Soft X-ray Absorption and Photoemission Spectroscopy Study of Cobalt-Based Thermoelectric Oxides: Ca3Co4O9, Ca3Co2O6, and Bi2Sr2Co2Oy

被引：0

作者：

Kang, J. -S. ^{[1
]}

Lee, H. J. ^{[1
]}

Kim, D. H. ^{[1
]}

Fujii, T. ^{[2
]}

Terasaki, I. ^{[2
]}

Park, H. L. ^{[3
]}

Jeong, Y. H. ^{[3
]}

Min, B. I. ^{[3
]}

机构：

[1] Catholic Univ Korea, Dept Phys, Puchon 420743, South Korea

[2] Waseda Univ, Dept Appl Phys, Tokyo 1698555, Japan

[3] POSTECH, Dept Phys, Pohang 790784, South Korea

来源：

JOURNAL OF ELECTRONIC MATERIALS | 2009年 / 38卷 / 07期

关键词：

XAS; PES; electronic structure; thermopower; cobalt oxides; TRANSITION-METAL COMPOUNDS; MISFIT-LAYERED COBALTITE; SINGLE-CRYSTALS; THERMOPOWER; SYMMETRY; POWER;

D O I：

10.1007/s11664-008-0631-0

中图分类号：

TM [电工技术]; TN [电子技术、通信技术];

学科分类号：

0808 ; 0809 ;

摘要：

The electronic structures of Co-based potential thermoelectric (TE) oxides, including Ca3Co4O9 and Bi(2)Sr(2)Co(2)Oy (y = 8 + delta) single crystals and polycrystalline Ca3Co2O6, have been investigated by employing soft x-ray absorption spectroscopy (XAS) and photoemission spectroscopy (PES). Co 2p XAS measurements show that Co ions are nearly trivalent (Co3+) in all of these Co-based TE oxides with a small mixture of Co4+ ions in Bi2Sr2Co2Oy. Valence-band PES and O 1s XAS measurements show that the occupied Co 3d states are located at the top of the valence bands and that the lowest unoccupied states have the primarily Co 3d character, respectively. These findings suggest the importance of the Co 3d electronic structures in determining TE properties of these Co-based oxides.

引用

页码：1127 / 1131

页数：5

共 30 条

[21] Oxygen nonstoichiometry and cobalt valence in misfit-layered cobalt oxides [J].

Morita, Y ;

Poulsen, J ;

Sakai, K ;

Motohashi, T ;

Fujii, T ;

Terasaki, I ;

Yamauchi, H ;

Karppinen, M .

JOURNAL OF SOLID STATE CHEMISTRY, 2004, 177 (09) :3149-3155

[22]

RARK HL, 2008, THESIS POSTECH

[23] Chemical effects at metal/oxide interfaces studied by x-ray-absorption spectroscopy -: art. no. 214422 [J].

Regan, TJ ;

Ohldag, H ;

Stamm, C ;

Nolting, F ;

Lüning, J ;

Stöhr, J ;

White, RL .

PHYSICAL REVIEW B, 2001, 64 (21)

[24] Laser-excited ultrahigh-resolution photoemission spectroscopy of NaxCoO2•yH2O:: Evidence for pseudogap formation -: art. no. 020505 [J].

Shimojima, T ;

Yokoya, T ;

Kiss, T ;

Chainani, A ;

Shin, S ;

Togashi, T ;

Watanabe, S ;

Zhang, C ;

Chen, CT ;

Takada, K ;

Sasaki, T ;

Sakurai, H ;

Takayama-Muromachi, E .

PHYSICAL REVIEW B, 2005, 71 (02)

[25] Contribution of electronic structure to the large thermoelectric power in layered cobalt oxides [J].

Takeuchi, T ;

Kondo, T ;

Takami, T ;

Takahashi, H ;

Ikuta, H ;

Mizutani, U ;

Soda, K ;

Funahashi, R ;

Shikano, M ;

Mikami, M ;

Tsuda, S ;

Yokoya, T ;

Shin, S ;

Muro, T .

PHYSICAL REVIEW B, 2004, 69 (12)

[26] Large thermoelectric power in NaCo2O4 single crystals [J].

Terasaki, I ;

Sasago, Y ;

Uchinokura, K .

PHYSICAL REVIEW B, 1997, 56 (20) :12685-12687

[27] Thermoelectric materials, phenomena, and applications: A bird's eye view [J].

Tritt, TM ;

Subramanian, MA .

MRS BULLETIN, 2006, 31 (03) :188-194

[28] THE 2P ABSORPTION-SPECTRA OF 3D TRANSITION-METAL COMPOUNDS IN TETRAHEDRAL AND OCTAHEDRAL SYMMETRY [J].

VANDERLAAN, G ;

KIRKMAN, IW .

JOURNAL OF PHYSICS-CONDENSED MATTER, 1992, 4 (16) :4189-4204

[29] Nature of magnetism in Ca3Co2O6 -: art. no. 186401 [J].

Wu, H ;

Haverkort, MW ;

Hu, Z ;

Khomskii, DI ;

Tjeng, LH .

PHYSICAL REVIEW LETTERS, 2005, 95 (18)

[30] Orbital symmetry and electron correlation in NaxCoO2 -: art. no. 146402 [J].

Wu, WB ;

Huang, DJ ;

Okamoto, J ;

Tanaka, A ;

Lin, HJ ;

Chou, FC ;

Fujimori, A ;

Chen, CT .

PHYSICAL REVIEW LETTERS, 2005, 94 (14)

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