Í 21 Ä Í 4 ² Vol. 21, No. 4 2006 7 Ì Jul., 2006 «: 1000-324X(2006)04-0833-05 - Đ ² ÆÅË Ê Ç Ì È ÌÄÉ (Á  À à 310027) Å Ø Û ÜÇ ½½ - ½ ³ Ø (MgB 4O 7 Mg 2B 2O 5) Ý X ½ (XRD) Ó Ý Æ ÏÕ ÆÙ (SEM) Ñ ÏÕÆÙ (TEM) ¹ Ý Æ Ö Á 750 C º Ü MgB 4O 7 Ý 950 C º Ü Mg 2B 2O 5 Ý Ý Æ ½ Ì Å Ç Ø Æ Î Ç Ø Ý Æ ½ Å ½½ - ½ Ø Ý µ «Å TB383 º Å A 1 ¾ Þ Þ Ñ Ö ÊÑßÁ ÐÇ [1 3], ÃÁ ÇÐ sp 2 Î Â ² Ö Đ Ü 2300 C Ç¼Î Û Ç Ê Î Þ Þ Æ ¼ÀÇ Î [4 6]. Í ºÃÁ Ç «[7], Í º Ñ Þ Ù ÑÃÁ ܹ ØÀÊ ¹Ù Ñ Á ÐÇ Í ÜÙ ÑÇÉ Æ¹ Ê «Ù Æ Ç Ñ [8], Ü ÑÆ Ö ÒÆÁ ÐÇ [9]. Ü Liu Ù [9], Cheng ¾ ÔÇ Þ [10]. Renzhi Ma Ù ÔÆ ÝÈÑ Ù Æ Ô Þ [11]. Ú Ûà ÔÚÞ [12], Ö ³ Ù Þ [13]. Qasrawi ʼÀ Mg 2 B 2 O 5 Ç Æ «[14]. Ç ¾Ñ ±Đ Ü ¾ ܻϻ» Ë «ÕÚ»± Á «Ð ÇÚ Ô Æ Ë¼À ¾¾ - ¾ Æ Þ ÑÇ ¼ Ñ [15 17], Ú¼À Û ¾¾ - ¾ Ô Þ Þ Ñ [15], Ù Þ (MgB 4 O 7 Æ Mg 2 B 2 O 5 ). «Mg(NO 3 ) 2 Æ H 3 BO 3 Ç Â Þ ¾ ÇÏ ¼À ¾¾ - ¾ Ù Þ Ç 2 ºÔ (>99%)Mg(NO 3 ) 2 Æ H 3 BO 3 1:0 1:1 1:2 1:3 Ç ± Ö ³ Æ Ü (C 6 H 8 O 7 H 2 O) Þ Ý º ¾ Ò 150 C, º ± ± «2005 07 11, ± ¼ «2005 10 14» «²ØµË (50272057, 60225010) Æ «¼± (1980 ), Å» ½ «Ã E-mail: mseyang@zju.edu.cn
834 ² 21 Ä Ö ÅÁ Ç Ó º Ó Ð ÒÁ Ä Ó 750 Æ 950 C Ô Ð 4h º» ѹ ³ÁÉĐ X ¾ (XRD, D/max ra), Ð Ö Ú (SEM, JSMT20), Ò Ö Ú (TEM, CM200/Philips, 200 kv ³ ¹)» Ô Æ Ý ¼À ÆÜ ¾ Þ ÇÞ ÞÝ Â º Mg(NO 3 ) 2 Æ H 3 BO 3 1:2 ³ÆÜ 750 C Ð 4h º Å» Ô Æ Ë 3 Å ³ Ó 1 Ï 750 C 4h º Æ XRD Ó Fig. 1 XRD patterns of the products calcined at 750 C for 4h XRD, TEM Æ SEM Ô ± Ö Å ± Î Ô 1b Æ Mg(NO 3 ) 2 : H 3 BO 3 :C 6 H 8 O 7 H 2 O=1:2:5 ¾ 750 C л Ç XRD Ô Ç ¾ Õŵ MgB 4 O 7 (a=0.860nm, b=1.372nm, c=0.795nm) ¾ Ï Â Å 31-0787JCPDS Ç Ô 1a Æ Mg(NO 3 ) 2 :C 6 H 8 O 7 H 2 O=1:5 ¾ 750 C л Ç XRD Ô Ç¾ ÕÅ Ñ MgO(a=0.421nm) Ó 2 Mg(NO 3) 2:H 3BO 3 ½ 750 C 4h º Æ TEM Fig. 2 TEM images of the as synthesized samples with different ratios of Mg(NO 3) 2:H 3BO 3 (a) 1:0; (b) 1:1; (c) 1:2; (d) 1:3
4» ß ÈŽ½ - ½ Ø Ý 835 Ô 2 Æ 750 C л Ç TEM Mg(NO 3 ) 2 :H 3 BO 3 :C 6 H 8 O 7 H 2 O ¾Ç Ô Ý 1:0:5(Ô 2(a)), 1:1:5(Ô 2(b)), 1:2:5(Ô 2(c)) Æ 1:3:5(Ô 2(d)). ³ H 3 BO 3 Æ Ý 45nm Ç MgO Þ Ê Mg(NO 3 ) 2 :H 3 BO 3 :C 6 H 8 O 7 H 2 O Ý 1:1:5 Æ 1:2:5 Ç ¾ Ç Þ Ç ÛÔ Æ 100 200 Æ 200 500nm. Mg(NO 3 ) 2 :H 3 BO 3 :C 6 H 8 O 7 H 2 O Ý 1:3:5 Þ ¾ À Ó ÝÖÉ Ç Þ Ç ¾ Í «Mg(NO 3 ) 