Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
권호 표지

Defect Chemistry of Ca and Nb doped $BaTiO_3$

Ca와 Nb가 첨가된 $BaTiO_3$의 결함화학

  • Jeong, Jae-Ho (Dept.of Inorganic Materials Engineering,Seoul National University) ;
  • Han, Yeong-Ho (Sung Kyun Kwan University Dept.of Materials Engineering) ;
  • Park, Sun-Ja (Dept.of Inorganic Materials Engineering,Seoul National University)
  • 정재호 (서울대학교 무기재료공학과) ;
  • 한영호 (성균관대학교 재료공학과) ;
  • 박순자 (서울대학교 무기재료공학과)
  • Published : 1994.10.01
Download PDF
⟨ Previous Next ⟩

Abstract

The increase in the resistance of $BaTio_{3}$ with addition of Ca is attributed to the formation ofthe acceptor impurity by $CaCa^{2+}$" which substitutes Ti4+. However, some authors suggested that $Ca^{2+}$ can not substitute $Ti^{4+}$ because of its larger ionic radius. In this work, the existence of acceptor by Ca hasbeen studied through the high temperature equilibrium electrical conductivity of $BaTiO_{3}$ codoped with Caand Nb, where Ba/(Ti+Ca+Nb) was kept equal to unity. It was measured at $1000^{\circ}C$, and the oxygenpartial pressure was controlled between $10^{-15}$ ~ 1 atm. Changing the amount of added Ca and Nbresulted in the compensation effect between donor and acceptor, i.e., Nb was compensated by the acceptor.And through the defect chemical interpretation of the measured data, it was concluded that Ti canbe substitued with Ca. The existence of such acceptor was reaffirmated by ICTS(Isotherma1 CapacitanceTransient Spectroscopy) measurements.oscopy) measurements.

$BaTio_{3}$에 Ca가 첨가되면 상온 저항을 증가시키며 이는 $Ca^{2+}$가 $Ti^{4+}$를 치환하여 acceptor 불순물을 형성하기 때문이라고 생각된다. 그러나 $Ca^{2+}$는 $Ti^{4+}$보다 이온 반경이 크므로 그 자리를 치환하지 않는다는 주장도 있다. 본 실험에서는 $BaTiO_{3}$에 의한 acceptor가 존재하는지 알아보기 위하여 Ba/(Ti+Ca+Nb)=1이 되도록 Ca와 Nb를 첨가하여 산소 분압의 변화에 따른 고온 평형 전기 전도도를 측정하였다. 측정은 $1000^{\circ}C$에서 행하였으며 산소 분압은 $10^{-15}$ ~ 1 기압의 범위에서 조절하였다. 첨가된 Ca와 Nb의 농도를 변화시킨 결과, acceptor와 donor의 상호 보상 효과가 나타났다. 즉, Nb에 의한 donor를 보상하는 acceptor가 존재함을 확일하였고, 전도도 곡선의 결함 화학적인 해석에 의하여 Ca가 Ti자리를 치환함을 알았다. 이러한 acceptor의 존재는 ICTS에 의해서도 확인되었다.

