50(4)-10.fm

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1 2006, Vol. 50, No. 4 Printed in the Republic of Korea 칼코겐이도핑된망간산화물의저온합성연구 k Á z Á, *Áy, * y w ù w yw x ù l w» ww ( ) Chimie Douce Synthesis of Chalcogen-Doped Manganese Oxides Seung Tae Lim,GDae Hoon Park, Young Soo Yoon, *, and Seong-Ju Hwang, * Center for Intelligent Nano-Bio Materials (CINBM), Division of Nano Sciences and Department of Chemistry, Ewha Womans University, Seoul , Korea Department of Advanced Technology Fusion, Konkuk University, Seoul , Korea (Received July 13, 2006). eg v y yy mw w w. X z y v yw d birnessite, š v l α-mno2 y ùkü. l v z vj. EDS l eg ƒ y ü w 4-7% v y w. yw w k X Ÿ (XAS) w w. Mn K- XAS l +3/+4ƒ yw ƒ k ƒ q y y w. Se K- Te L1- XAS Se Te ƒ y KMnO 4 mw +6ƒ y. y k w p ƒ w». : eg v; y ; yy ; d ; l ; X Ÿ ABSTRACT. Chalcogen-doped manganese oxides have been prepared by Chimie Douce redox reaction between permanganate and chalcogen element fine powder under acidic condition (ph = 1). According to powder X-ray diffraction analyses, the S- and Se-doped manganese oxides are crystallized with layered birnessite and tunnel-type α-mno 2 structures, respectively. On the contrary, Te-doped compound was found to be X-ray amorphous. According to EDS analyses, these compounds contain chalcogen dopants with the ratio of chalcogen/manganese = 4-7%. We have investigated the chemical bonding character of these materials with X-ray absorption spectroscopic (XAS) analysis. Mn K-edge XAS results clearly demonstrated that the manganese ions are stabilized in octahedral symmetry with the mixed oxidation states of +3/+4. On the other hand, according to Se K- and Te L 1-edge XAS results, selenium and tellurium elements have the high oxidation states of +6, which is surely due to the oxidation of neutral chalcogen element by the strong oxidant permanganate ion. Taking into account their crystal structures and Mn oxidation states, the obtained manganese oxides are expected to be applicable as electrode materials for lithium secondary batteries. Keywords: Chalcogen Doping, Manganese Oxides, Chimie Douce Reaction, Layered Structure, Tunnel Structure, X-ray Absorption Spectroscopy 315

2 316 ká zá Áy y, p, y ƒ wš pw w yw w w, ù ú f š. p yw yw 1 ey w w yw w ey ƒ w š. y y p, yy, Ÿ w ƒ š š. 2-5, y,, t w w f ƒ š. w, y š mw š Mn +7 ù Mn w yy w +2 w ƒ š. 2 w y mw y 1 ù w w œw p ey mw w. 6, ¾ š y w ey 3d w. w, y ey w w ƒ w ù ¾ s ƒ w š. 7 yy w e g (S, Se, Te)ƒ v y w w. w, yw wp y ƒƒ X z (XRD) X Ÿ (XAS) w w. x w w. ey eg energy dispersive spectroscopy(eds) w y w. yw w XAS x sw ƒ» (PAL) 7C extended X-ray absorption fine structure(exafs) e w w. XAS l» y» w n d. rp t Mn, Se, Te rp wì d w t yw. y S K- S L 1- ƒ swƒ» 7C x ù d w w. X-ray absorption near-edge structure (XANES) rp k(background) l z EXAFS w xw vq mw ³ y(normalization) w. 8 š eg v y w XRD q l Fig. 1. y v 2θ= (003) (006) vjƒ yw d ƒ d xk y d birnessite eg S, Se, Te ƒ v y M KMnO eg yww z ph=1 w 60 C 24 w w w. w z y û w» w z z 80 C w. Cu K α X w f vl eƒ e XRD» m Fig. 1. Powder XRD patterns for the chalcogen-doped manganese oxides with (a) sulfur, (b) selenium, and (c) tellurium.

3 y. w v x z ql 2 2 œ l α-mno2 w w. l y v a = Å, c = Å ƒ v a = Å, c = Å ƒ y w. yw l v z vjƒ yw X ùkü. eg w ³ w ƒ ƒ v w q. ù, w y x eg j»ƒ f d y j» v α-mno 2 x eg v y w 317 ù l v w j» e w w w. Fig. 2 EDS l y ü w 4-7% eg v y w. EDS ±2%. e g w Ÿ Se K- Te L I- XANES rp œ d y. sk w y w. eg v y k y w» w y w Mn K- XANES rp t Fig. 2. EDS data of the chalcogen-doped manganese oxides with (a) sulfur, (b) selenium, and (c) tellurium. Fig. 3. (a) Mn K-edge XANES spectra for the chalcogendoped manganese oxides with sulfur (solid lines), selenium (dashed lines), and tellurium (dot-dashed lines), in comparison with those for the references Mn 2O 3 (squares) and MnO 2 (triangles). (b) Expanded views of the above spectra for preedge region of ev. 2006, Vol. 50, No. 4

