40 6 2012 6 ZnO SnO 2 Ta 2 O 5 ZnO JOURNAL OF THE CHINESE CERAMIC SOCIETY 821 Vol. 40 No. 6 June 2012 α-fe/bafe 12 O 19 1 1 1 1 2 (1. 212013 2. 212000) α-fe/bafe 12 O 19 X 375 1 h α-fe/bafe 12 O 19 58.04 A m 2 /kg 32.54 ka/m 24.6 Am 2 /kg α- TQ171 A 0454 5648(2012)06 0821 05 2012 05 23 14:37:07 http://www.cnki.net/kcms/detail/11.2310.tq.20120523.1437.008.html Preparation and Magnetic Properties of α-fe/bafe 12 O 19 Composite Powders via Organic Gel Thermal Reduction Process YANG Xinchun 1 SHEN Xiangqian 1 SONG Fuzhan 1 LIU Ruijiang 1 CUI Xuewen 2 (1. Institute for Advanced Materials, Jiangsu University, Zhenjiang 212013, Jiangsu, China; 2. Affiliated Hospital of Jiangsu University, Zhenjiang 212000, Jiangsu, China) Abstract: The soft/hard α-fe/bafe 12 O 19 composites were prepared by an organic gel thermal reduction process with citric acid and metal salts as starting reagents. The phase, morphology and magnetic properties of the resultant products were analyzed by X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer, respectively. The results showed that the magnetic properties was affected by the phase constituent and reduction process. The saturation magnetization of the α-fe/bafe 12 O 19 composites increased, and the coercivity firstly decreased and then increased with increasing the reduction temperature and time. The composites prepared in H 2 N 2 atmosphere at 375 for 1 h have the specific saturation magnetization of 58.04 A m 2 /kg, coercivity of 32.54 ka/m and specific remanence of 24.6 Am 2 /kg, respectively. Key words: composite powder; α-iron; barium ferrite; organic gel thermal reduction process; magnetic property 1991 Kneller [1] [2 4] [5] [6] [7] [8] [9] Bercoff [5] Fe/BaFe 12 O 19 ( 1 300 K) Liu [9] 2012 01 12 2012 03 09 (20103227110006) (BK2010334) (1987 ) (1959 ) Received date: 2012 01 12. Revised date: 2012 03 09. First author: YANG Xinchun (1987 ), male, Master. E-mail: yhuaze@163.com Correspondent author: SHEN Xiangqian (1959 ), male, professor. E-mail: shenxq@ujs.edu.cn
822 2012 α-fe/z Ba [10 13] / α-fe/bafe 12 O 19 1 1.1 α-fe/bafe 12 O 19 α-fe/bafe 12 O 19 [12] (BaCO 3 ) [Fe(NO 3 ) 3 9H 2 O] (C 6 H 8 O 7 H 2 O) (Fe 2 O 3 BaFe 12 O 19 1:1) 24 h 70 100 50 h 900 2 h α-fe 2 O 3 /BaFe 12 O 19 α-fe 2 O 3 /BaFe 12 O 19 ( 1.0 L/min 5:4) α-fe/bafe 12 O 19 1.2 D/max-rA X [Cu K α λ = 0.154 nm 10 ma 50 kv 8( )/min 0.01( )/min] JEOL JSM-7001F (SEM) HH-15 (vibrating sample magnetometer VSM) 2 2.1 1 α-fe 2 O 3 /BaFe 12 O 19 350 500 1 h X (XRD) 1 350 1 h α-fe α-fe BaFe 12 O 19 α-fe 2 O 3 [14 15] 1 α-fe 2 O 3 /BaFe 12 O 19 1 h XRD Fig. 1 XRD patterns of α-fe 2 O 3 /BaFe 12 O 19 composite precursor after reduction at different temperatures for 1 h α-fe 2 O 3 BaFe 12 O 19 α-fe BaFe 12 O 19 α-fe 2 α-fe 2 O 3 /BaFe 12 O 19 375 XRD 2 375 45 min α-fe 2 O 3 BaFe 12 O 19 α-fe α-fe α-fe 2 O 3 BaFe 12 O 19 2 α-fe 2 O 3 /BaFe 12 O 19 375 XRD Fig. 2 XRD patterns of α-fe 2 O 3 /BaFe 12 O 19 composite precursor after reduction at temperature of 375 for different time
