Korean Chemical Engineering Research

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(1)Korean Chem. Eng. Res., Vol. 43, No. 1, February, 2005, pp. 71-75. La0.5Ca0.5MnO3 ÏG Pellet£ ·»Ïh Z Û{L |. <+ ¿ o O< †. UñÉ¬HG @Hê ÖQ {g 3Í 249-1 ¸ ö ³ [¤, 2004¸ 10ö 15³ >). 136-742 (2004 2 4. Structural Elucidation and Magnetical Properties of La0.5Ca0.5MnO3 Powders and Pellets Miewon Jung†, Jiyun Lee and Hyunjung Kim Department of Chemistry, Sungshin Women’s University, 249-1, Dongseon-dong 3-ga, Seongbuk-gu, Seoul 136-742, Korea (Received 4 February 2004; accepted 15 October 2004). ß È. ðM¬ É, I] í0¯ La Ca MnO ~Sê pellets Î-r rk³ fÆG. ùs- 5õ ¡@Q- »o Q0Ñ ¬g FT-IRê CP/MAS C solid state NMR spectroscopy -Ê XRD Ùs «Äg gÆ¡@õ îûG. «5 Æ 9Ss <4Ý, .g ICP-AESõ «ÄGk, ½É¿,Q è³õ FE-SEM/EDS³, Â§gÆQ É Ò¡o TEMk³ îûG. VSMs «ÄGñ É,J U s oÝIk -5(T )2 236 KÑ +_æÉ. 0.5 13. 0.5. 3. c. Abstract − La0.5Ca0.5MnO3 colossal magnetoresistance (CMR) powders and pellets were synthesized by sol-gel process. The structural changes were investigated by FT-IR, CP/MAS 13C solid state NMR spectroscopy and XRD. The particle characterization, microstructure of sintered samples, and cation composition of gel powders were studied by FESEM/EDS, TEM and ICP-AES. The structure refinement reveals that La0.5Ca0.5MnO3 has orthorhombic, perovskite type unit cell. The magnetic characterizations were identified through measurement of magnetic moment by VSM. Key words: La0.5Ca0.5MnO3, CP/MAS 13C NMR, TEM, ICP-AES, VSM. 1.. C «. ¨, I5Y Ú è³K áL fÆQ ço êHJ, D¬J Ä « ÍDG³ Q« «ÄæÊ À. Hervieu Ù[3]o Prê Sr a Ñ dís ñ6 ÆQÑ Y Gñ ·êMÉÂ s «Äg O ³A«T dí gÆõ é. Î-r ro èí0 ÜÍ, Äk 0 Ú , Í¤~g ä ÆQ, P , ñk, HY¨, pH Ù ñ6 Í( í- dHJ Æ Q« ¡¤³ ÊÄGj ê. Í¤~g õ (õÿD .g Ä kÑ ÿ2 örê pHõ ¡dÿM÷ S«T í0s Í G2 ör« À. «Ë örs 0g r @ Í .s(

(2) ½ ÉÍ è³GÊ Â§K ¿Dõ äj æ³ «Ñ ¬K õgÍ lè Gj ,}æÊ À[4]. ShimizuQ Li Ù[5, 6]o Ê~Éõ «ÄGñ «5ê HYê rs OÇ ù~g E Â§K ~Ss Y K à Àk, «) Ê~É Mg Äo _d 5Q õ ?2) O®K òOs KÊ ÝÊG. Ê~É2 «5 Ñ ¬K > « uG÷ «5Ës kÎ è³Gj HY ¤ À2 ßY« À. Ê~É Íf¯ poly(ethylene glycol)o ÄU Ñ «5Ëê D ÊÄGñ «5Ës Ñ ~E Æ « è³K HYís OË ¤ Àk, ÄkÍ fMî ) Ê~É. I« «5s .6 Ë _dõ µfg Â§K ~S. z ÉDß KåÑ ¶ M¬K { MRs ÷2 ðM ¬ ÉDI](colossal magnetoresistance, CMR) Áê U8o É ()³2 äÉ ) QõÑ ãÉ k³ IK I] ¡ dÍ M«5 zÑ ÊéG2 a«[1]. ó§¬ (¥ Éõ g G2) 1®K h é0³ Ùé « £~G÷ JÄ éfY Ùs íGD .g «ËÑ ¬K í Ú Dá èn Ñ ¬K õgÍ 1®G. O³A«T aÑ dí ÉgÆ2 fÆ örê «5Ë ¬J ¿D -Ê 4n¶ «5Ë dH ·W Ùê ço ñ6 Í( ÆQÑ s ç2. O³A«T aÑdí fÆ örÑ2 citric acidõ «5 S«ªf³ ÄG2 citrate à_r, dí Eo ! ~Ss Ê5Ñ äÿ 2 Ê är, < «Ã gí0s < 9Ñ ÍGñ Í ¤ ~gE ~Ss Y G2 Î-r à_ Ù« À[2]. Î-r ro äs ÄUÑ èÿD )éÑ ~ª fÆÍ Ä«GÊ Ê † To. whom correspondence should be addressed. E-mail: [email protected]. 71.

