Ba6−3x Nd8+2x Ti18O54 Tungsten Bronze: A New High-Temperature n-Type Oxide Thermoelectric

Feridoon Azough,Hasan Baig,Guang Han,Robert Freer,Stephen R Yeandel,Jakub D Baran,Nazmi Sellami,Tracy Sweet,Stephen C Parker,Jonathan Siviter,Andrea Montecucco,Emmanuel Guilmeau,Marco Molinari,Demie Kepaptsoglou,Wenguan Li,Gao Min,P Mullen ,Duncan H Gregory ,Douglas J Paul ,Andrew R Knox ,Tapas K Mallick ,Quentin M Ramasse ,Elena Anamaria Man ,Manosh C Paul

doi:10.1007/s11664-015-4275-6

Abstract

Semiconducting Ba6−3xNd8+2xTi18O54 ceramics (with x = 0.00 to 0.85) were synthesized by the mixed oxide route followed by annealing in a reducing atmosphere; their high-temperature thermoelectric properties have been investigated. In conjunction with the experimental observations, atomistic simulations have been performed to investigate the anisotropic behavior of the lattice thermal conductivity. The ceramics show promising n-type thermoelectric properties with relatively high Seebeck coefficient, moderate electrical conductivity, and temperature-stable, low thermal conductivity; For example, the composition with x = 0.27 (i.e., Ba5.19Nd8.54Ti18O54) exhibited a Seebeck coefficient of S1000K = 210 µV/K, electrical conductivity of σ1000K = 60 S/cm, and thermal conductivity of k1000K = 1.45 W/(m K), leading to a ZT value of 0.16 at 1000 K.

Highlights

INTRODUCTIONThermoelectric energy conversion is widely recognized as a promising technology for both electric power generation in terms of waste heat recovery and cooling of various electronic devices.[1]
Thermoelectric energy conversion is widely recognized as a promising technology for both electric power generation in terms of waste heat recovery and cooling of various electronic devices.[1]An efficient thermoelectric material should possess thermal properties similar to those of glass and electrical properties similar to those of perfect single-crystal material, i.e., poor thermal conductivity with good electrical conductivity
The overall performance of polycrystalline ceramics for commercial applications is compromised by large thermal conductivity,[4] k = 8 W/ (m K) to 3 W/(m K), which reduces the thermoelectric figure of merit, ZT = (S2r/k)T, where T is the absolute temperature

Summary

INTRODUCTION

Thermoelectric energy conversion is widely recognized as a promising technology for both electric power generation in terms of waste heat recovery and cooling of various electronic devices.[1]. Been at the center of recent development of n-type high-temperature thermoelectric ceramics and has shown good electrical conductivity, r, and high Seebeck coefficient, S, yielding power factors S2r £ 3.5 mW/K m in single-crystal form.[3] the overall performance of polycrystalline ceramics for commercial applications is compromised by large thermal conductivity,[4] k = 8 W/ (m K) to 3 W/(m K), which reduces the thermoelectric figure of merit, ZT = (S2r/k)T, where T is the absolute temperature. The pentagonal sites are occupied by Ba, and the tetragonal sites are occupied by Nd. At higher levels of Ba, the excess Ba shares the tetragonal sites with Nd. In this study, we investigated the high-temperature thermoelectric properties of tungsten bronze Ba6À3xNd8+2x Ti18O54 ceramics.

EXPERIMENTAL PROCEDURES

RESULTS

CONCLUSIONS