Combined with the rough textures which are usually used for fabricating the planar solar cells, textured-microwire（MW） structures（there are MW textures on the tops of MWs） are fabricated. Both simulative and exper...Combined with the rough textures which are usually used for fabricating the planar solar cells, textured-microwire（MW） structures（there are MW textures on the tops of MWs） are fabricated. Both simulative and experimental investigations of the optical properties of Si surface with microwires are carried out and the results show that surfaces of texturedMW structures exhibit lower reflectance in the short wavelength range, but higher reflectance in the long wavelength range than the conventional textured surface. It is also shown, consequently, that the textured-MW structures could absorb more photons in the short wavelength range, which could help improve the performance of the solar cells.展开更多
The Tb-Fe-Cr alloy powders were prepared by the arc melting method and high energy ball milling. The phase structure and the mierostructure of the alloys powders were analyzed by X-ray diffraction （XRD） and scanning...The Tb-Fe-Cr alloy powders were prepared by the arc melting method and high energy ball milling. The phase structure and the mierostructure of the alloys powders were analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and then their mi- crowave absorbing properties were analyzed by Vector network analyzer. The results showed that the absorption peak values of Tb9FessCr3 alloy with a material thickness of 2.0 mm were lower than -16.5 dB when ball milling time was from 50 to 60 h, and the wide frequency of reflectivity under -10 dB were all more than 4 GHz. When the ball milling time was 50 h, the alloy powders had better electromagnetic properties. The absorption peak value of alloy reached -25.8 dB, and the wide frequency of reflectivity under -10 dB reached 4.8 GHz. When the ball milling time was more than 70 h, the alloy powders would become thinner, leading to worse electromagnetic properties of the alloy, the absorption peak shifted towards low frequency under the same material thickness. The TbxFe97_xCr3 （.v=7, 9, 11, 13, 15 mol.%） alloy dealt with 60 h ball milling time had better wide-frequency characteristic under 1.8 mm of material thickness. The absorption peak shifted towards higher frequency region from lower frequency region with increased atom percent of Tb in the alloy, and the inflexion point appeared when x=13. At low frequency, the microwave absorbing properties of Tb11Fe86Cr3 alloy was better than those of the others. The absorption peak value of Tb11Fe82Cr3 alloy was -24 dB, and the wide frequency of reflectivity under -10 dB was 4.5 GHz.展开更多
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
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1332205,11274153,11204124,and 11404091)
文摘Combined with the rough textures which are usually used for fabricating the planar solar cells, textured-microwire（MW） structures（there are MW textures on the tops of MWs） are fabricated. Both simulative and experimental investigations of the optical properties of Si surface with microwires are carried out and the results show that surfaces of texturedMW structures exhibit lower reflectance in the short wavelength range, but higher reflectance in the long wavelength range than the conventional textured surface. It is also shown, consequently, that the textured-MW structures could absorb more photons in the short wavelength range, which could help improve the performance of the solar cells.
基金supported by the National Natural Science Foundation of China (50961005)the Natural Science Foundation of Guangxi (0710908-12-Z, 0991002Z)
文摘The Tb-Fe-Cr alloy powders were prepared by the arc melting method and high energy ball milling. The phase structure and the mierostructure of the alloys powders were analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, and then their mi- crowave absorbing properties were analyzed by Vector network analyzer. The results showed that the absorption peak values of Tb9FessCr3 alloy with a material thickness of 2.0 mm were lower than -16.5 dB when ball milling time was from 50 to 60 h, and the wide frequency of reflectivity under -10 dB were all more than 4 GHz. When the ball milling time was 50 h, the alloy powders had better electromagnetic properties. The absorption peak value of alloy reached -25.8 dB, and the wide frequency of reflectivity under -10 dB reached 4.8 GHz. When the ball milling time was more than 70 h, the alloy powders would become thinner, leading to worse electromagnetic properties of the alloy, the absorption peak shifted towards low frequency under the same material thickness. The TbxFe97_xCr3 （.v=7, 9, 11, 13, 15 mol.%） alloy dealt with 60 h ball milling time had better wide-frequency characteristic under 1.8 mm of material thickness. The absorption peak shifted towards higher frequency region from lower frequency region with increased atom percent of Tb in the alloy, and the inflexion point appeared when x=13. At low frequency, the microwave absorbing properties of Tb11Fe86Cr3 alloy was better than those of the others. The absorption peak value of Tb11Fe82Cr3 alloy was -24 dB, and the wide frequency of reflectivity under -10 dB was 4.5 GHz.
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.
