The Korean Journal of Ceramics

The Korean Ceramic Society (한국세라믹학회)
권호 표지

Formation Condition and Ferroelectric Properties of Niobate Tetragonal Tungsten Bronze (TTB) Type Ferroelectrics

  • Naoki Wakiya (Department of Metallurgy and Ceramic Science, Graduate School of Seience and Engineering, Tokyo Institute of Technology) ;
  • Wang, Ju-Kai (Department of Metallurgy and Ceramic Science, Graduate School of Seience and Engineering, Tokyo Institute of Technology) ;
  • Kazuo Shinozaki (Department of Metallurgy and Ceramic Science, Graduate School of Seience and Engineering, Tokyo Institute of Technology) ;
  • Nobuyasu Mizutani (Department of Metallurgy and Ceramic Science, Graduate School of Seience and Engineering, Tokyo Institute of Technology)
  • Published : 2000.12.01
Download PDF
⟨ Previous Next ⟩

Abstract

Crystal structure of $Ba_5-5X$Y$_10/3$Nb$_10$O$_30$ was tried to determine by Rietveld analysis using powder X-ray diffraction data. This compound has tetragonal tungsten bronze (TTB) structure with general formula, (Al)$_2$(A2)$_4$(B1)$_2$(B2)$_8$(O1)$_8$(O2)$_8$(O3)$_4$(O4)$_2$(O5)$_4$(O6)$_4$. However, it was difficult to determine the distribution of Ba and Y in Al and A2 sites by the analysis only. Combination of Rietveld analysis and site potentials calculation as well as lattice energy calculations helped to determine the distribution. As the result, it was clarified that $Ba^2+$ cations occupy A2 (pentagonal tunnel site) and $Y^3+$ cations occupy Al (cubic site). The distribution of cations at each site coincides with the distribution estimated by the difference of ionic radii. This supports the formation condition of TTB which was proposed in our previous report. $Ba_5-5X$Y$_10X/3$Nb$_10$O$_30$ shows ferroelectric characteristics. In this compound, remanent polarization decreases slightly with the composition X. On the other hand, the result of crystal structure determination reveals that atomic positions along c-axis for A1, A2, B1 and B2 cations are also decreased with the composition X. This would suggest that the dependence of remanent polarization on composition X is derived by the dependence of atomic coordinates on composition X.

Keywords

References

  1. J. Am. Ceram. Soc. v.45 no.4 Crystal Chemistry of Mixed Bismuth Oxides with Layer-Type Structure E.C.Subbarao
  2. Integrated Ferroelectrics v.12 Laser Ablation Preparation and Property of Bismuth-Layer-Structured SrBi2Ta2O9 and Bi4Ti3O12 Ferroelectric Thin Film M.Okuyama;W.B.Wu;Y.Oishi;Y.Hamakawa
  3. Nature v.374 Fatigue-Free Ferroelectric Capacitors with Platinum Electrodes C.A.Paz deArajo;J.D.Cuchiaro;L.D.McMillan;M.C.Scott;J.F.Scott
  4. J. Am. Ceram. Soc. v.75 no.9 Preparation and Feroelectric Properties of SBN:50 Ceramics S.B.Deshpande;H.S.Potdar;P.D.Godbole;S.K.Date
  5. J. Phys. Soc. Jpn. v.19 no.3 X-ray and Dielectric Studies of the Systems (Ba1-xR2X/3)Nb2O6, Where R is Y, Sm of La K.Masuno
  6. J. Europe.Ceram.Soc. v.19 Synthesis and Dielectric Properties of Ba1-xR2x/3Nb2O6 (R:rare earth) with Tetragonal Tungsten Bronze Structure N.Wakiya;J.K.Wang;A.Saiki;K.Shinozaki;N.Mizutani
  7. Crystallographic Soc.Jpn. Universal Program System for Crystallographic Computation T.Sakurai
  8. The Rietveld Method v.13 F.Izumi;R.A.Young(ed.)
  9. FORTRAN 77 Program to Calculate Electrostatic Site Potentials and Madelung Energies of Ionic Crystals by Fourier Method K.Kato
  10. Acta. Chem. Scand. v.5 Contribution to the Knowledge of the Alkali Tungsten Bronze A.Magneli;B.Blomberg