X. F. Tang

Enhanced thermoelectric performance of graphene nanoribbons

The thermoelectric properties of a series of armchair and zigzag graphene nanoribbons with narrow width are examined using nonequilibrium Green function method and molecular dynamics simulations. It is found that these nanoribbons are rather stable when the edge atoms are passivated by hydrogen and those with armchair edges exhibit much better thermoelectric performance than their zigzag counterparts. Moreover, the corresponding ZT value increases with decreasing ribbon width. By optimizing the doping level, a room temperature ZT of 6.0 can be achieved for the narrowest armchair nanoribbon. The significantly enhanced ZT value makes armchair graphene nanoribbon a promising candidate for thermoelectric applications.

MoS2 nanoribbons as promising thermoelectric materials

The thermoelectric properties of MoS2 armchair nanoribbons with different width are studied by using first-principles calculations and Boltzmann transport theory, where the relaxation time is predicted from deformation potential theory. Due to the dangling bonds at the armchair edge, there is obvious structure reconstruction of the nanoribbons which plays an important role in governing the electronic and transport properties. The investigated armchair nanoribbons are found to be semiconducting with indirect gaps, which exhibit interesting width-dependent oscillation behavior. The smaller gap of nanoribbon with width N = 4 (Here, N represents the number of dimer lines or zigzag chains across the ribbon width) leads to a much larger electrical conductivity at 300 K, which outweighs the relatively larger electronic thermal conductivity when compared with those of N = 5, 6. As a result, the ZT values can be optimized to 3.4 (p-type) and 2.5 (n-type) at room temperature, which significantly exceed the performance of most laboratory results reported in the literature.

Enhanced thermoelectric performance of a quintuple layer of Bi2Te3

The electronic structure of a quintuple layer (QL) of Bi2Te3 is calculated using the first-principles pseudopotential method. It is found that the band gap of an isolated QL is considerably larger than that of bulk Bi2Te3. The electronic transport of the QL is, then, evaluated using the semiclassical Boltzmann theory within the relaxation time approximation. By fitting the energy surface from first-principles calculations, a suitable Morse potential is constructed and used to predicate the lattice thermal conductivity via equilibrium molecular dynamics simulations. By optimizing the carrier concentration of the system, the ZT of Bi2Te3 QL can be enhanced to a relatively high value. Moreover, the ZT value exhibits strong temperature dependence and can reach as high as 2.0 at 800 K. This value can be further increased to 2.2 by the substitution of Bi atoms with Sb atoms, giving nominal formula of (Bi0.25Sb0.75)2Te3. The significantly enhanced ZT value makes QL a very appealing candidate for thermoelectric a...

Effect of γ-Al2O3 Content on the Thermoelectric Performance of ZrNiSn/γ-Al2O3 Composites

ZrNiSn matrix composites containing -Al 2O3 nano particles with a relative density of 98% were prepared by spark plasma sintering technique. Thermal conductivity, Seebeck coefficient, electrical resistivity were measured. It was shown that the addition of small amount of -Al 2O3, which served as the additional phonon-scattering centers, led to a re lative great reduction in thermal conductivity without significantly affecting the power factor. The dimensionless figure of merit ZT of ZrNiSn half-Heusler thermoelectric material was improve d by introducing -Al 2O3 nano particles.

Effects of van der Waals interactions and quasiparticle corrections on the electronic and transport properties of Bi 2 Te 3

We present a theoretical study of the structural, electronic, and transport properties of bulk

Theoretical study of the thermoelectric properties of SiGe nanotubes

{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}

Structural transition of partially Ba-filled thermoelectric CoSb3 investigated by positron annihilation spectroscopy

within density functional theory taking into account the van der Waals interactions (vdW) and the quasiparticle self-energy corrections. It is found that the optB86b-vdW functional can well reproduce the experimental lattice constants and interlayer distances for

Influence of O-Co-O layer thickness on the thermal conductivity of NaxCo2O4 studied by positron annihilation

{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}

Effect of C60 Particle Dispersion on Thermal Conductivity of CoSb3

. Based on the fully optimized structure, the band structure of

Role of vacancy defects on the lattice thermal conductivity in In 2 O 3 thermoelectric nanocrystals: a positron annihilation study

{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}