(3) _Âòö«(Oö6_. 72. s Y Gj G, I5Ñ O³A«T s »j K[7]. Ê rê - Î-r rs «ÄG

(4) ~É¤CÑ HYæ´ dH ·Jk³ J¢K WS ÆY« ÍDG. < «Ã÷ KD Ë HYí« 4r -ÑÃõ jhE èí0 8_ s «

(5) 5Ñ 8_K ÄU =Í K(æ³ í« Ä«g( ñ6 ÜÍ áL fÆÑ Ä« ÍDg,. K, «5Ë Æ Y ÍD « g( gÆõ è³Gj ä2 HYê O³A «T ÞY dís WGJ o 5Ñ ÷ô ¿D ¤Ck³ » s ¤ À. 0 fÆörê ùs- ÆQ Ùo CMR aÑdí gÆQ ÉDJ 0Ñ s ?2 O®K ¡¤«³ fÆör Ñ ñ gÆQ U Ñ ¬K õgÍ 1®G. á õgÑ2 4§4§« jhê è í0s >Gñ Ê ~É Íf³ PEGõ ÆYE La Ca MnO ~Sê Wgs Y G. FT-IR(fourier transform infrared spectroscopy), CP/MAS C solid state NMR(nuclear magnetic resonance spectroscopy), XRD(Xray diffractometer) Ùk³ äê_s JG

(6) OÑõ <4á ùs- 5õ ¡dÿ

(7) _gÆõ îûG. 0 «5 Æ WSo ICP-AES(inductively coupled plasma atomic emission spectrophotometer)³ e¯GÊ, SEM(scanning electron microscope)ê EDS(energy dispersive(X-ray) spectrometry) Ú TEM (transmission electron microscope)k³ _ Â§gÆ, ¿DQ ¡ Q Ò¡ Ùs îûG. K, ùs-õ }K pelletÑ ¬Gñ VSM(vibrating sample magnetometer)ßWõ «ÄGñ É U s õgG. 0.5. 0.5. 3. 13. 2.. / . ~Ss Y GD .Gñ lanthanum(III) 2,4-penê calcium(II) 2,4-pentanedionate 5 mmols propionic Q HYÄk(4:1) 250 mlÑ õ«Ê, manganese(III) 2,4-pentanedionate 10 mmols ´ 5Ñ GäZ. 24Ñ 8 5Ñ ä 15 wt% poly(ethylene glycol) ÄU 1.44 mlõ ÍZ. 4Ñ 8 80 CÑ hÍ á, 48Ñ 8 5Ñ £~¾ Gä E To ôº+ ÄUs »É. «Ñ ¬K ä ,} _2 FT-IR spectroscopy³ e¯G. 8_K Î ÄUÑ Äkõ è r³ OÇ {, 150 C ,à1 Ñ 48Ñ 8 QÆE r ~Ss »É. Agate mortar³ Â §Gj ~GK 0õ W5 5 C/min³ Gñ 250, 300, 400, 500, 700, 900 C -Ê 1,100 CÑ 1Ñ 8 ùs-G. Pellet fÆro 800 CÑ ~Ss 1Ñ 8 Gà_s ¤}G. Agate mortarÑ Üj ~GGÊ KF pressõ «ÄGñ ò0 <uHk³ K á, 1,100 CÑ 1Ñ 8 Zk « Ë fro Fig. 1Ñ Ñ÷Gj ÷É[8]. ùs- 5Ñ ñ dYí gÆ¡d -Ê ä OÑ @ í Ùs <4ÝD .g J ~ ~D(fourier transform infrared spectroscopy, Nicolet Impact 410)³ 4,000-400 cm p.Ñ KBr ê 0õ ÎÎ 100¬ 1³ HYGñ A¿ k³ OË´ +_G . K, ~S =Ñ 300 MHz CP/MAS C solid state ÉDà ~ D(nuclear magnetic resonance spectroscopy, JNM-ECP300, JEOL)õ «Äg gÆõ ~G. _ s e¯GD .Gñ X- ¡Q ~D(X-ray diffractometer, Philips X’PERT-MPD)³ CuKα, La0.5Ca0.5MnO3. tanedionate 5 mmol acid methanol. o. Fig. 1. Flow chart of experimental procedures. *acac=2.4-Pentadionate, PEG=Poly(ethylene glycol).. ? p. 2θ=20-80 , scan stepo 0.04 -Ê scan o ÆQÑ ¤}G. fÆê 0 «5 Æ WSo KY ñ¶ K ö~ D(inductively coupled plasma atomic emission spectrophotometer, 138 Ultrace)õ ÄG ñ +_G. ½É¿D, ~¯ -Ê ½É= Ùs <4ÝD . g ? MÉÂ (field-emission scanning electron microscopy, JSM-6700F, JEOL, JAPAN)ê EDS(energy dispersive X-ray spectrometer, EDAX)õ ÄGñ ÍMF 15 kVÑ 15,000 S³ +_GÊ, DªJ ÆÊê «5 millings Mn ·êMÉÂ (Transmission electron microscopy, CM12, Philips)s «Äg 120 kV ÍMFÑ ¤}G. É U s oÝD .g U0³ 77 K b( -Î á VSM(vibrating sample magnetometer, VSM 7300, Lake Shore)s «ÄGÊ, K 5õ 9-