Keywords

References

  1. Philips Technical Review v.38 no.3 The PTC Effect of Barium Titanate J. Daniels;K. H. Hardtl;R. Wernicke
  2. J. Am. Ceram. Soc v.73 no.3 Electrical Properties of PTCR Barium Titantate D. Y. Wang;K. Umeya
  3. J. Am. Ceram. Soc v.68 no.10 PCTR Effect in BaTiO₃ G. V. Lewis;C.R.A Catlow
  4. Am. Ceram. Soc. Bull v.57 no.6 Ceramic Disk Capacitors with Base-Metal Electrode I. Burn
  5. Am. Ceramic. Soc. Bull v.66 no.9 Dielectric Materials for Base-Metal Multilayer Ceramic Capacitors Y. Sakabe
  6. J. Appl. Phys v.67 no.2 Influence of CaO Addition on the Electrical Properties of BaTiO₃Ceramics T. F. Lin;C. T. Hu
  7. J. Mater. Sci v.26 The Microstructure Development and Electrical Properties of Calcium-Modified Barium Ta Ceramics T. F. Lin;J. L. Lin;C. T. Hu;I. N. Lin
  8. J. Am. Ceram. Soc v.70 no.2 Defect Chemistry of BaTiO₃with Additions of CaTiO₃ X. W. Zhang
  9. J. Am. Ceram. Soc v.70 no.2 Calcium as an Acceptor Impurity in BaTiO₃ Y. H. Han;J. B. Appleby;D. M. Smyth
  10. 한국재료학회지 v.2 no.4 ATiO₃단순 페롭스카이트 결함구조 한영호
  11. J. Electrochem. Soc. v.123 no.10 Defect Chemistry of BaTiO₃ N. H. Chan;D. M. Smyth
  12. J. Am. Ceram. Soc v.64 no.9 Nonstoichiometry in Undoped BaTiO₃ N. H. Chan;R. K. Sharma;D. M. Smyth
  13. J. Am. Ceram. Soc v.54 no.10 Ti-Rich Nonstoichiometric BaTiO₃:I, High Temperature Electrical Conductivity Measurements S. A. Long;R. N. Blumenthal
  14. J. Am. Ceram. Soc v.54 no.11 Ti-Rich Nonstoichiometric BaTiO₃:Ⅱ, Analysis of Defect Structure S. A. Long;R. N. Blumenthal
  15. J. Am. Ceram. Soc v.71 no.4 Defect Structure and Electrical Properties of Single Crystal $Ba_{0.03}Sr_{0.97}TiO_3$ G. M. Choi;H. L. Tuller
  16. J. Electrochem. Soc v.128 no.8 Nonstoichiometry in SrTiO₃ N. H. Chan;R. K. Sharma;D. M. Smyth
  17. J. Solid State Chem v.39 Electrical Conductivity in Strontium Titanate U. Balachandran;N. G. Eror
  18. J. Solid State Chem v.42 Electrical Conductivity in Strontium Titanate with Nonideal Cationic Ratio N. G. Eror;U. Balachandran
  19. J. Solid State Chem v.41 Electrical Conductivity in Calcium Titanate U. Balachandran;B. Odekik;N. G. Eror
  20. Mater. Sci. Enginer v.54 Electrical Conductivity in Calcium Titanate with Excess CaO U. Balachandran;N. G. Eror
  21. J. Solid State Chem v.43 On the Defect Structure of Calcium Titanate with Nonideal Cationic Ratio N. G. Eror;U. Balachandran
  22. J. Solid State Chem v.6 no.1 Point Defects in Reduced Strontjum Titanate H. Yamada;g. R. Miller
  23. J. Am. Ceram. Soc v.65 no.3 Nonstoichiometry in Acceptor-Doped BaTiO₃ N. H. Chan;R. K. Sharma;D. M. Smyth
  24. Philips Res.Repts v.31 Defect Chemistry and Electrical Conductivity of Doped Barium Titanate;I,Electrical Conductivity at High Tmeperature of Donor-Doped Barium Titanate Ceramics J. Daniels;K. H. Hardtl
  25. M.S.Thesis The Effect of Sr/Ti Ratio and Additives on the Microstructure and Electrical Conductivity of SrTiO₃ S. R. Wite
  26. J. Am. Ceram. Soc v.67 no.4 Non-stoichiometry in Donor-Doped BaTiO₃ N. H. Chan;D. M. Smyth
  27. U.S.Pat.No.3330607 Method of Preparing Lead and Alkaline Earth Titanates and Niobates and Coatings Using the Same to Form a Capacitor M. Pechini
  28. Jpn. J. Ceram. Soc v.97 no.10 Detection and characterization of Trap Centers in ZnO Varistors by ICTS T. Maeda;M. Takata
  29. Jpn. J. Appl. Phys v.19 no.6 Isothermal Capacitance Transient spectroscopy for Determination of Deep Level Parameters H. Okushi;Y. Tokumaru