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1 Jurnal f the Krean Ceramic Sciety Vl. 46, N. 6, pp. 695~699, 009. DOI: /KCERS Tranfer f Oxygen Vacancy and Prtn in Y-dped BaZrO Dae-Hee Kim, Yng-Chan Jeng, Jng-Sung Park*, Byung-Kk Kim*, and Yeng-Chel Kim Department f Material Engineering, Krea Univerity f Technlgy and Educatin, Chenan 0-70, Krea *Center fr Energy Material Reearch, Krea Intitute f Science and Technlgy, Seul , Krea (Received September 1, 009; Accepted Octber 6, 009) Y-dped BaZrO œœ v m ½ Á Á *Á½ *Á½ w» w œw *w w» ( ; ) ABSTRACT We tudied the tranfer f xygen vacancy and prtn in Y-dped BaZrO (BYZ) uing denity functinal thery (DFT). An xygen vacancy wa generated in the BYZ upertructure by replacing tw Zr atm with tw Y atm t atify the charge neutrality cnditin. The O vacancy tranfer between the firt and ecnd nearet O atm ite frm a Y atm hwed the lwet activatin energy barrier f 0.4 ev, cmpared t the ther tranfer between firt and firt, and ecnd and ecnd in the upertructure. Tw prtn were inerted in the tructure by adding a prtn and hydrxyl that were upplied by the diciatin f a water mlecule. The tw prtn bnded t the firt and ecnd nearet O atm were energetically the mt favrable. The activatin energy barrier fr a prtn tranfer in the tructure wa 0.51 ev, when either prtn tranferred t it neighbr O atm. Thi value wa well matched with the experimentally determined ne. Key wrd : Prtn cnductr, Pervkite xide, BaZrO, BYZ, Cmputer imulatin 1. r e p y (pervkite xide) š (high-temperature upercnductivity), (ferrelectricity), (piezelectricity), x» w (clal magnetreitance), š p. 1-6) r e p y ABO yw tx, (cubic) (rhmbhedral), (rthrhmbic), (tetragnal), (mnclinic) w w. 7) w, š v m (high-temperature prtn cnductr, HTPC), m (wirele cmmunicatin applicatin), š w»q. -10) v m w» ey š, (xygen inic cnductr) ƒ û. 11) š v m y y (activatin Crrepnding authr : Yeng-Chel Kim yckim@kut.ac.kr Tel : Fax : energy barrier) 0.10~1.00 ev. 1) 1 w r e p y wù BaZrO v m w ƒ š š. Gmez BaZrO ww r e p y v m (mbility) q (ctahedral)» w š, lƒ v (acceptr-dped) BaZrO v m w w š šw. 1) Björketun v BaZrO v m y p w ) Merinv Y ƒ v BaZrO v m y y w. 1) w, Gmez qp (dpant)ƒ v w BaZrO v m w» qp w š w. w Gmez Björketun mw v m y y ev š šw, x (0.44 ev). 4) Merinv v m w y y 0.41 ev x ew, v m w w. w, v w O 695

