Phase Relations in the ZrO2-Y2O3-La2O3 System at 1250 °C


Article Preview

Phase equilibria in the ternary system ZrO2-Y2O3-La2O3 at 1250 °C have been studied and isothermal section have been developed. Fine chemical technique such as co-precipitation was used to obtain ceramic nanopowders (with average particle size of 8-20 nm) available for nonisothermal sintering as well. The phase compositions of the annealed samples were studied by methods of X-ray analysis at 20 °C, petrographic and electron microprobe X-ray analyses. No ternary compounds were found. The phase equilibria in the system are determined by intermediate phases: La2Zr2O7 and LaYO3 that crystallize in the pyrochlore and perovskite-type structures, respectively. Solid solutions based on the constituent oxides such as tetragonal (T) and cubic fluorite-type structure (F) ZrO2, cubic form of rare-earth oxides (C-type) Y2O3,as well as hexagonal (A) and monoclinic (B) forms La2O3 were found at 1250 °C. The nanocrystalline powders of tetragonal zirconia actively sintered on heating up to 1150-1400 °C and the powders of lanthanum zirconate show active densification on heating up to 1550-1650 °C. The electrical properties (at 600-950 °C) of yttria-doped pyrochlore were measured, the highest conductivity has been revealed at 10 mol % Y2O3.



Edited by:

Dragan P. Uskokovic, Slobodan K. Milonjic and Dejan I. Rakovic




E.R. Andrievskaya and V.P. Red'ko, "Phase Relations in the ZrO2-Y2O3-La2O3 System at 1250 °C ", Materials Science Forum, Vol. 518, pp. 343-348, 2006

Online since:

July 2006




[1] N.Q. Minh: J. Amer. Ceram. Soc. Vol. 76 (1993), p.563.

[2] N.Q. Minh and T. Takahashi: Science and Technology of Ceramic Fuel Cells (Elsevier 1995), p.1.

[3] A. Eastman, U.S. Choi, S. Li, G. Soyez, L.J. Thompson and R.J. DiMelfi: Novel Applications Exploiting the Thermal Properties of Nanostructured Materials (Proc. of the Conference Fine, Ultrafine and Nano Powders'98, November 8-10, New York 1998).

[4] W.P. Parks, W.Y. Lee and I.G. Wright: Processings of the Thermal Barrier Coating (Workshop, Westlake, OH, DOE Report Conf. - 9503150-1 1995).

[5] G.A. Kool: J. Thermal Spray Technol. Vol. 5 (1996), p.31.

[6] S. Raghavan, H. Wang, R.B. Dinwiddie and M.J. Mayo: Scripta Materialia Vol. 39 (1998), p.1119.

[7] R. Vassen, F. Tietz and J. Kerkhoff: J. Amer. Ceram. Soc. Vol. 82 (1999).

[8] J. -H. Lee, S.M. Yoon, B. -K. Kirn, J. Kim, H. -W. Lee and H. -S. Song: Solid State Ionics Vol. 144 (2001), p.175.

[9] M.F. Trubelja and V.S. Stubican: J. Amer. Ceram. Soc. Vol. 71 (1988), p.662.

[10] A.V. Shevchenko, L.M. Lopato et al.: Izv. AN SSSR Neorg. Mater. Vol. 23 (1987), p.452.

[11] A.V. Shevchenko, V.D. Tkachenko et al.: Powder Metallurgy (Rus) Vol. 1 (1986), p.91.

[12] A. Rouanet: Review Intern. Hautes Temper. et Refract. Vol. 8 (1971), p.161.

[13] L.M. Lopato, B.S. Nigmanov et al.: Izv. AN SSSR Neorg. Mater. Vol. 22 (1986), p.678.

[14] M.J. Readey, R. -R. Lee, J.W. Halloran, et al.: J. Am. Ceram. Soc. Vol. 73 (1990), p.1499.

[15] D.C. Hague: Master Thesis (Pennsylvania State Univ., USA 1992).

[16] P. Duran, M. Villegas, I.F. Fernandez, et al.: Materials Science and Engineering A Vol. 232 (1997), p.168.

[17] P. Duran, M. Villegas, I.F. Fernandez, et al.: J. Materials Science Letters Vol. 15 (1996), p.741.

[18] L.M. Navarro, P. Recio and P. Duran: J. Materials Science Vol. 30 (1995), p. (1931).

[19] S. Meilicke and S. Haile: Mat. Res. Soc. Proc. Vol. 393 (1995), p.55.