α-fe/bafe 12 O 19 823 α-fe BaFe 12 O 19 1 Scherrer BaFe 12 O 19 α-fe 1 BaFe 12 O 19 α-fe 1 Table 1 α-fe BaFe 12 O 19 Grain size (D) of α-fe and BaFe 12 O 19 at different reduction conditions Reduction condition Phase constituent D (α Fe) /nm D (BaFe12O 19)/nm 375 /30 min BaFe 12 O 19, Fe 2 O 3 34 375 /45 min BaFe 12 O 19, α-fe 30 20 375 /1 h BaFe 12 O 19, α-fe 30 19 400 /1 h BaFe 12 O 19, α-fe 40 13 500 /1 h BaFe 12 O 19, α-fe 44 12 2 α-fe/bafe 12 O 19 375 30 min α-fe 2 O 3 α-fe 2 O 3 α-fe BaFe 12 O 19 α-fe 2 O 3 α-fe BaFe 12 O 19 α-fe 375 1 h 2 Table 2 α-fe/bafe 12 O 19 Chemical compositions in α-fe/bafe 12 O 19 composites at different reduction conditions Reduction condition w(α-fe)/ % w(bafe 12 O 19 )/ % w(α-fe 2 O 3 )/ % 375 /30 min 13.1 42.7 44.2 375 /45 min 37.6 38.9 23.5 375 /1 h 68.1 20.2 11.7 400 /1 h 85.6 14.4 500 /1 h 88.7 11.3 w(α-fe) represents mass fraction of (α-fe), other with this. 2.2 3 375 1 h α-fe BaFe 12 O 19 α-fe/bafe 12 O 19 SEM 3a α-fe 2 O 3 α-fe 200 300 nm 3b BaFe 12 O 19 3c 375 3 α-fe BaFe 12 O 19 α-fe/bafe 12 O 19 375 1 h SEM Fig. 3 SEM morphologies of α-fe, BaFe 12 O 19 and α-fe/ BaFe 12 O 19 composite precursor after reduction at 375 for 1 h 1 h α-fe/bafe 12 O 19 SEM 3c α-fe 2 O 3 ( 3a) BaFe 12 O 19 ( 3b) 3c α-fe BaFe 12 O 19 BaFe 12 O 19 [2]
824 2012 2.3 3 α-fe/bafe 12 O 19 3 (M s ) (H c ) (M r ) M S α-fe H c M r 3 α-fe/bafe 12 O 19 Table 3 Magnetic properties of α-fe/bafe 12 O 19 composites at different reduction conditions Reduction condition M s /(A m 2 kg 1 ) M r /(A m 2 kg 1 ) H c /(ka m 1 ) 350 /1 h 38.5 17.3 72.6 375 /30 min 33.9 14.2 57.5 375 /45 min 40.2 10.8 26.2 375 /1 h 58.1 24.6 32.5 400 /1 h 100.1 19.7 22.3 450 /1 h 128.7 17.2 14.4 M s Specific saturation magnetization; M r Specific remanence; H c Coercivity. 4 α-fe 2 O 3 /BaFe 12 O 19 375 30 min 1 h α-fe 2 O 3 BaFe 12 O 19 375 1 h 4 375 30 min 1 α-fe obtained at 375 for 1 h; 2, 4 α-fe/bafe 12 O 19 composites obtained at 375 for 1 h and 30 min, respectively; 3 BaFe 12 O 19 obtained at 375 for 1 h. 4 α-fe BaFe 12 O 19 α-fe/bafe 12 O 19 Fig. 4 Hysteresis loops of α-fe, BaFe 12 O 19 and α-fe/bafe 12 O 19 composites α-fe 2 O 3 375 1 h M s = 58.1A m 2 /kg H c = 32.5 ka/m M r = 24.5 A m 2 /kg α-fe BaFe 12 O 19 4 4 α-fe/bafe 12 O 19 M S H C α-fe BaFe 12 O 19 M r α-fe BaFe 12 O 19 M r [2] Table 4 4 Magnetic properties of different powders Powder M s /(A m 2 kg 1 ) M r /(A m 2 kg 1 ) H c /(ka m 1 ) α-fe 89.3 16.4 26.7 α-fe/bafe 12 O 19 58.1 24.6 32.5 BaFe 12 O 19 46.4 22.2 116.6 (α-fe) (BaFe 12 O 19 ) 3 [2,12] BaFe 12 O 19 α-fe BaFe 12 O 19 α-fe α-fe α-fe BaFe 12 O 19 α-fe/bafe 12 O 19 3 1) α-fe/bafe 12 O 19
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