title: Development of novel thermoelectric materials by reduction of lattice thermal conductivity.
abstract: Thermal conductivity is one of the key parameters in the figure of merit of thermoelectric materials. Over the past decade, most progress in thermoelectric materials has been made by reducing their thermal conductivity while preserving their electrical properties. The phonon scattering mechanisms involved in these strategies are reviewed here and divided into three groups, including (i) disorder or distortion of unit cells, (ii) resonant scattering by localized rattling atoms and (iii) interface scattering. In addition, we propose construction of a 'natural superlattice' in thermoelectric materials by intercalating anMXlayer into the van der Waals gap of a layeredTX2structure which has a general formula of (MX)1+x(TX2)n(M=Pb, Bi, Sn, Sb or a rare earth element;T=Ti, V, Cr, Nb or Ta;X=S or Se andn=1, 2, 3). We demonstrate that one of the intercalation compounds (SnS)1.2(TiS2)2has better thermoelectric properties compared with pure TiS2in the direction parallel to the layers, as the electron mobility is maintained while the phonon transport is significantly suppressed owing to the reduction in the transverse phonon velocities.
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Japan.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Wan
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Japan.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya, Japan.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.affiliation: CREST, Japan Science and Technology Agency, Kawaguchi, Japan; EcoTopia Science Institute, Nagoya University, Nagoya, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Norimatsu
authors.affiliation: CREST, Japan Science and Technology Agency, Kawaguchi, Japan; EcoTopia Science Institute, Nagoya University, Nagoya, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Kusunoki
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Japan.
authors.forename: Kunihito
authors.initials: K
authors.lastname: Koumoto
keywords: misfit layer compound; natural superlattice; thermal conductivity; thermoelectric