4 318 ká zá Áy Mn 2O 3 MnO 2 w Fig. 3 w. Fig. 3b ù (pre-edge region) 1s k 3d k w w vj P P vj» œm. ƒ 9 ³e(dipolar selection rule) w x» d p k yw ú ƒ vj»ƒ. Fig. 3 q y. w l +3ƒ y k wù vjp s³ y kƒ +3ƒ vj P P +4ƒ w ƒw P vj»ƒ f. 10 Fig. 3b eg v y vj P P vj P +4ƒ t MnO2 w vj». y ü +3/+4 yw ƒ k ƒ ùkü. w eg v y (main absorption edge) eƒ t Mn2O3 MnO2 ew w e. eg v y y v yw û yw y k yw û w. (mainedge region) t 1s k 4p k x w w ƒ vj. vjb w l vj MnO6 q ƒ œ jš ú e ùký š. 10 Fig. 3 y v yw úe vjbƒ w yw vj»ƒ w. XRD y y v yw œ MnO6 q d v yw MnO6 q œ Õ œ wì w α-mno 2 y w. š, l v XRD Fig. 4. Se K-edge XANES spectra for the selenium-doped manganese oxide (solid lines) and the references Se (dashed lines), Na 2SeO 3 (dot-dashed lines), and Na 2SeO 4 (squares). l ³ w w rp l α-mno 2 y ƒ w. eg v y l y k Se K- Te L1- XANES mw w. Fig. 4 v y t Se 0, Na 2Se IV O 3, Na2Se VI O4 yw Se K- XANES rp ùküš. Se K- 1s k 4p k w w vj Aƒ. vj» k w e y k w. Fig. 4 Se 0 (4p 5 ), Na 2Se IV O 3 (4p 1 ), Na 2Se VI O 4 (4p ) j 0» vj Aƒ. w» vj w k 4p k w. v y +6ƒ t Na2SeO4 w vj». l y ü v +6ƒ xk w. l v y t Te 0 Na2Te O3 IV Te L1- XANES rp Fig. 5

5 Fig. 5. Te L 1-edge XANES spectra for the tellurium-doped manganese oxide (solid lines) and the references Te (dashed lines) and Na 2TeO 3 (dot-dashed lines).. r Se K- w, Te L1-2s k 5p k w w w vj Aƒ. vj» k w e l y k w. Fig. 5 w l v y +4ƒ l t Na 2Te IV O 3 (5p ) w j» vj Aƒ 1. w ww +6ƒ l t w rp d ù y ü l ƒ +6 ƒ (5p 0 ) k w. w Se K- Te L1- XANES ww y w eg ƒ w y KMnO4 mw y k ww. y k d ü t w w l j EDS w. y w l yw ƒ k(+3/+4) ƒ q y 2006, Vol. 50, No. 4 eg v y w 319. w, eg d l xk š y w. w œm p d k ƒ w w d yw p ƒ w» x w w. yy w y,, l v y w w w p sƒ ww. XRD e g d l y w. EDS Se K- Te L 1- XANES l y +6ƒ eg y ü œ y y w. Mn K- XANES yw ƒ k ƒ q y y w. w p ƒ w w p ( w» ) w. swƒ» x w» swœ w w w. x 1. Tejuca, L. G.; Fierro, J. L. G. Properties and applications of perovskite-type oxides, Marcel Dekker Inc., New York, Thackeray, M. M. Prog. Solid State Chem. 1997, 25, Toupin, M.; Brousse, T.; Belanger, D. Chem. Mater. 2002, 14, Xi, Y.; Reed, C.; Lee, Y. -K.; Oyama, S. T. J. Phys. Chem. B, 2005, 109, Sakai, N.; Ebina, Y.; Takada, K.; Sasaki, T. J. Phys. Chem. B, 2005, 109, Hwang, S.-J.; Park, H. S.; Choy, J.-H.; Campet, G. Chem. Mater. 2000, 12, Park, D. H.; Lim, S. T.; Hwang, S. -J.; Yoon, C. S.;

6 320 ká zá Áy Sun, Y. K.; Choy, J.-H. Adv. Mater. 2005, 17, Teo, B. K. EXAFS: Basic Principles and Data Analysis, Springer-Verlag, Berlin, Treuil, N.; Labrugère, C.; Menetrier, M.; Portier, J.; Campet, G.; Deshayes, A.; Frison, J. C.; Hwang, S. J.; Song, S. W.; Choy, J. H. J. Phys. Chem. B 1999, 103, Hwang, S.-J.; Kwon, C. W.; Portier, J.; Campet, G.; Park, H. S.; Choy, J.-H.; Huong, P. V.; Yoshimura, M.; Kakihana, M. J. Phys. Chem. B 2002, 106, 4053.