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Powder Metallurgy and Metal Ceramics

, Volume 45, Issue 1–2, pp 59–71 | Cite as

Phase equilibria in the system HfO2-Y2O3-La2O3 AT 1900°C

  • E. R. Andrievskaya
  • L. M. Lopato
  • V. P. Smirnov
Physicochemical Materials Research

Abstract

We have used x-ray phase analysis, electron-probe microanalysis, petrography, and electron microscopy on annealed specimens to study phase equilibria in the ternary system HfO2-Y2O3-La2O3 at 1900 °C over the entire concentration range. We have plotted the isothermal cross section of the phase diagram for this system at the indicated temperature. We found 23 phase regions. A typical feature of the system is formation of solid solutions based on different crystal modifications of the starting components (A-and H-La2O3, C-Y2O3, T-and F-HfO2) and also the compounds La2Hf2O7, LaYO3. We did not observe new phases in the system. The nature of the phase equilibria in the system is consistent with the high relative thermodynamic stability of lanthanum hafnate (ΔH °La2Hf2O7 ≈ 100 kJ/mole) compared with LaYO3. We established that adding a third component extends the thermal stability region for the ordered phase of LaYO3 toward higher temperatures.

Keywords

phase equilibria hafnium oxide yttrium oxide lanthanum oxide isothermal cross section solid solution ordered phase pyrochlore type phase phase diagram of a ternary system 

