納米復(fù)合材料外文翻譯--鋇鐵氧體納米復(fù)合材料的電磁微波

1、<p>　　1800單詞，1萬英文字符，中文2840字</p><p>　　出處：Liu J R, Itoh M, Machida K. Magnetic and electromagnetic wave absorption properties of α-Fe∕ Z-type Ba-ferrite nanocomposites[J]. Applied Physics Letters, 2006, 8

2、8(6): 062503.</p><p><b>　　原文</b></p><p>　　Magnetic and electromagnetic wave absorption properties of -Fe/Z-type Ba-ferrite nanocomposites</p><p>　　Jiu Rong Liu, Masahiro

3、 Itoh, and Ken-ichi Machidaa</p><p>　　Center for Advanced Science and Innovation, Osaka University, 2-1 Yamadaoka</p><p>　　Suita, Osaka565-0871, Japan</p><p>　　(Received 16 August 2

4、005; accepted 6 December 2005; published online 7 February 2006)</p><p>　　The saturation magnetization values (Ms) of -Fe / Ba3Co1.8Fe23.6Cr0.6O41 nanocomposites prepared by mechanically alloying-Fe with Ba3

5、Co1.8Fe23.6Cr0.6O41 powders increased with increasing the concentration of-Fe.-Fe / Ba3Co1.8Fe23.6Cr0.6O41 nanocomposites showed higher coercivity values than а-Fe and Ba3Co1.8Fe23.6Cr0.6O41 because of the effects of sh

6、ape anisotropy and exchange bias. The resin compacts with 33.5 vol% -Fe/Ba3Co1.8Fe23.6Cr0.6O41 (38, 70, 85 vol% а-Fe) powders provided good electro</p><p>　　Ferrites, as conventional electromagnetic (EM) wav

7、e absorbing materials, have been widely studied from megahertz to igahertz (GHz) range because of their strong magnetism and high electric resistivity[1–3]. For EM wave applications there is an increasing interest in usi

8、ng ferrite-polymer ?lms rather than bulk ferrites. But, the thickness of ferrite-polymer ?lms has to be thick for ef?cient EM wave absorption, since it is dif?cult to increase the permeability values in GHz range owing t

9、o Snoek’s </p><p>　　Ba3Co1.8Fe23.6Cr0.6O41 was prepared by a conventional solid-state reaction method from the starting materials of BaCO3, Co3O4,Cr2O3, and Fe2O3 powders (purity 99 %)[12].-Fe/ Ba3Co1.8Fe23.

10、6Cr0.6O41(38, 70, 85 vol%-Fe) nanocomposites were obtained by ball-milling Ba3Co1.8Fe23.6Cr0.6O41 (<100 μm) with -Fe powders (325 mesh) in hexane, respectively. After drying at 623 K for 2 h in Ar, the resultant powde

11、rs were characterized by x-ray diffraction (XRD), and the microstructures were analyzed by a hig</p><p><b>　?。?）</b></p><p><b>　　（2）</b></p><p>　　where f is

12、 the frequency of the electromagnetic wave, d is the thickness of an absorber, c is the velocity of light, Z0 is the impedance of free space, and Zin is the input impedance of absorber. The RL value of ?20 dB is comparab

13、le to the 99% of EM wave absorption according to Eqs. (1) and (2), and thus “RL<?20 dB” is considered as an adequate EM absorption.</p><p>　　FIG.1. XRD patterns of（a）-Fe,（b） Ba3Co1.8Fe23.6Cr0.6O41,and（c）,

14、（d）,（e）-Fe/ Ba3Co1.8Fe23.6Cr0.6O41 nanocomposite powders with 38, 70, or 85 vol % -Fe, respectively.</p><p>　　Figure 1 shows the typical XRD patterns measured on the-Fe, Ba3Co1.8Fe23.6Cr0.6O41, and -Fe/Ba3Co

15、1.8Fe23.6Cr0.6O41 powders. From Fig.1(b), it was found that Ba3Co1.8Fe23.6Cr0.6O41 compound was formed by the solid-state reaction. All the peaks could be indexed as the hexagonal lattice of Ba3Co1.8Fe23.6Cr0.6O41 (JCPDS

16、 19-97). After ball milling the mixture of -Fe with Ba3Co1.8Fe23.6Cr0.6O41 powders at 200 r/min for 30 h in hexane and subsequent drying, only the peaks of -Fe were observed. The peak</p><p>　　FIG. 2. Freque

17、ncy dependences of relative permittivity εr(a), real part (b), and imaginary part (c) of relative permeability for the resin composites with 33.5 vol% of -Fe, Ba3Co1.8Fe23.6Cr0.6O41, and -Fe/Ba3Co1.8Fe23.6Cr0.6O41(38, 7

18、0, or 85 vol% -Fe)nanocomposite powders, respectively.</p><p>　　Figure 2(a) shows that the real part () and the imaginary part () of relative permittivity for the resin composites with 33.5 vol% -Fe/Ba3Co1.8

19、Fe23.6Cr0.6O41 powders containing 38, 70, or 85 vol% -Fe were almost constant between 2 and 18 GHz, for which the relative permittivity () showed less variation (=10,10,11 and =0.4, 0.4, 0.5, respectively). For the resin

20、 composites with 33.5 vol% Ba3Co1.8Fe23.6Cr0.6O41 powders, the and values were low constant and almost independent of frequency in the </p><p>　　FIG. 3. Frequency dependences of RL for the resin composites

21、 with 33.5 vol% of(a) Ba3Co1.8Fe23.6Cr0.6O41, and（b）-Fe/Ba3Co1.8Fe23.6Cr0.6O41（70 vol % -Fe）powders</p><p>　　Figure 3(a) shows the typical relationship between RL and frequency for the resin composites with

22、33.5 vol% Ba3Co1.8Fe23.6Cr0.6O41 powders. The RL values less than ?20 dB were obtained in the 4.6-12.4 GHz with absorber thickness of 2.8-5.4 mm. For the resin composites with 33.5 vol% -Fe/Ba3Co1.8Fe23.6Cr0.6O41（70 vol%

23、 -Fe）powders, the RL values less than ?20 dB were recorded in the 5.4-10.5 GHz with absorber thickness of 1.6-3.0 mm. In particular, a minimum RL of ?51 dB was obtained at 7.0 GHz wi</p><p>　　In conclusion,

24、-Fe/Ba3Co1.8Fe23.6Cr0.6O41(38, 70, or 85 vol%-Fe) nanocomposites have been prepared by ball-milling-Fe with Ba3Co1.8Fe23.6Cr0.6O41 powders, respectively, of which Ba3Co1.8Fe23.6Cr0.6O41 plays the double roles as magnet a

25、nd insulator for suppressing the eddy current loss. -Fe/Ba3Co1.8Fe23.6Cr0.6O41 nanocomposites showed higher Hc values than -Fe and Ba3Co1.8Fe23.6Cr0.6O41. Comparing with ferrites, -Fe / Ba3Co1.8Fe23.6Cr0.6O41 nanocomposi

26、tes with 70 or 85 vol% -Fe are promising for </p><p>　　This work was supported by Grant-in-Aid for Scienti?c Research No. 15205025 from the Ministry of Education, Science, Sports, and Culture of Japan, and I

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