REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powde...REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powders were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and their microwave absorbing properties were determined by a vector network analyzer. The results show that the alloys with light rare earths （Ce, Pr） have good low frequency absorbing property and those with heavy rare earths （Tb, Er） exhibit an improved high frequency absorbing property. The minimum refleetivity at the absorbing peak frequency of RE,FeuCr3（RE=Ce, Pr, Tb, Er） are -9.49 dB at 5.76 GHz, -22.38 dB at 7.92 GHz, -18.52 dB at 11.68 GHz and -17.59 dB at 10.24 GHz, respectively. The absorbing bandwidth under -10 dB of the Pr13FesaCr3 powder was widened from 1.91 GI-Iz to 3.89 GHz by adding 2% Ti, but the reflectivity of the alloy was increased from -22.38 dB to -14.91 riB.展开更多
采用真空电弧熔炼和高能球磨法制备片状NdxCe2-xCo17合金粉末并且研究了Nd含量和匹配厚度对相组成、形貌、电磁参数和微波吸收性能的影响。结果表明,Nd0.3Ce1.7Co17粉末的最大反射率可以达到-32.36 d B,同时有效带宽能扩大4倍。此外,调...采用真空电弧熔炼和高能球磨法制备片状NdxCe2-xCo17合金粉末并且研究了Nd含量和匹配厚度对相组成、形貌、电磁参数和微波吸收性能的影响。结果表明,Nd0.3Ce1.7Co17粉末的最大反射率可以达到-32.36 d B,同时有效带宽能扩大4倍。此外,调整Nd含量能成功优化Ce2Co17合金粉末的微波吸收性能。随着Nd含量的增加,吸收峰有向低频段移动的趋势,并且当厚度为1.8mm时,Nd0.3Ce1.7Co17粉末在7.28 GHz处最大反射率可以达到-30.53 d B,并且有效带宽为2.24 GHz中,这表明Nd-Ce-Co合金在C波段是具有低厚度、宽频和高效等特点的理想吸收材料。展开更多
Based on the semi-classical Thomas-Fermi approximation together with the Skyrme energy-density functional, we study the deformation dependence of symmetry energy coefficients of finite nuclei. The symmetry energy coef...Based on the semi-classical Thomas-Fermi approximation together with the Skyrme energy-density functional, we study the deformation dependence of symmetry energy coefficients of finite nuclei. The symmetry energy coefficients of nuclei with mass number A = 40, 100, 150, 208 are extracted from two-parameter parabola fitting to the calculated energy per particle. We find that the symmetry energy coefficients decrease with the increase of nuclear quadrupole deformations, which is mainly due to the isospin dependence of the difference between the proton and neutron surface diffuseness. Large deformations of nuclei can cause the change of the symmetry energy coefficient by about 0.5 Me V and the influence of nuclear deformations on the symmetry energy coefficients is more evident for light and intermediate nuclei.展开更多
基金Funded by National Natural Science Foundation of China(Nos.50961005 and 51361007)National Natural Science Foundation of Guangxi(Nos.2012 GXNSFGA06002 and 2013GXNSFAA019295)
文摘REI3Fes4Cr3（RE=Ce, Pr, Tb, Er） and Pr13_XFes4Cr3Ti（x=0, 2, 4, 6） alloy powders were prepared by are smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powders were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and their microwave absorbing properties were determined by a vector network analyzer. The results show that the alloys with light rare earths （Ce, Pr） have good low frequency absorbing property and those with heavy rare earths （Tb, Er） exhibit an improved high frequency absorbing property. The minimum refleetivity at the absorbing peak frequency of RE,FeuCr3（RE=Ce, Pr, Tb, Er） are -9.49 dB at 5.76 GHz, -22.38 dB at 7.92 GHz, -18.52 dB at 11.68 GHz and -17.59 dB at 10.24 GHz, respectively. The absorbing bandwidth under -10 dB of the Pr13FesaCr3 powder was widened from 1.91 GI-Iz to 3.89 GHz by adding 2% Ti, but the reflectivity of the alloy was increased from -22.38 dB to -14.91 riB.
基金National Natural Science Foundation of China(51361007)Guangxi Natural Science Foundation(2014GXNSFAA118317)+2 种基金Scientific Research Project of Guangxi Education Department(YB2014139)Innovation Project of GUET Graduate Education(YJCXS 201566)Guangxi Key Laboratory of Information Materials(131010-Z)
基金National Natural Science Foundation of China(51361007)Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing(GXKL06170107)Innovation Project of GUET Graduate Education(2018YJCX87)
文摘采用真空电弧熔炼和高能球磨法制备片状NdxCe2-xCo17合金粉末并且研究了Nd含量和匹配厚度对相组成、形貌、电磁参数和微波吸收性能的影响。结果表明,Nd0.3Ce1.7Co17粉末的最大反射率可以达到-32.36 d B,同时有效带宽能扩大4倍。此外,调整Nd含量能成功优化Ce2Co17合金粉末的微波吸收性能。随着Nd含量的增加,吸收峰有向低频段移动的趋势,并且当厚度为1.8mm时,Nd0.3Ce1.7Co17粉末在7.28 GHz处最大反射率可以达到-30.53 d B,并且有效带宽为2.24 GHz中,这表明Nd-Ce-Co合金在C波段是具有低厚度、宽频和高效等特点的理想吸收材料。
基金National Natural Science Foundation of China(51361007)Guangxi Natural Science Foundation(2014GXNSFAA118317)+1 种基金Scientific Research Project of Guangxi Education Department(YB2014139)Guangxi Key Laboratory of Information Materials(131010-Z)
基金National Natural Science Foundation of China (51361007)2017 Director Fund of Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing (GXKL06170107)+1 种基金Guangxi Key Laboratory of Information Materials (171016-Z)Innovation Project of GUET Graduate Education (2018YJCX87, 2019YCXS116)。
基金supported by the National Natural Science Foundation of China(Grants Nos.11275052,11365005 and 11422548)
文摘Based on the semi-classical Thomas-Fermi approximation together with the Skyrme energy-density functional, we study the deformation dependence of symmetry energy coefficients of finite nuclei. The symmetry energy coefficients of nuclei with mass number A = 40, 100, 150, 208 are extracted from two-parameter parabola fitting to the calculated energy per particle. We find that the symmetry energy coefficients decrease with the increase of nuclear quadrupole deformations, which is mainly due to the isospin dependence of the difference between the proton and neutron surface diffuseness. Large deformations of nuclei can cause the change of the symmetry energy coefficient by about 0.5 Me V and the influence of nuclear deformations on the symmetry energy coefficients is more evident for light and intermediate nuclei.