(8) T « 5 òb( +_G. o. 40 kV, 30 mA, time 0.08 sec. c. o. o. o. o. o. o. −1. 13. ¤@¤ C43× C1 2005 2. o. 3.. ûG Z +{. 2 150 CÑ QÆ r ~Sê 300 CQ 500 CÑ ùs-K ~SÑ ¬K FT-IR spectra«. r ~S«÷ 300 CÑ ùs-K ~SÑ îûæ2 3,400 cm z o 2 -OH ,Ñ D¯G

(9) -OHDÍ ÊéWs ÂK. r ~SÑ O î+æ2 1,552 cm ê 1,467 cm )¿Ëo COO 2 -C=CHOH W¬ê ¬ ,Ñ D¯K. 1,380-1,420 cm Ñ Ý«2 2í uK )¿Ëo CH yÎ , ê³ »´(2 ¤ )¿ Ë«. 1,020 cm ê 1,076 cm 2 O-C-O , 2 CH y Î ,(rocking vibration)Ñ K a«, C-C ,o 930 cm Ñ ÷û. 300 CÑ ùs-K ~S Î, 3,000 cm s -CH , )¿2 ÊéG( :k÷, 1,700 cm s -C=O , )¿Ëo ñM¾ ÷û. ùs- 5 ÍQ Wÿ -OH DQ KDD ËÑ D¯G2 )¿Ëo ÝGD ÊG 500 CÑ 2 Ý«( :2. 300 CQ 500 CÑ ùs-K ~SÑ2 O Fig. 2(a). o. o. o o. −1. −1. −1. −. −1. 3. −1. −1. 3 −1. −1. o. −1. o. o. o.

(10) La0.5Ca0.5MnO3. ~5ê pellet É,J 0. 73. Fig. 3. X-ray diffraction patterns of La0.5Ca0.5MnO3 powder and sintered pellet after different heat treatments.. Fig. 2. (a) FT-IR and (b) CP/MAS 13C solid state NMR spectra of La0.5Ca0.5MnO3 gel powders obtained from different heat treatments.. Ñ Êéõ < ¤ À2 oxycarbonate )¿Í 800 cm Ñ îû ê. K, 842 cm ¤ 2 ôí OÑ ãGj .æ´ À2 CO Q O-C(O-R) yÎ ,Ñ K a«[9]. 250 CQ 400 C Ñ ùs-K ~Ss CP/MAS C solid state NMR spectroscopy ³ îûK Fig. 2(b)2 É s Ê À2 í0«´ MJk³ o õ ÝñC. 250 CÑ ùs-K ~SÑ À´ 200 ppm s )¿2 -COO O C=O D Êéõ -Ê 160 ppmê 130 ppm )¿Ëo -C=C-D )é«, «Ëo OÑ ¯ oxycarbonate ) éÑ D¯G2) «2 FT-IRê XRD É0Ñ îûê. 400 C Ñ ùs-K ~S Î _dÍ ,}æ

