The microstructures of Zr70Cu30 and Zr70Ni30 metallic glasses (MGs) were investigated via the synchrotron radiation techniques combined with the reverse Monte-Carlo simulations. Although Cu and Ni are neighbor elements in the periodic table and their atomic radii are almost the same in length, it is found that atomic- and cluster-scale structural differences occur between these two Zr-based MGs. In particular, the relatively regular clusters caused by the narrow distributions of atomic separations and bond angles are detected in Zr70Cu30. This is the structural origin of the different glass-forming abilities in ZrCu and ZrNi alloys. This work has implications for understanding of the glass-forming mechanism in this class of glassy materials.

Variably spaced semiconductor superlattices (VSSLs) exhibited superior electron mobility and rectification because of electronic level alignment. We investigated the thermoelectric properties of VSSL structures using a self-consistent nonequilibrium Green’s function quantum model to capture the ballistic electron transport and anatomistic nonequilibrium Green’s function model to capture the phonon transport. A figure of merit was calculated as a function of temperature for two VSSL strain silicon–germanium materials and a non-VSSL material. Calculation of the figure of merit (ZT) versus temperature for a VSSL demonstrated a 17 times increase in power factor at the expense of a 4 times increase in thermal conductivity at room temperature compared to a comparable uniform superlattice. Calculation determined a ZT of 0.20 for a VSSL compared to a ZT of 0.04 for non-VSSL material at 400 K. VSSLs proved to be a candidate material to further increased ZT near room temperature for superlattice materials.

The size dependence of the lattice parameter of nanosolids has extensively been studied because lattice strain engineering is important in controlling the physical properties of nanowires (NWs), such as band gap, carrier transport, mechanical strength, etc. We have investigated the size-dependent lattice behavior of microstructure-controlled Sn NWs with radii of 7–35 nm. The NW microstructures were controlled as single-crystal, granular, and bamboo structures in the longitudinal direction. Results showed that the a-axis lattice parameter in the [100]-longitudinal direction of NWs can be controlled within 1% by varying the wire microstructure for the same wire radius because it is strongly dependent on the microstructure and the wire radius. Moreover, as the randomness of the grain orientation in the microstructure-controlled NWs increases, by which the anisotropy of surface stress is effectively reduced, the lattice strain of the NW can be compressive or tensile as a function of the wire radius. The longitudinal lattice parameters of microstructure-controlled Sn NWs can be tailored by reducing the effective anisotropy of surface stresses under a dimension confinement in the nanometer scale.

In- and Yb-doped CoSb3 thin films were prepared by pulsed laser deposition. Process optimization studies revealed that a very narrow process window exists for the growth of single-phase skutterudite films. The electrical conductivity and Seebeck coefficient measured in the temperature range 300–700 K revealed an irreversible change on the first heating cycle in argon ambient, which is attributed to the enhanced surface roughness of the films or trace secondary phases. A power factor of 0.68 W m−1 K−1 was obtained at ∼700 K, which is nearly six times lower than that of bulk samples. This difference is attributed to grain boundary scattering that causes a drop in film conductivity.

A systematic investigation of the intermetallic phase Ru1-yIn3 (0 ≤ y ≤ 0.025) and its substitution derivatives RuIn3-xSnx and RuIn3-xZnx (x = 0.01, 0.025, 0.05, and 0.1) is performed. The samples were prepared from a liquid–solid reaction of components with subsequent spark plasma sintering treatment. Ru1-yIn3 exhibits n- and p-type behavior crossing over from low to high temperatures. Substitution of indium by tin or zinc up to 2.5 at.% leads to an increase of the charge carrier concentration, with negative (Sn) or positive (Zn) Seebeck values, respectively. The electrical resistivity was P changed from semiconductor- to metal-like properties by substitution, whereas the thermal conductivity was reduced down to 50% of that of RuIn3. Higher values of the thermoelectric figure of merit were achieved by chemical substitution (RuIn3-xSnx, RuIn3-xZnx), opening up a possibility for tuning the thermoelectric properties in this class of materials.

Ferromagnetic resonance investigations on Ni nanowires are reported. The angular dependence of the resonance line position is analyzed within a thermodynamic approach that includes shape anisotropy (ellipsoids of revolution), magnetocrystalline anisotropies (cubic and uniaxial), and dipole–dipole interactions. The results are supported by hysteresis loops, obtained on the same sample.

We have synthesized single- and polycrystal Ba8AlxSi46−x clathrates to compare their thermoelectric properties. Single-crystal sample was prepared by Czochralski method in an argon atmosphere. Polycrystal sample was prepared by arc melting and annealed at 850 °C for 100 h in an argon atmosphere. The Seebeck coefficients of single- and polycrystal Ba8Al12Si34 at 500 °C were 44.5 and 53.0 μV/K, respectively. The Seebeck coefficients of both samples were almost the same because the Seebeck coefficients depend on carrier concentration, which is related to aluminum content. The electrical resistivity of the single-crystal sample with 0.49 mΩcm was lower than that of the polycrystal sample with 0.95 mΩcm because of the reduction of electron scattering. Therefore, the power factor of the single-crystal sample with 4.0 × 10−4 V2/K2Ωm was higher than that of the polycrystal sample with 3.0 × 10−4 V2/K2Ωm at 500 °C. It is suggested that single crystallization is efficient for improvement of the thermoelectric property in the Ba8AlxSi46−x clathrate.

Most state-of-the-art thermoelectric (TE) materials contain heavy elements Bi, Pb, Sb, or Te and exhibit maximum figure of merit, ZT∼1–2. On the other hand, oxides were believed to make poor TEs because of the low carrier mobility and high lattice thermal conductivity. That is why the discoveries of good p-type TE properties in layered cobaltites NaxCoO2, Ca4Co3O9, and Bi2Sr2Co2O9, and promising n-type TE properties in CaMnO3- and SrTiO3-based perovskites and doped ZnO, broke new ground in thermoelectrics study. The past two decades have witnessed more than an order of magnitude enhancement in ZT of oxides. In this article, we briefly review the challenges, progress, and outlook of oxide TE materials in their different forms (bulk, epitaxial film, superlattice, and nanocomposites), with a greater focus on the nanostructuring approach and the late development of the oxide-based TE module.

Amorphous ribbons of (Fe1-xCox)88Zr7B4Cu1 (x = 0.2, 0.35, 0.5, and 0.6) alloys were annealed to produce a nanocrystalline phase dispersed in the amorphous matrix. Precision lattice parameter calculation showed that composition of the nanocrystalline phase is Fe73Co27 for all the alloys irrespective of initial alloy composition. This result was well corroborated with the Mössbauer results. Saturation magnetization of annealed ribbons was almost same for all the alloys, however, coercivity increases with Co content.