Effect of nanostructure on the thermal conductivity of La-doped SrTiO3 ceramics |
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| Affiliation: | 1. Institute for Energetics and Interphases, Department of Genoa, National Research Council, Via De Marini 6, 16149 Genoa, Italy;2. Department of Chemistry, University of Pavia, Via Taramelli 12, 27100 Pavia, Italy;3. Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genoa, Italy;4. Institute for Superconductivity, Innovative Materials and Devices, National Research Council, C.so Perrone 24, 16152 Genoa, Italy;5. Department of Science and Engineering of Oxide Materials, Polytechnics University of Bucharest, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest, Romania;6. Institute for Energetics and Interphases, Department of Padova, National Research Council, Corso Stati Uniti 4, 35127 Padova, Italy;1. School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia;2. CSIRO, Clayton, Victoria 3168, Australia |
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| Abstract: | A series of La-doped (10 at.%) SrTiO3 ceramics with grain size ranging from 6 μm to 24 nm was prepared from nanocrystalline powders using high-pressure field assisted sintering (HP-FAST). A progressive reduction of thermal conductivity κ with decreasing grain size was observed. At room temperature, κ of the ceramic with grain size of 24 nm (1.2 W m−1 K−1) is one order of magnitude lower than that of undoped single crystals. The strong suppression of κ can be ascribed to (i) the high concentration of lattice defects, (ii) the increasing contribution of grain boundaries to phonon scattering when the grain size is decreased to the nanoscale and (iii) a moderate amount (10–15 vol.%) of nanopores. These results demonstrate that nanostructuration can be a successful strategy to attain a considerable reduction of κ in heavily doped bulk oxide ceramics. The low electrical conductivity of the La:SrTiO3 nanoceramics represents a major obstacle for thermoelectric applications. |
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| Keywords: | Strontium titanate Thermal conductivity Ceramics Nanostructured materials HP-FAST |
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