(11) )¿Ë §DÍ »g((O -C=C-Q -COO Ú -CH DËo ñM¾ ÊéK. CuKα ³ ²ßÑ ~Sê pelletÑ ¬K _gÆõ X- ¡ QDõ ÄGñ ~GÊ «õ Fig. 3Ñ ÷É. O³A «T « 700 CÑ æD ÊG{s < ¤ ÀÊ, 1,100 C Ñ2 _ « UM¾ æ´ a =5.4739 Å, b =5.4128 Å, c =7.7768 Å É ¤õ ä2 ö_ª gÆ»s e¯O ¤ À. «2 Chenê Cheong[10]ê Radaelli Ù[11] õg êQ ³j K. La Ca MnO ÑQ K÷Í(³ 700 CÑ O³A« T « OÑ ¯ oxycarbonateQ Wÿ îûæ÷, ùs- 5Í ÍWÑ ¶ OÑ Ñ K ¡Q )¿Í ¶(Ê O³A«T Ñ K )¿Í »Gj ßK[8]. Æ Wõ <4ÝD .Gñ KY ñ¶ K ö~ Dõ «Ä −1. −1. 2− 3. o. o. 2. 13. o. −. o. −. o. o. o. o. o. o. 0.8. 0.2. 3. Fig. 4. FE-SEM micrograghs of La0.5Ca0.5MnO3 (a) powder and (b) sintered pellet at 1,100 oC/1 h (c) corresponding typical EDS spectrum confirming the composition.. g 3d pellets ~Gk, ÎÎ èàk³ «5 Æ W õ <4É. ~ê Æ W2 La 37.44%, Ca 15.08% -Ê Mn 47.48%³ La Ca MnO »s < ¤ ÀÉÊ è,ê éË É0Q ³jG[1, 12]. ~Sê ê pellet Â§gÆõ < 4ÝD .g 15,000 SÑ FE-SEM/EDSõ +_Gñ Fig. 4Ñ ÷É. »K _ ßs îûO ¤ Àk ~S è½É ¿D2 380 nm«ÉÊ, ê pellet Î2 400 nm«É. ~S ê pellet ½É¿D2 Ã ó«Í ÇÉk pellet ÎÍ ~SÝ ½ÉÑ õQ è³Í

(12) Î¤G. Fig. 5(a)2 5Ñ TEMk³ îûK La Ca MnO Ñ ¬K bright field s ÷ ak³ ÷ô ¿D è³K =õ (n, Fig. 5(b)Ñ2. ö_ª gÆõ e¯O ¤ À2 O³A«T .§¯Í îûê. U 0 GÑ 77 Kb( ÉDßs ¯ÍG( :o =³ 0.576. 0.424. 0.5. 0.5. 3. 3. Korean Chem. Eng. Res., Vol. 43, No. 1, February, 2005.

(13) _Âòö«(Oö6_. 74. .5 gÑÑ Édà« Íß Gj ÝG2 (Y¯, ãÉD ³ M«Í ³´÷2 5 T =236 Kõ T (curie temperature)³ _G. +_K Éd àk³z - 5õ _G2 öro É d à« ÊG2 5³ _G2 örê 5Ñ ¬K Éd à ¡dÍ Íß K Þk³ _G2 ör Ù« À. K, u 86 K « G³ 5Í sÝÑ ¶ Éd à« ÝG2 ak³ Ý4 « (Y Ñ äãÉ ê charge ordering(CO) « ³´ÿ ak³ D¬ê [12]. Chenê Cheong[10] Ê äk³ »´, La Ca MnO ~SÑ ¬K MÉ ¡Q ×Ñ Jk³ ãÉ charge-disordering ê äãÉ charge/orbital orderings Ñ îûGk 5Í 4? sâs ) ª2 è³Gj äãÉ charge ordering « ³´ûÊ ÝÊG[13]. O³A«T aÑ díÑ Æ W÷ «5 gá -Ê Wê ço ®¯Ëê ¨ K ³62 Ñ g M«Í ³´÷j æ´ z¤Jk³ ñ _ gÆ ÊéGj æÊ - 5Ñ s ?j ê. c. c. 0.5. Fig. 5. (a) TEM bright-field image of La0.5Ca0.5MnO3 powder at room temperature. (b) Pattern is indexed on the basis of the orthorhombic, perovskite-type unit cell.. 0.5. 3. û «. 4.. õ Äg Î-r rk³ Y K O³A«T La Ca MnO ~Sê pelleto è³GÊ ÆÊK gÆõ (É. ùs- 5õ ¡ dÿ

