Traditional research on thermoelectric materials focused on improving the figure-of-merit z T to enhance the energy conversion efficiency. With further growth and commercialization of thermoelectric technology beyond niche applications, other factors such as materials availability, toxicity, cost, recyclability, thermal stability, chemical and mechanical properties, and ease of fabrication become important for making viable technologies. Several silicide alloys were identified that have the potential to fulfill these requirements. These materials are of interest due to their abundancy in earth’s crust (e.g., silicon), non-toxicity, and good physical and chemical properties. In this paper, an overview of the silicide thermoelectrics from traditional alloys to advanced material structures is presented. In addition, some of the most effective approaches as well as fundamental physical concepts for designing and developing efficient thermoelectric materials are presented and future perspectives are discussed.

Local thermal magnetization fluctuations in Li-doped MnTe are found to increase its thermopower α strongly at temperatures up to 900 K. Below the Néel temperature (T_N ~ 307 K), MnTe is antiferromagnetic, and magnon drag contributes α_md to the thermopower, which scales as ~T³. Magnon drag persists into the paramagnetic state up to >3 × T_N because of long-lived, short-range antiferromagnet-like fluctuations (paramagnons) shown by neutron spectroscopy to exist in the paramagnetic state. The paramagnon lifetime is longer than the charge carrier–magnon interaction time; its spin-spin spatial correlation length is larger than the free-carrier effective Bohr radius and de Broglie wavelength. Thus, to itinerant carriers, paramagnons look like magnons and give a paramagnon-drag thermopower. This contribution results in an optimally doped material having a thermoelectric figure of merit ZT > 1 at T > ~900 K, the first material with a technologically meaningful thermoelectric energy conversion efficiency from a spin-caloritronic effect.

Harvesting body heat using thermoelectricity provides a promising path to realizing self-powered, wearable electronics that can achieve continuous, long-term, uninterrupted health monitoring. This paper reports a flexible thermoelectric generator (TEG) that provides efficient conversion of body heat to electrical energy. The device relies on a low thermal conductivity aerogel–silicone composite that secures and thermally isolates the individual semiconductor elements that are connected in series using stretchable eutectic gallium-indium (EGaIn) liquid metal interconnects. The composite consists of aerogel particulates mixed into polydimethylsiloxane (PDMS) providing as much as 50% reduction in the thermal conductivity of the silicone elastomer. Worn on the wrist, the flexible TEGs present output power density figures approaching 35 μWcm⁻² at an air velocity of 1.2 ms⁻¹, equivalent to walking speed. The results suggest that these flexible TEGs can serve as the main energy source for low-power wearable electronics.

The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal–semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling. Thermomagnetic effects such as magneto–Peltier and Nernst–Ettingshausen cooling are briefly described and recent advances and future trends in these areas are reviewed. The ongoing progress in solid-state cooling concepts such as spin-calorimetrics, electrocalorics, non-equilibrium/nonlinear Peltier devices, superconducting junctions and two-dimensional materials are also elucidated and practical achievements are reviewed. We explain the thermoreflectance thermal imaging microscopy and the transient Harman method as two unique techniques developed for characterization of thermoelectric microrefrigerators. The future prospects for solid-state cooling are briefly summarized.

Magnesium (Mg) alloys are being investigated as a biodegradable metallic biomaterial because of their mechanical property profile, which is similar to the human bone. However, implants based on Mg alloys are corroded quickly in the body before the bone fracture is fully healed. Therefore, we aimed to reduce the corrosion rate of Mg using a double protective layer. We used a magnesium-aluminum-zinc alloy (AZ91) and treated its surface with micro-arc oxidation (MAO) technique to first form an intermediate layer. Next, a bioceramic nanocomposite composed of diopside, bredigite, and fluoridated hydroxyapatite (FHA) was coated on the surface of MAO treated AZ91 using the electrophoretic deposition (EPD) technique. Our in vivo results showed a significant enhancement in the bioactivity of the nanocomposite coated AZ91 implant compared to the uncoated control implant. Implantation of the uncoated AZ91 caused a significant release of hydrogen bubbles around the implant, which was reduced when the nanocomposite coated implants were used. Using histology, this reduction in the corrosion rate of the coated implants resulted in an improved new bone formation and reduced inflammation in the interface of the implants and the surrounding tissue. Hence, our strategy using a MAO/EPD of a bioceramic nanocomposite coating (i.e., diopside-bredigite-FHA) can significantly reduce the corrosion rate and improve the bioactivity of the biodegradable AZ91 Mg implant.