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Thermal conductivity of electron-doped CaMnO3 perovskites / Yang Wang in Acta materialia, Vol. 58 N° 19 (Novembre 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6306–6316 Titre : Thermal conductivity of electron-doped CaMnO3 perovskites : Local lattice distortions and optical phonon thermal excitation Type de document : texte imprimé Auteurs : Yang Wang, Auteur ; Yu Sui, Auteur ; Xianjie Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 6306–6316 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Manganite  perovskite  Thermal  conductivity  Spin-phonon  scattering  MnO6  distortion  Optical  phonon Résumé : The thermal transport properties of a series of electron-doped CaMnO3 perovskites have been investigated. Throughout the temperature range 5–300 K, phonon thermal conductivity is dominant, and both electron and spin wave contributions are negligible. The short phonon mean free paths in this system result in the relatively low thermal conductivities. The strong phonon scatterings stem from the A-site mismatch and bond-length fluctuations induced by local distortions of MnO6 octahedra. The thermal conductivity in the magnetically ordered state is enhanced as a result of the decrease in spin–phonon scattering. The results also indicate that above the magnetic ordering temperature, observable thermal excitation of optical phonons occurs. The contribution of optical phonons to thermal conductivity becomes non-negligible and is proposed to play an important role in the glass-like thermal transport behavior (i.e. positive temperature dependence of the thermal conductivity) in the paramagnetic state. These features can be understood in terms of an expression of thermal conductivity that includes both acoustic and optical phonon terms. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410004969 [article] Thermal conductivity of electron-doped CaMnO3 perovskites : Local lattice distortions and optical phonon thermal excitation [texte imprimé] / Yang Wang, Auteur ; Yu Sui, Auteur ; Xianjie Wang, Auteur . - 2011 . - pp. 6306–6316. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6306–6316 Mots-clés : Manganite  perovskite  Thermal  conductivity  Spin-phonon  scattering  MnO6  distortion  Optical  phonon Résumé : The thermal transport properties of a series of electron-doped CaMnO3 perovskites have been investigated. Throughout the temperature range 5–300 K, phonon thermal conductivity is dominant, and both electron and spin wave contributions are negligible. The short phonon mean free paths in this system result in the relatively low thermal conductivities. The strong phonon scatterings stem from the A-site mismatch and bond-length fluctuations induced by local distortions of MnO6 octahedra. The thermal conductivity in the magnetically ordered state is enhanced as a result of the decrease in spin–phonon scattering. The results also indicate that above the magnetic ordering temperature, observable thermal excitation of optical phonons occurs. The contribution of optical phonons to thermal conductivity becomes non-negligible and is proposed to play an important role in the glass-like thermal transport behavior (i.e. positive temperature dependence of the thermal conductivity) in the paramagnetic state. These features can be understood in terms of an expression of thermal conductivity that includes both acoustic and optical phonon terms. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410004969