2 김대희 정용찬 박종성 김병국 김영철 696 The perpective view f BaZrO unitcell. Fig. 1. 공공의 이동에 관한 계산 연구는 보고되지 않았다. 본 연구는 denity functinal thery (DFT)로 BaZrO 에 Y O 를 첨가하여 O 공공을 생성시킨 후, 에너지 관점에 서 안정한 O 공공의 위치와 O 공공이 이동할 때 요구되 는 활성화 에너지 장벽을 계산하였다. 또한 Y-dped BaZrO (BYZ)에 물 분자를 첨가하여 프로톤의 위치와 이 동할 때 요구되는 활성화 에너지 장벽을 계산하였다.. 계산 방법 본 연구는 Vienna imulatin package (VASP) 코 드로 구현된 firt-principle generalized gradient apprximatin (GGA)을 이용하여 수행되었다. 사용된 포텐셜 (ptential) 은 prjectr-augmented wave (PAW)이며, 전자의 바닥 상 태를 계산하기 위하여 reidual minimizatin methd direct inverin in the iterative ubpace (RMM-DIIS)가 사용되 었다. Cutff energy는 500 ev이고, k-pint meh는 Mnk-hrt pack이며, 크기를 사용하였다. Smearing 방법은 반도체와 부도체 재료에 적합한 Gauian 법이며, 0.05 ev의 mearing factr가 사용되었다. Ba 6, Zr 4 와 5, O, Y 4 과 5, 그리고 H 1 상태가 사용 되었다. 사용된 cutff energy와 k-pint meh 값은 계산 시간과 계산 값의 정확도를 적절히 조절한 최적화된 값이다. 순수한 BaZrO 단위 격자를 계산하여 격자 상수를 최 적화하였다(Fig. 1). 최적화된 격자 상수 (4.5 Å)를 이용 하여 BaZrO 단위 격자를 확장시켜 초격자구조 를 생성시켰고, 생성된 Ba Zr O 초격자구조에 Y O 를 첨가하여 O 공공이 존재하는 Ba Zr Y O 초격자구조를 계산하였다. 이 때 O 공공이 에너지 관점에서 가장 안정 한 위치를 계산하였고, 또한 climbing nudged elatic band (C-NEB) 도구를 이용하여 O 공공이 이동할 때의 활성화 에너지 장벽을 계산하였다. Ba Zr Y O 초격자구조에 ab-initi 19-) 4,5) 4 1 p d d ) 한국세라믹학회지 6. The (a) perpective view and (b) chematic image include an O vacancy in Y-dped BaZrO upertructure. The O vacancy i lcated at the ecnd nearet O atm ite frm the Y atm. (c) The energy variatin a a functin f the lcatin f the O vacancy. Fig. 물 분자를 첨가하여 두 개의 프로톤을 생성시키고, 에너 지 관점에서 안정한 프로톤의 위치를 계산하였다. 또한 NEB 도구를 이용하여 프로톤이 Y과 Zr 원자 주변을 이

3 Y-dped BaZrO œœ v m 697 Table 1. The M-O bnd length and M-O-M angle in Y-dped BaZrO (BYZ) with an O vacancy. M repreent Zr r Y. V O1 Bnd length [Å] Angle [ ] Y1-O4.19 Y1-O4-Zr Zr-O.09 Zr-O-Zr Zr-O.19 Zr-O-Zr Zr4-O4.10 V O Y1-O4. Y1-O1-Zr 10.0 Zr4-O4.04 Y1-O4-Zr Zr-O-Zr 174. w y y w.. w Ba Zr O 4 Y Zr eywš w (charge neutrality) j» w O œœ k yw. Ba Zr O 4 +Y O Ba Zr 6 Y O +V O Fig. (a) Y ƒ Zr ey š O œœ Y l ƒ¾ O (ecnd nearet O atm ite) Ba Zr 6 Y O. Y ƒ Zr ey Y w (pitive charge), Y ƒ ew w. O œœ Y l O ƒ¾ O (firt nearet O atm ite) ƒ¾ O j. Fig. (b) Ba Zr 6 Y O Y ƒ w w. O1 O4 Y l ƒ¾ O, š O O Y l ƒ¾ O w. O œœ O1, Zr- O (.09 Å)ƒ Zr-O (.19 Å) w š, Zr-O-Zr Y1-O4-Zr4 ƒ ƒ ƒƒ O O4 ƒ V O1 (O1 O œœ) w w w (Table 1). w, Zr- O-Zr4 ƒ ƒ 10.0, ƒ¾ O O œœ w ƒ¾ O w e q. O œœ O, Y1-O4 w ƒ.19 Å. Å ƒwš, Zr4-O4 w ƒ.10 Å.04 Å w O4 V O w. Y1-O4-Zr4 ƒ ƒ 154. Fig.. The (a) planar view and (b) chematic image f the Y- dped BaZrO that include the H and OH. Tw prtn (white phere) are lcated at the firt and ecnd nearet O atm ite in the ame plane. (c) The energy variatin a a functin f the lcatin f the prtn in Y- dped BaZrO that include the H and OH. w» Zr-O-Zr ƒ ƒ w. Fig. (c) O œœ w y y. V O1 V O ƒ ƒƒ O4 O w» w y y ƒƒ 46«6y(009)

