A giant low-frequency dielectric constant ( epsilon 0 approximately 10(5)) near room temperature was observed in Li,Ti co-doped NiO ceramics. Unlike currently best-known high epsilon 0 ferroelectric-related materials, the doped oxide is a nonperovskite, lead-free, and nonferroelectric material. It is suggested that the giant dielectric constant response of the doped NiO could be enhanced by a grain boundary-layer mechanism as found in boundary-layer capacitors. In addition, there is about a one-hundred-fold drop in the dielectric constant at low temperature. This anomaly is attributed to a thermally excited relaxation process rather than a thermally driven phase transition, as for that yielding ferroelectrics.

Most crystalline inorganic materials, except for metals and some layer materials, exhibit bad flexibility because of strong ionic or covalent bonds, while amorphous materials usually display poor electrical properties due to structural disorders. Here, we report the simultaneous realization of extraordinary room temperature flexibility and thermoelectric performance in Ag2Te1–xSx–based materials through amorphization. The coexistence of amorphous main phase and crystallites results in exceptional flexibility and ultralow lattice thermal conductivity. Furthermore, the flexible Ag2Te0.6S0.4 glass exhibits a degenerate semiconductor behavior with a room temperature Hall mobility of ~750 cm2 V−1 s−1 at a carrier concentration of 8.6 × 1018 cm−3, which is at least an order of magnitude higher than other amorphous materials, leading to a thermoelectric power factor also an order of magnitude higher than the best amorphous thermoelectric materials known. The in-plane prototype uni-leg thermoelectric generator made from this material demonstrates its potential for flexible thermoelectric device.

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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 (TN ~ 307 K), MnTe is antiferromagnetic, and magnon drag contributes αmd to the thermopower, which scales as ~T3. Magnon drag persists into the paramagnetic state up to >3 × TN 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.

The effect of metal-semiconductor Zn-ZnO core-shell structure on dielectric properties of polyvinylidene fluoride (PVDF) composites was investigated. Zn-ZnO fillers were obtained by the heat-treatment of raw Zn particles under air. The enhanced dielectric constant of Zn-ZnO/PVDF composites results from the duplex interfacial polarizations induced by metal-semiconductor interface and semiconductor-insulator interface. The dielectric loss is still low because of the presence of ZnO semiconductor shell between Zn metal core and insulator PVDF matrix. Furthermore, the dielectric performance of as-prepared composites could be further optimized through adjusting the thickness of semiconductor shell.

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ronment without mechanical parts, longlasting, maintenance-free, portable, etc. Therefore, TEGs are especially suitable for applications in self-powered electronic systems. [4][5][6] Most high-performance TE materials are inorganic semiconductors, which show high figure of merit values [7,8] and have irreplaceable applications as power supply systems in space exploration, such as radioisotope TE generators. [9,10] Nevertheless, traditional inorganic TE materials are mechanically rigid and fragile, thus are not compatible with heat sources with complex surfaces, obstructing their applications in distributed power supply systems, especially wearable electronics.Two main strategies have been developed to address these issues. One strategy used intrinsically flexible TE materials, including conducting polymers, [11][12][13] carbon-based materials, [14,15] and highly plastic semiconductors. [16,17] Despite these attractive developments, the intrinsically flexible TE materials still suffered inferior TE properties, and the TEGs based on these films were usually constructed using in-plane configurations that made them difficult to build matched thermal impedance when harvesting heat from human body. Quite recently, ionic TE materials as another candidate for thermal energy conversion, showed a magnitude larger temperature gradient driven voltage based on Soret effect than typical electronic TE materials based on electrons/holes diffusion. [18,19] However, most of the ionic TEGs only functioned Direct energy conversion based on thermoelectric (TE) materials is a longterm and maintenance-free energy harvesting technique, and therefore is very promising for self-powered wearable electronics. Yet, it is challenging to achieve high-performance stretchable, healable, and even recyclable thermoelectric generators (TEGs) without compromising TE conversion performance due to the intrinsic mechanical rigidity and brittleness of the inorganic TE materials. Herein, recyclable, healable, and stretchable TEGs (RHS-TEGs) are reported that are assembled from commercial Bi 2 Te 3 and Sb 2 Te 3 TE legs generating superior power density via the use of liquid metal as interconnects and dynamic covalent thermoset polyimine as encapsulation. The TEGs fabricated using this strategy are endowed with excellent TE performance, mechanical compliance, and healing and recycling capabilities. The normalized output power density and mechanical stretchability can reach up to 1.08 µW cm −2 •K 2 and 50%, respectively. After healing and recycling, the TEGs show output performance comparable to the original devices. The TEGs also exhibit high reliability and stability under cyclic deformation. This study paves the way for sustainable application of TEGs as energy harvesters to power wearable electronics using body heat.

Wearable sensors integrating multiple functionalities have emerged with great potentials in artificial smart systems for perceiving external stimuli such as strain, stress and temperature with high sensitivity simultaneously. Yet, it...