(14) »o )«õ «Äg ~K ê oxycarbonate OÑ s M° _« ös < ¤ ÀÉ. 700 C « Ñ ÍÍ carbonateÍ UM¾ fMæ´ a =5.4739 Å, b =5.4128 Å, c =7.7768 Å É ¤õ ä2 ö_ª gÆ³, dHJ Æ W2 La Ca MnO «É. FE-SEM/EDSQ TEMk³z ÷ô ¿D è³Gj ~¯ ê _s e¯O ¤ ÀÉk, _ ¿D2 ~S Î 380 nm, pellet Î 400 nm«É. ¯d Éd(M )ào 77 KÑ 35.97 emu/g«Ék, T ào 236 KÑ »´. PEG. 0.5. 0.5. 3. 0.424. 3. o. o. o. o. 0.576. s. c. [ ÷ « õg2 2003¸ «§ä á H¬,õgW (òÑ Gñ õgæÉk «Ñ Ý Ã?n.. +S. Fig. 6. (a) Hysteresis loops of the La0.5Ca0.5MnO3 pellet at 77 K, (b) Temperature dependence of magnetization for La0.5Ca0.5MnO3 pellet.. Î á, 5õ 9-

(15) ÉDßs ¯ÍGñ T « 5 òb( ÉD HìTõ +_G. Fig. 6(a)Ñ «tËk³z »´, ¯d Éd(M )ào 77 KÑ 35.97 emu/g³ +_æÉ. Fig. 6(b)2 5 ¡dÑ ñ ÉdË« UOWs Ýñ?2) c. s. ¤@¤ C43× C1 2005 2. 1. Tokura, Y. and Tomioka, Y., “Colossal Magnetoresistive Manganites,” J. Magn. Magn. Mater., 200(1), 1-23(1999). 2. Kwon, S. W., Park, S. B., Seo, G. and Hwang, S. T., “Preparation of Lithium Aluminate via Polymeric Precursor Routes,” J. Nuclear Materials., 257(2), 172-179(1998). 3. Hervieu, M., Van Tendeloo, G., Caignaert, V., Maignan, A. and Raveau, B., “Monoclinic Microdomains and Clustering in the Colossal Magnettoresistance Manganites Pr0.7Ca0.25Sr0.05MnO3 and Pr0.75Sr0.25MnO3”, Phys. Rev. B: Condens. Matter., 53(21), 14274-14284(1996). 4. Kajinara, K. C. and Yao, T., “Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly (Ethylene Glycol). III. Effect of Chemical Additives,” J. Sol-Gel Sci. and Tech., 16, 257-266(1999). 5. Shimizu, Y. and Murata, T., “Sol-Gel Synthesis of Perovskite Type Lanthanum Manganite Thin Films and Fine Powders using Metal Acetylacetonate and Poly(vinyl alcohol),” J. Am. Ceram..

(16) La0.5Ca0.5MnO3. ~5ê pellet É,J 0. Soc., 80(10), 2702-2704(1997). 6. Li, X., Zhang, H., Chi, F., Li, S., Xu, B. and Zhao, M., “Synthesis of Nanocrystalline Composite Oxides La1-xSrxFe1-yCoyO3 with the Perovskite Structure using Poly (ethylene glycol) Gel Method,” Mater. Sci and Eng. B., 18(3), 209-213(1993). 7. Park, H. B., Kweon, H. J., Kim, S. J. and Kim, K., “Preparation of LaMO3 (M: Cr, Mn, Co) Fine Powders using PEG,” J. Kor. Chem. Soc., 38(11), 852-855(1994). 8. Jung, M. W., Lee, J. Y. and Kim, H. J., “Preparation and Characterization of La0.8Ca0.2MnO3”, J. Kor. Ceram. Soc., 40(5), 434440(2003). 9. Bilger, S., Syskakis, E., Naoumidis, A. and Nickel, H., “Sol-Gel Synthesis of Strontium-Doped Lanthanum Managanite,” J. Am.. 75. Ceram. Soc., 75(4), 964-970(1992). 10. Chen, C. H. and Cheong, S-W., “Commensurate to Incommensurate Charge Ordering and its Real-Space Images in La0.5Ca0.5MnO3”, Phys. Rev. Lett., 76(21), 4042-4045(1996). 11. Radaelli, P. G., Cox, D. E., Marezio, M. and Cheong, S.-W., “Charge, Orbital, and Magnetic Ordering in La0.5Ca0.5MnO3”, Phys. Rev. B., 55(5), 3015-3023(1997). 12. Rao, C. N. R., Cheetham, A. K. and Mahesh, R., “Giant Magnetoresistance and Related Properties of Rare-Earth Manganates and Other Oxide Systems,” Chem. Mater., 8(10), 2421-2432(1996). 13. Mori, S., Chen, C. H. and Cheong, S-W., “Paired and Unpaired Charge Stripes in the Ferromagnetic Phase of La0.5Ca0.5MnO3”, Phys. Rev. Lett., 81(18), 3972-3975(1998).. Korean Chem. Eng. Res., Vol. 43, No. 1, February, 2005.

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