2 Æ H 3 BO 3 Ç Ï ËÜ ¾ Ë Ô 2(c) Ç ÔÆ MgB 4 O 7 Þ Çµ Ö¾ Ô Í MgB 4 O 7 Þ Æ Ç ÀÔ 2 Í È Þ Ä ¾ Î Ó 3 Mg(NO 3):H 3BO 3:C 6H 8O 7 H 2O=1:2:5 ½ 750 C 4h ÄÀÆ MgB 4O 7 Ý Æ SEM Fig. 3 SEM images of MgB 4O 7 nanorods synthesized by heat treatment of Mg(NO 3):H 3BO 3:C 6H 8O 7 H 2O=1:2:5 gel at 750 C for 4h (a) Top view; (b) Cross section view Ó 4 Mg(NO 3):H 3BO 3:C 6H 8O 7 H 2O=1:2:5 ½ 950 C ÄÀÆ Mg 2B 2O 5 Ý Æ XRD Ó (a) TEM Ó (b) Fig. 4 XRD pattern (a) and TEM image (b) of Mg 2B 2O 5 nanorods synthesized by heat treatment of Mg(NO 3):H 3BO 3:C 6H 8O 7 H 2O=1:2:5 gel at 950 C Ô 3 Æ Mg(NO 3 ) 2 :H 3 BO 3 :C 6 H 8 O 7 H 2 O=1:2:5 ¾ 750 C л MgB 4 O 7 Ç SEM (a) Æ ÊÔ (b) Æ ßÔ Ô Í Þ ÚÞ ÆÅÆ Î ¾ Ç Ú ÅÞÝ Ç ¾Ñ ¾ Ô 4 Æ Mg(NO 3 ) 2 :H 3 BO 3 :C 6 H 8 O 7 H 2 O=1:2:5 ¾ 950 C Ð 4h» Ç XRD Ô Æ TEM Ǿ Õŵ Mg 2 B 2 O 5 (a=0.615nm, b=0.922nm, c=0.312nm, α =
836 ² 21 Ä 90.47, β = 92.15, γ = 104.4 ) ¾ ÏÂÅ 15-0537JCPDS Ç Í ÚĐ Ð» Å 750 C Þ Ç ÅÁÇ Mg 2 B 2 O 5 Þ Ç ÊÝ 170nm. Ó 5 Mg(NO 3):H 3BO 3:C 6H 8O 7 H 2O=1:2:5 ½Ï º Æ TEM Ó Fig. 5 TEM images of the samples synthesized by heat treatment of Mg(NO 3) 2:H 3BO 3: C 6H 8O 7 H 2O=1:2:5 gel at different temperatures (a) 450 C; (b) 550 C; (c) 650 C Â Þ Á Ê ÍÕ Þ Ç ¾ Æ VLS [18,19]. Ý Â 450 550 650 C º Mg(NO 3 ):H 3 BO 3 :C 6 H 8 O 7 H 2 O=1:2:5 ¾Ð 4h. Â Ô 5. 450 C Ð Á Þ Ò Æ ÞÊ Æ 550 C ÞÊ Á Þ Æ 650 C Ç Þ Ô 5(c) Ç Ô Æµ Ö¾ ÀÔÍ 650 C Ç Þ Æ Ç Â «ÚºÝÍ Ù È Ù Þ Ç ¾«H 3 BO 3 250 C ÝÂÔ B 2 O 3, B 2 O 3 450 C ݼ ÔĐ Ç Ü Mg(NO 3 ) 2 330 C ÝÂÔ Ñ Ä 4H 3 BO 3 = 2B 2 O 3 (solid) + 6H 2 O(gas) (1) 2Mg(NO 3 ) 2 = 2MgO(solid) + 2NO 2 (gas) + O 2 (gas) (2) MgO + 2B 2 O 3 = MgB 4 O 7 (solid) (3) 2MgO + B 2 O 3 = Mg 2 B 2 O 5 (solid) (4) MgO Ê Ô Á¼»Ç B 2 O 3 Ì B 2 O 3 ÌÁ VLS ¾ Ç Í Ê ÞÝ Þ Ç ¾ MgO Ê Æ B 2 O 3 B 2 O 3 Ì MgO Ê Ù Þ ÀÄÜĐ ËĐ Á Þ ÜĐ ( 750 C ) µ«þ Ý 750 Æ 950 C Ç Ô Ý MgB 4 O 7 Æ Mg 2 B 2 O 5, 750 C MgB 4 O 7, 950 C Mg 2 B 2 O 5. ³ÆÜ Ç Â ÅÍÇ Þ Ç Ó Ô± Û Í ÆÜ Â Áû ÅÍ ÇÞ 4 ¾¾ - ¾ Đ Ð Ù (MgB 4 O 7 Æ Mg 2 B 2 O 5 ) Þ ß Â XRD 750 C л Ý MgB 4 O 7, 950 C л Ý Mg 2 B 2 O 5. ß TEM
