Advertisement

Journal of Electroceramics

, Volume 22, Issue 1–3, pp 120–124 | Cite as

Eliminating chemical effects from thermal expansion coefficient measurements

Article

Abstract

A new approach for measuring coefficient of thermal expansion (CTE) in materials that exhibit chemical expansion as well is introduced. This allows separating the expansion that is induced by temperature changes alone from the total expansion, which is induced by temperature and chemical changes in the material. Combining this with measurements that are done at constant temperature and in controlled oxygen environment can yield better understanding of the subject of solid expansion in oxides. In order to understand whether the oxygen partial pressure has an influence on the CTE or not, measurements were carried out on three different oxide materials at several oxygen activities. A comparison between SrTiO3, SrZrO3 and Al2O3 was done by a single push-rod dilatometer equipped with a system that allows purging with different gas mixtures and a pO2 monitoring device. In order to make the experiment within a reasonable timeframe, very porous samples have been used. The experiments were done at three different temperatures: 722, 822 and 1022 °C. The pO2 was controlled by CO–CO2–Ar gas mixture, and monitored with an in house built zirconia sensor. The main results reveal that the CTE of the perovskites is influenced by the pO2 while that of alumina, as expected, is not. The CTE of SrTiO3 is more sensitive to changes in the pO2 than that of SrZrO3. In some of the measurements there exists a clear change of the behavior of the CTE vs. log(pO2) at a certain oxygen partial pressure.

Keywords

Thermal expansion Dilatometry Chemical expansion Perovskites Modulated temperature 

Notes

Acknowledgements

Discussions with Profs. Ya. Kraftmakher of Bar Ilan University, I. Lubomirski of the Weizmann Institute of Science and L. Gauckler and his group members at ETH Zürich are greatly appreciated. The financial support of the Morantz Energy Research Fund and the Russell Berry Nanotechnology Institute are thankfully acknowledged.

References

  1. 1.
    R.E. Newnham, Properties of Materials: Anisotropy, Symmetry, Structure (Oxford University Press, New York, 2005)Google Scholar
  2. 2.
    J.F. Nye, Physical Properties of Crystals: Their Representation by Tensors and Matrices, 2nd edn. (Oxford University Press, New York, 1985)Google Scholar
  3. 3.
    B.C.H. Steele, Oxygen-transport and exchange in oxide ceramics J. Power Sources 49(1–3), 1–14 (1994)CrossRefADSGoogle Scholar
  4. 4.
    A. Bieberle, L.J. Gauckler, in Thermal and isothermal expansion, ed. by H.L. Tuller, J. Schoonman, I. Riess. Oxygen Ion and Mixed Conductors and their Technological Applications, vol. 368 (Kluwer, Dordrecht, 2000), pp. 347–358Google Scholar
  5. 5.
    J. Larminie, A. Dicks, Fuel Cell Systems Explained, 2nd edn. (Wiley, Sussex, 2003), p. 428Google Scholar
  6. 6.
    M. Mori, Effect of B-site doping on thermal cycle shrinkage for \({\text{La}}_{0.8} {\text{Sr}}_{0.2} {\text{Mn}}_{1 - x} {\text{M}}_x {\text{O}}_{3 + \delta } \) perovskites (M=Mg, Al, Ti, Mn, Fe, Co, Ni) Solid State Ionics 174, 1–8 (2004)CrossRefGoogle Scholar
  7. 7.
    X.Y. Chen, J.S. Yu, S.B. Adler, Thermal and chemical expansion of Sr-doped lanthanum cobalt oxide (\({\text{La}}_{1 - x} {\text{Sr}}_{\text{x}} {\text{CoO}}_{3 - \delta } \)) Chem. Mater. 17, 4537–4546 (2005)CrossRefGoogle Scholar
  8. 8.
    V.V. Kharton, A.A. Yaremchenko, M.V. Patrakeev, E.N. Naumovich, F.M.B. Marques, Thermal and chemical induced expansion of \({\text{La}}_{0.3} {\text{Sr}}_{0.7} \left( {{\text{Fe,Ga}}} \right){\text{O}}_{3 - \delta } \) ceramics J. Eur. Ceram. Soc. 23(9), 1417–1426 (2003)CrossRefGoogle Scholar
  9. 9.
    S. Hashimoto, L. Kindermann, P.H. Larsen, F.W. Poulsen, M. Mogensen, Conductivity and expansion at high temperature in \({\text{Sr}}_{0.7} {\text{La}}_{0.3} {\text{TiO}}_{3 - \alpha } \) prepared under reducing atmosphere J. Electroceram. 16(2), 103–107 (2006)CrossRefGoogle Scholar
  10. 10.
    M. Mori, Y. Hiei, Thermal expansion behavior of titanium-doped La(Sr)CrO3 solid oxide fuel cell interconnects J. Am. Ceram. Soc. 84(11), 2573–2578 (2001)CrossRefGoogle Scholar
  11. 11.
    Y. Kraftmakher, Modulation calorimetry and related techniques Phys. Reps. 356, 1–117 (2002)CrossRefADSGoogle Scholar
  12. 12.
    T.H. Johansen, An ac-dilatometer for thermal expansivity measurements High Temp. High Press. 19, 77–87 (1987)Google Scholar
  13. 13.
    I. Riess, O. Porat, Oxygen partial-pressure measurements under more demanding conditions Solid State Ionics 86–8, 1075–1078 (1996)CrossRefGoogle Scholar
  14. 14.
    R.D. Levi, Y. Tsur, The effect of oxygen vacancies in the early stages of BaTiO3 nanopowder sintering Adv. Mater. 17(13), 1606–1608 (2005)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Chemical Engineering DepartmentTechnion, Israel Institute of TechnologyHaifaIsrael

Personalised recommendations