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References

  1. 1.
    J. Wang, R. Stevens, and H. P. Li, “Review of hafnia and hafnia-toughened ceramics,” J. Mat. Sci., 27, 5397–5430 (1992).CrossRefGoogle Scholar
  2. 2.
    H. Shiromizu and N. Morita, “Properties, areas of application, and prospects for development of technical ceramic,” Seidenki Gakkaishi, Proc. Inst. Electrost. Jpn., 10, No. 6, 426–429 (1986).Google Scholar
  3. 3.
    I. Hiroyuki, I. Naboru, T. Hiroshi, et al., Material for a Seal between Ceramic Pieces, Ceramic and Metal, Pat. 58-41766 Japanese, Publ. 1981.Google Scholar
  4. 4.
    E. R. Andrievskaya, L. M. Lopato, V. V. Kovylyaev, and Z. A. Zaitseva, “Phase equilibria in the ternary system HfO2-Y2O3-La2O3,” Neorg. Mater., 32, No. 6, 727–735 (1996).Google Scholar
  5. 5.
    E. R. Andrievskaya, L. M. Lopato, V. P. Smirnov, and I. E. Kir’yakova, “Isothermal cross section of the phase diagram for the system HfO2-Y2O3-La2O3 at 1600°C,” Poroshk. Metall., Nos. 7–8, 147–158 (1996).Google Scholar
  6. 6.
    E. R. Andrievskaya, L. M. Lopato, and I. E. Kir’yakova, “Solid-phase transformations in the systems HfO2-Y2O3-Ln2O3 (Ln = La, Er): model and experiment,” in: Physical Materials Science and the Physicochemical Principles for Design of New Materials [in Russian], V. V. Skorokhod (ed.), Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Kiev (1994), pp. 85–95.Google Scholar
  7. 7.
    E. R. Andrievskaya, L. M. Lopato, and A. V. Shevchenko, “Phase transformations in the ternary systems HfO2(ZrO2)-Y2O3-La2O3(Er2O3),” in: Proceedings, Fourth European Ceramic Society Conference on Basic Science in Processing of Advanced Ceramics (October 2–6, 1995, Italy), Faenza (1995), Vol. 2, pp. 431–439.Google Scholar
  8. 8.
    J. Coutures and M. Foex, “High temperature study of the phase diagram of the system formed by yttrium sesquioxide,” J. Solid State Chem., 11, No. 4, 294–300 (1974).Google Scholar
  9. 9.
    J. Coutures, F. Sibieude, and M. Foex, “High temperature study of systems formed by lanthanum sesquioxides with lanthanide sesquioxides. II. Effect of quenching on the nature of the phases obtained at room temperature,” J. Solid State Chem., 17, No. 4, 377–384 (1976).Google Scholar
  10. 10.
    M. Mizuno, A. Rouanet, T. Yamada, and T. Noguchi, “Phase diagram of the system La2O3-Y2O3 at high temperature,” J. Ceram. Soc. Japan, 84, No. 7, 342–347 (1976).Google Scholar
  11. 11.
    L. M. Lopato, B. S. Nigmanov, A. V. Shevchenko, and Z. A. Zaitseva, “Reaction of lanthanum oxide with yttrium oxides,” Izv. Akad. Nauk SSSR, Neorg. Mater., 22, No. 5, 771–774 (1986).Google Scholar
  12. 12.
    G. C. Wei, T. Emma, and W. H. Rhodes, “Analytical microscopy study of phases and fracture in Y2O3-La2O3 alloys,” J. Amer. Ceram. Soc., 71, No. 10, 820–825 (1988).CrossRefGoogle Scholar
  13. 13.
    J. Coutures, A. Rouanet, R. Verges, and M. Foex, “High temperature study of systems formed by lanthanum sesquioxide and lanthanide sesquioxides. I. Phase diagrams (1400°C < T < T liquid),” J. Solid State Chem., 17, No. 1–2, 172–182 (1976).Google Scholar
  14. 14.
    V. Berndt, D. Maier, and C. Keller, “New A‴B‴O3 interlanthanide perovskite compounds,” J. Solid State Chem., 13, No. 1–2, 131–135 (1975).CrossRefGoogle Scholar
  15. 15.
    W. H. Rhodes, “Controlled transient solid second phase sintering of yttria,” J. Amer. Ceram. Soc., 64, No. 1, 13 (1981).Google Scholar
  16. 16.
    P. Duran, “Phase relationships in the systems HfO2-La2O3 and HfO2-Nd2O3,” Ceram. Intern., 1, No. 1, 10–13 (1975).CrossRefGoogle Scholar
  17. 17.
    A. V. Shevchenko and L. M. Lopato, “Effect of hafnium dioxide on the polymorphism of lanthanoid oxides,” Dop. AN UkrSSR, Ser. B, No. 8, 737–739 (1975).Google Scholar
  18. 18.
    É. L. Karyakina, E. I. Zoz, A. M. Gavrish, and N. V. Gul’ko, “Some crystal chemistry and thermophysical characteristics of lanthanum zirconate and hafnate,” Zhurn. Neorg. Khim., 23, No. 12, 3202–3205 (1978).Google Scholar
  19. 19.
    A. V. Shevchenko and L. M. Lopato, “Effect of lanthanoid oxides of the cerium subgroup on the polymorphism of hafnium dioxide,” Dop. AN UkrSSR, Ser. B, No. 8, 718–721 (1977).Google Scholar
  20. 20.
    A. V. Shevchenko, L. M. Lopato, A. I. Stegnii, et al., “Liquidus of hafnium dioxide — rare earth oxide systems in the high HfO2 content region,” Izv. Akad. Nauk SSSR, Neorg. Mater., 17, No. 6, 1022–1020 (1981).Google Scholar
  21. 21.
    A. V. Shevchenko, L. M. Lopato, and Z. A. Zaitseva, “Reaction of HfO2 with lanthanum, praseodymium, and neodymium oxides at high temperatures,” Izv. Akad. Nauk SSSR, Neorg. Mater., 20, No. 9, 1530–1534 (1984).Google Scholar
  22. 22.
    V. B. Glushkova, M. V. Kravchinskaya, A. K. Kuznetsov, and P. A. Tikhonov, Hafnium Dioxide and Its Compounds with Rare Earth Oxides [in Russian], Nauka, Leningrad (1984).Google Scholar
  23. 23.
    A. V. Shevchenko, L. M. Lopato, and I. E. Kir’yakova, “Reaction of HfO2 with Y2O3, Ho2O3, Er2O3, Tm2O3, Yb2O2, and Lu2O3 at high temperatures,” Izv. Akad. Nauk SSSR, Neorg. Mater., 20, No. 12, 1991–1996 (1984).Google Scholar
  24. 24.
    M. F. Trubelja and V. S. Stubican, “Phase equilibria and ordering in the system Zirconia-Hafnia-Yttria,” J. Amer. Ceram. Soc., 71, No. 8, 662–666 (1988).CrossRefGoogle Scholar
  25. 25.
    P. A. Arsen’ev, V. B. Glushkova, et al., Compounds of Rare Earth Elements. Zirconates, Hafnates, Niobates, Tantalates, Antimonates [in Russian], Nauka, Moscow (1985).Google Scholar
  26. 26.
    V. K. Pecharskii, P. Yu. Zavalii, L. G. Ansel’rud, et al., “Structural analysis software package for the UVKSM-4,” Vest. L’vov. Univ., Ser. Khim., No. 25, 9–11 (1984).Google Scholar
  27. 27.
    L. H. Ahrens, “Use of ionization potentials. I. Ionic radii of the elements,” Geochem. Cosmochim. Acta, No. 2, 155–158 (1952).Google Scholar

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • E. R. Andrievskaya
    • 1
  • L. M. Lopato
    • 1
  • V. P. Smirnov
    • 1
  1. 1.Institute for Problems of Materials ScienceNational Academy of Sciences of UkraineKiev

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