4» ß ÈŽ½ - ½ Ø Ý 837 Í Þ Ç ¾ Í «Mg(NO 3 ) 2 Æ H 3 BO 3 Ç Ï Ù Þ Ç ¾«È ¹ [1] Gudiksen M S, Lauhon L J, Wang J, et al. Nature, 2002, 415: 617 620. [2] Calvert P. Nature, 1999, 399: 210 211. [3] Sha J, Niu J, Ma X, et al. Adv. Mater., 2002, 14: 1219 1221. [4] Yang Q, Sha J, Xu J, et al. Chem. Phys. Lett., 2003, 379: 87 90. [5] Yang Q, Sha J, Ma X, et al. Supercond Sci. Technol., 2004, 17: 31 33. [6] Yang Q, Sha J, Wang L, et al. Physica E, 2005, 27: 319 324. [7] Peng L M, Zhu S J, Ma Z Y. Mater. Sci. Eng. A, 1999, 265: 63 70. [8] Furetta C, Prokic M, Salamon R, et al. Appl. Radiation and Isotopes, 2000, 52: 243 250. [9] LIU Y, LI Q, FAN S. Chem. Phys. Lett., 2003, 375: 632 635. [10] Cheng C, Tang C, Ding X X, et al. Chem. Phys. Lett., 2003, 373: 626 629. [11] Ma R, Bando Y, Sato T. App. Phys. Lett., 2002, 81(18): 3467 3469. [12] Ma R, Bando Y, Sato T, et al. J. Am. Chem. Soc., 2002, 124: 10668 10669. [13] Ma R, Bando Y, Golberg D, et al. Angew. Chem. Int. Ed, 2003, 42: 1836 1838. [14] Qasrawi A F, Kayed T S, Mergen A, et al. Mater. Res. Bull., 2005, 40: 583 589. [15] Yang Q, Sha J, Ma X, et al. Letters, 2005, 59: 1967 1970. [16] ß ²ÆĐ É (LI Yu, et al). ³Ð ( ), 2005, 20(1): 71 76. [17] ØØ Ð É (ZHANG Wei-Wei, et al). ³Ð ( ), 2001, 16(1): 10 15. [18] Wanger R S, Ellis W C. Appl. Phys. Lett., 1964, 4(5): 89 90. [19] Duan X F, Wang J F, Lieber C M. Appl. Phys. Lett., 2000, 76(9): 1116 1118. Abstract: Synthesis of Magnesium Borate Nanorods by Sol-Gel Process JIANG Ji-Wei, WANG Lei, YANG Qing, YANG De-Ren (State Key Lab of Silicon, Zhejing University, Hangzhou 310027, China) The magnesium borate (MgB 4 O 7 and Mg 2 B 2 O 5 ) nanorods were fabricated with magnesium nitrate, boric acid and citric acid as the starting reagents by the sol-gel method. The structures and morphologies of the nanorods were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the products synthesized by calcining were MgB 4 O 7 at 750 C and Mg 2 B 2 O 5 at 950 C. The ratios of diameter and length of the nanorods can be controlled by adjusting the proportion of Mg(NO 3 ) 2 and H 3 BO 3. The self-catalytic mechanism was used to explain the growth of the magnesium borate nanorods. Key words sol-gel; magnesium borate; nanorods