The soft magnetic properties and giant magnetoimpedance(GMI) effect of the multilayered structure(F/SiO2)3/Ag/(SiO2/F)3(F≡Fe71.5Cu1Cr2.5V4Si12B9) films,which were prepared by radio frequency sputtering without and wi...The soft magnetic properties and giant magnetoimpedance(GMI) effect of the multilayered structure(F/SiO2)3/Ag/(SiO2/F)3(F≡Fe71.5Cu1Cr2.5V4Si12B9) films,which were prepared by radio frequency sputtering without and with a longitudinal magnetic field of about 72 kA/m,are studied.The results show that the GMI effect almost cannot be detected in the samples deposited without field,whereas,a longitudinal magnetic field applied during deposition process obviously optimizes the soft magnetic properties of the films,and noticeable GMI effect is obtained.The maximum values of the longitudinal and transverse GMI ratios are 45% and 44% at the frequency of 6.81 MHz,respectively.In addition,the dependence of magnetoimpedance ratio,magnetoresistance ratio,magnetoreactance ratio and effective permeability ratio on the frequency has been investigated.We found that the GMI spectrum curves in the longitudinal and transverse cases almost overlap for the field-deposited sample.The GMI effect is mainly a giant magnetoinductive effect at low frequencies.When f 】9 MHz,magnetoreactance ratio changes to a negative,i.e.,the property of reactance changes from inductive to capacitive.展开更多
Effects of the wheel speeds v and disproportionation time during the SC-HDDR process on the properties of Nd-Fe-B magnetic powders are investigated.It is found that the remanence Br,coercivity Hcj and energy products(...Effects of the wheel speeds v and disproportionation time during the SC-HDDR process on the properties of Nd-Fe-B magnetic powders are investigated.It is found that the remanence Br,coercivity Hcj and energy products(BH)max of magnetic powders all first increase to the maximum at v=3 m/s,and then decrease with enhancing v.This is attributed to the fact that the SC alloy flakes prepared by the wheel speed of 3 m/s display the optimized microstructure.This optimized SC alloy flakes without homogenizing treatment which carried out a short duration disproportionation treatment can prepare the evidently anisotropic powders.With prolonging disproportionation time,the alignment degree of anisotropy of magnetic powders gradually decreases.This is due to the fact that a short duration disproportionation reaction is beneficial to the disproportionated microstructure displaying the lamella crystals,and the lamella disproportionated microstructure is helpful to the formation of anisotropy.Our results confirm that the anisotropic HDDR Nd-Fe-B magnetic powders prepared directly from the SC alloy flakes without homogenizing treatment can be obtained.展开更多
基金supported by the Science and Technology Key Project of Zhejiang Province,China (Grant No.2006C21085)the Xinmiao Project of Zhejiang Province,China (Grant No.2007R40G2170041)
文摘The soft magnetic properties and giant magnetoimpedance(GMI) effect of the multilayered structure(F/SiO2)3/Ag/(SiO2/F)3(F≡Fe71.5Cu1Cr2.5V4Si12B9) films,which were prepared by radio frequency sputtering without and with a longitudinal magnetic field of about 72 kA/m,are studied.The results show that the GMI effect almost cannot be detected in the samples deposited without field,whereas,a longitudinal magnetic field applied during deposition process obviously optimizes the soft magnetic properties of the films,and noticeable GMI effect is obtained.The maximum values of the longitudinal and transverse GMI ratios are 45% and 44% at the frequency of 6.81 MHz,respectively.In addition,the dependence of magnetoimpedance ratio,magnetoresistance ratio,magnetoreactance ratio and effective permeability ratio on the frequency has been investigated.We found that the GMI spectrum curves in the longitudinal and transverse cases almost overlap for the field-deposited sample.The GMI effect is mainly a giant magnetoinductive effect at low frequencies.When f 】9 MHz,magnetoreactance ratio changes to a negative,i.e.,the property of reactance changes from inductive to capacitive.
基金supported by the National Natural Science Foundation of China (Grant Nos 50671055 and 50801043)
文摘Effects of the wheel speeds v and disproportionation time during the SC-HDDR process on the properties of Nd-Fe-B magnetic powders are investigated.It is found that the remanence Br,coercivity Hcj and energy products(BH)max of magnetic powders all first increase to the maximum at v=3 m/s,and then decrease with enhancing v.This is attributed to the fact that the SC alloy flakes prepared by the wheel speed of 3 m/s display the optimized microstructure.This optimized SC alloy flakes without homogenizing treatment which carried out a short duration disproportionation treatment can prepare the evidently anisotropic powders.With prolonging disproportionation time,the alignment degree of anisotropy of magnetic powders gradually decreases.This is due to the fact that a short duration disproportionation reaction is beneficial to the disproportionated microstructure displaying the lamella crystals,and the lamella disproportionated microstructure is helpful to the formation of anisotropy.Our results confirm that the anisotropic HDDR Nd-Fe-B magnetic powders prepared directly from the SC alloy flakes without homogenizing treatment can be obtained.
