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Title: Reduced thermal conductivity in niobium-doped calcium-manganate compounds for thermoelectric applications

Reduction of thermal conductivity is essential for obtaining high energy conversion efficiency in thermoelectric materials. We report on significant reduction of thermal conductivity in niobium-doped CaO(CaMnO{sub 3}){sub m} compounds for thermoelectric energy harvesting due to introduction of extra CaO-planes in the CaMnO{sub 3}-base material. We measure the thermal conductivities of the different compounds applying the laser flash analysis at temperatures between 300 and 1000 K, and observe a remarkable reduction in thermal conductivity with increasing CaO-planar density, from a value of 3.7 W·m{sup −1}K{sup −1} for m = ∞ down to 1.5 W·m{sup −1}K{sup −1} for m = 1 at 400 K. This apparent correlation between thermal conductivity and CaO-planar density is elucidated in terms of boundary phonon scattering, providing us with a practical way to manipulate lattice thermal conductivity via microstructural modifications.
Authors:
;  [1]
  1. Department of Materials Science and Engineering, Technion—Israel Institute of Technology, Haifa 32000 (Israel)
Publication Date:
OSTI Identifier:
22391902
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CALCIUM; CALCIUM OXIDES; DOPED MATERIALS; EFFICIENCY; MANGANATES; MICROSTRUCTURE; NIOBIUM; PHONONS; SCATTERING; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; THERMAL CONDUCTIVITY; THERMOELECTRIC MATERIALS