave magnetic field detection resolution is less than 100 nW and the Pearson correlation coefficient of the system’s response to microwave intensity is 0.9974.Then,by optimizing the data acquisition time,the megahertz-level frequency resolution of the signal microwave is achieved.In addition,the gigahertz bandwidth and megahertz resolution were also verified by tuning the resonance frequency of the spin energy level to an external static magnetic field.These results provide an important technological basis for solid-state microwave receivers based on nitrogen-vacancy color centers,highprecision spectral resolution detection,and microwave sensing.
