Effect of cation stoichiometry on the transport properties of calcium ruthenium oxide ceramics
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Seebeck coefficient and electrical resistivity have been determined on a series of compounds having the general composition CanRu1−nOy. From property and structural considerations, these compounds have been divided into two categories: one group resembling Ca2RuO4 and the second category exhibiting properties similar to CaRuO3. While the former is an antiferromagnetic insulator, the latter is a paramagnetic metal. The Seebeck coefficient remains relatively unchanged within the members of the two groups, irrespective of the molar ratios of the cations. Even between the two groups of compounds, the Seebeck coefficient exhibits minimal difference even as the cation ratio (Ru/Ca) of the compounds is varied from 0.35 (n = 0.74) to 1.94 (n = 0.34). The resistivity, however, varies by nine orders of magnitude as the cation ratio is varied in the same range. Consequently, the resulting power factor (s2σ, where s is the Seebeck coefficient and σ is the electrical conductivity), which is a measure of the usefulness or thermopower conversion efficiency of a thermoelectric material, is found to vary by nine orders of magnitude.
KeywordsPower Factor RuO2 Seebeck Coefficient Thermoelectric Material Insulator Transition
We gratefully acknowledge the contributions of Niveen Fahmy and Wei Zhao in sample preparation.
- 9.Rane S, Prudenziati M, Morten B (2005). J Active Passive Elec Dev 1:123Google Scholar
- 16.Gibb TC, Greatrex RG et al (1973) J Chem Soc, Dalton Trans 1253. doi: https://doi.org/10.1039/dt9730001253
- 22.Raveau B, Maignan A (2003) Europhys News 34(6)Google Scholar
- 23.Hebert S, Martin C et al (2001) Proceedings of the 6th European workshop on thermoelectrics, FreiburgGoogle Scholar
- 24.Van der Pauw LJ (1958) Philips Res Rep 13:1Google Scholar
- 25.Mott NF, Davis EA (1979) Electronic processes in non-crystalline materials. Clarendon Press, LondonGoogle Scholar