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Thermoelectric Properties of Al4C3-doped α-SiC

Al4C3 첨가 α-SiC의 열전변환특성

  • 박영석 (인천대학교 신소재공학과) ;
  • 배철훈 (인천대학교 신소재공학과)
  • Published : 2003.10.01

Abstract

The effect of A1$_4$C$_3$ additive on the thermoelectric properties of SiC ceramics were studied. Porous SiC ceramics with 47∼59% relative density were fabricated by sintering the pressed $\alpha$-SiC powder compacts with A1$_4$C$_3$at 2100∼220$0^{\circ}C$ for 3 h in Ar atmosphere. Crystalline phases of the sintered bodies were identified by powder X-Ray Diffraction (XRD) and their microstructures were observed with a Scanning Electron Microscope (SEM). In the case of A1$_4$C$_3$ addition, the phase transformation of 6H-SiC to 4H-SiC could be observed during sintering. The Seebeck coefficient and electrical conductivity were measured at 550∼95$0^{\circ}C$ in Ar atmosphere. In the case of undoped specimens, the Seebeck coefficients were positive (p-type semiconducting) possibly due to a dominant effect of the acceptor impurities (Al, Fe) contained in the starting powder and electrical conductivity increased as increasing sintering temperature. Electrical conductivity of A1$_4$C$_3$doped specimen is larger than that of undoped specimen under the same condition, which might be due to the reverse phase transformation and increasing of carrier density. And the Seebeck coefficient of A1$_4$C$_3$ doped specimen is also larger than that of undoped specimen. The density of specimen, the amount of addition and sintering atmosphere had significant effects on the thermoelectric property.

SiC세라믹스의 열전변환물성에 미치는 A1$_4$C$_3$ 첨가효과에 대해 연구하였다. $\alpha$-SiC 분말에 A1$_4$C$_3$를 첨가하여 Ar분위기 2100∼220$0^{\circ}C$에서 3시간 소결하여 상대밀도 47∼59%인 다공질 SiC세라믹스를 제조하였다. X-선 회절분석 및 주사형 전자현미경으로 소결체의 상조성과 미세구조를 분석하였으며, A1$_4$C$_3$ 첨가에 의해 6H에서 4H로의 상전이 발생을 관찰할 수 있었다. 전기전도도와 Seebeck 계수를 Ar 분위기 550∼95$0^{\circ}C$에서 측정하였다. 무첨가 시료의 경우 출발원료중에 함유된 p형 불순물(Al, Fe)에 의해 Seebeck 계수가 정(+)의 값을 나타내었으며, 소결온도가 증가함에 따라 전기전도도가 증가하였다. A1$_4$C$_3$ 첨가 시료의 전기전도도는 상전이 및 캐리어농도 증가에 의해 무첨가 시료보다 높았으며, 또 Seebeck 계수도 크게 나타났다. 시료의 밀도, 첨가량 및 소결조건이 열전변환물성에 크게 기여하였다.

Keywords

References

  1. Modern Thermoelectrics D.M.Rowe;C.W.Bhandari
  2. Thermoelectric Materials and Devices I.B.Cadoff;E.Miller
  3. Thermoelectric Semiconductors and their Applications K.Uemura;I.Nishida
  4. Proceeding of the 8th International Conference on Thermoelectric Energy Conversion (nancy) Microstructure-controlled Porous SiC Ceramics for High-temperature Thermoelectric Energy Conversion K.Koumoto;C.H.Pai;S.Takeda;H.Yanagida
  5. Thermoelectric semiconductors Y.Suga(ed.)
  6. J. Appl. Phys. v.46 no.12 The Electrical Properties of Polycrystalline Sillion Films J.Y.W.Seto https://doi.org/10.1063/1.321593
  7. J. Appl. Phys. v.47 no.9 Zero-bias Resistance of Grain Boundaries in Neuron-reansmutation-doped Polycrystalline C.H.Seager;T.G.Castner
  8. J. Appl. Phys. v.49 no.7 Carrier Transport in Oxygen-rich Polycrystalline Silicon Films M.L.Tarng https://doi.org/10.1063/1.325367
  9. J. Appl. Phys. v.49 no.11 Transport Properties of Polycrystalline Silicon Films G.Baccarani;B.Ricco;G.Spadini https://doi.org/10.1063/1.324477
  10. J. Appl. Phys. v.53 no.1 Electrical Properties of Lightly Doped Polycrystalline Silicon J.Y.M.Lee;I.C.Cheng
  11. J. Appl. Phys. v.48 no.10 The Physics of Zinc Oxide Varistors P.R.Emtage https://doi.org/10.1063/1.323391
  12. J. Appl. Phys. v.49 no.5 Conduction Mechanism of Non-ohmic Zinc Oxide Ceramics K.Eda https://doi.org/10.1063/1.325139
  13. J. Ceram. Soc. Jpn. v.99 no.12 Effects of additives on the Stacking fault Annihilation in β-SiC Powder Compacts W.S.Seo;C.H.Pai;K.Koumoto;H.Yanagida https://doi.org/10.2109/jcersj.99.1179
  14. Miner. J. v.4 Silicon Carbide Crystals Grown in Nitrogen Atmosphere T.Kawamura https://doi.org/10.2465/minerj1953.4.333
  15. Mater. Res. Bull. v.4 The Influence of Impurities on the Growth of Silicon carbide by Recrystallization W.F.Knippenberg;G.Verspui https://doi.org/10.1016/0025-5408(69)90015-4
  16. J. Ceram. Soc. Jpn. v.78 no.7 The Effect of Doped Aluminium on Thermal stability of 4H-and 6H-SiC M.Mitomo;Y.Inomata;M.Kumanomido
  17. J. Am. ceram. Soc. v.64 The 6H-3C Reverse Transformation in Silicon Carbide Compacts N.W.Jepps;T.F.Page
  18. J. Ceram. Soc. Jpn. v.97 no.10 Effects of Sintering additives on the Thermoelectric Properties of SiC Ceramics C.H.Pai;K.Koumoto;H.Yanagida https://doi.org/10.2109/jcersj.97.1170
  19. Silicon Carbide v.17 no.a V.Munch