4 69 ½ Á Á Á½ Á½ Table. The M-O bnd length and M-O-M angle in Y-dped BaZrO (BYZ) with a water mlecule. M repreent Zr, Y, r H. Bnd length [Å] Angle [ ] H1-O Y1-O4-Zr H-O 1.00 Y1-O1-H1 0.0 Y1-O1.0 Zr4-O-H 77. Y1-O , 1.04 ev j. w V O ƒ O4 w y y 0.4 ev. O œœ O ew O4 ƒ V O w ƒ y y š q. BYZ ƒw v m j yw. Ba Zr 6 Y O +V O +H O Ba Zr 6 Y O 4 +H + Fig. (a) ƒ w v m e. w v m Y1-O1-Zr w O1 wwš w v m Y1-O1- Zr w š Zr-O-Zr4 w O ww ƒ w. v m w w Zr-O-Zr Y1- O4-Zr4 w O O4 v m ww wš, Fig. (a) v m w O w. Fig. (b) ƒ ƒ Ba Zr 6 Y O Y w v m w. Hn On ww v m w. Table Fig. (a) - w ƒ. ƒƒ v m O 1.00 Å ww š, Y-O w (.0,. Å) w Y O Y-O w (. Å) w. Y1-O1-H1 ƒ ƒ 7) 0.0 H1 Y1 ww. w Y1-O4-Zr4 ƒ ƒ 140.0, O4 w H1 w. H Zr4-O-H ƒ ƒ 77. Y1 wwš, Y w š w. Fig. (c) v m w y y. Fig. (c) ùkù Y1-O4-Zr4 Zr-O- Zr4 w O4 O v m w wš v m w, O4 ww v m w O ww v m Zr ww w. w v w wz m O4 ww, O1 v m ww w š, O v m l w. O4 ww v m ƒ¾ O1 w»ƒ q. v m Y1 ew O4 O1 ww» w w y y 0.51 ev. l y y x 0.44 ev e w. 4) 4. BaZrO Y O ƒw O œœ BYZ ƒw v m v w y y w. w BaZrO Y O ƒw Y ƒ w š, O œœ Y l ƒ¾ O ƒ w. ƒ¾ O O œœ ƒ¾ O w y y 0.4 ev ƒ, 1.00 ev j y y. BYZ ƒw v m ƒƒ ƒ¾ O ƒ¾ O ƒ wwš ƒ w, v m w y y 0.51 ev x ew. REFERENCES 1. H. Iwahara, H. Uchida, and S. Tanaka, High Temperature Type Prtn Cnductr Baed n SrCeO and It Applicatin t Slid Electrlyte Fuel Cell, Slid State Inic, 9 [10] (19).. H. Iwahara, H. Uchida, K. On, and K. Ogaki, Prtn Cnductin in Sintered Oxide Baed n BaCeO, J. Electrchem. Sc., 15 [] 59- (19).. K.-D. Kreuer, S. Adam, W. Münch, A. Fuch, U. Klck, and J. Maier, Prtn Cnducting Alkaline Earth Zircnate and Titanate fr High Drain Electrchemical Applicatin, Slid State Inic, 145 [1-4] (001). 4. H. G. Bhn and T. Schber, Electrical Cnductivity f the High-temperature Prtn Cnductr BaZr 0.9 Y 0.1 O.95, J. Am. Ceram. Sc., [4] 76-7 (000). 5. S. M. Haile, G. Staneff, and K. H. Ryu, Nn-tichimetry, Grain Bundary Tranprt and Chemical Stability f Prtn Cnducting Pervkite, J. Mater. Sci., 6 [5] (001). 6. W. G. Cr and D. W. Readey, Prtn Cnductivity Meaurement in Yttrium Barium Cerate by Impedance Spectrcpy, J. Am. Ceram. Sc., 5 [11] (00).

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