Flexible thermoelectrics provide a different solution for developing portable and sustainable flexible power supplies. The discovery of silver sulfide–based ductile semiconductors has driven a shift ...in the potential for flexible thermoelectrics, but the lack of good p-type ductile thermoelectric materials has restricted the reality of fabricating conventional cross-plane π-shaped flexible devices. We report a series of high-performance p-type ductile thermoelectric materials based on the composition-performance phase diagram in AgCu(Se,S,Te) pseudoternary solid solutions, with high figure-of-merit values (0.45 at 300 kelvin and 0.68 at 340 kelvin) compared with other flexible thermoelectric materials. We further demonstrate thin and flexible π-shaped devices with a maximum normalized power density that reaches 30 μW cm
−2
K
−2
. This output is promising for the use of flexible thermoelectrics in wearable electronics.
A flexible power source
Thermoelectric materials can harvest heat and turn it into power. Heat sources potentially include the heat generated by humans through wearable devices and might enable self-powering systems, but the lack of ductility for most thermoelectrics poses a major problem. Yang
et al
. found a thermoelectric silver/copper–based semiconductor that also is ductile (see the Perspective by Hou and Zhu). This material allows for a thin, flexible device capable of producing power, even when adhered to a wrist. —BG
A flexible thermoelectric was developed from a silver/copper–based semiconductor that can be fashioned into a thin device.
Hetero‐shaped thermoelectric (TE) generators (TEGs) can power the sensors used in safety monitoring systems of undersea oil pipelines, but their development is greatly limited by the lack of ...materials with both good shape‐conformable ability and high TE performance. In this work, a new ductile inorganic TE material, Ag20S7Te3, with high TE performance is reported. At 300–600 K, Ag20S7Te3 crystallizes in a body‐centered cubic structure, in which S and Te atoms randomly occupy the (0, 0, 1) site. Due to the smaller generalized stacking fault energy in the (101¯)010 slip system, Ag20S7Te3 shows better ductility than Ag2S, yielding excellent shape‐conformability. The high carrier mobility and low lattice thermal conductivity observed in Ag20S7Te3 result in a maximum dimensionless figure of merit (zT) of 0.80 at 600 K, which is comparable with the best commercial Bi2Te3‐based alloys. The prototype TEG consisting of 10 Ag20S7Te3 strips displays an open‐circuit voltage of 69.2 mV and a maximum power output of 17.1 µW under the temperature difference of 70 K. This study creates a new route toward hetero‐shaped TEG.
A new ductile inorganic thermoelectric (TE) material, Ag20S7Te3, with high carrier mobility, low lattice thermal conductivity, and a maximum zT of 0.80 at 600 K is reported. The prototype hetero‐shaped TE generator consisting of 10 Ag20S7Te3 strips displays an open‐circuit voltage of 69.2 mV and a maximum power output of 17.1 μW under a temperature difference of 70 K.
Non-classical actions of vitamin D were first suggested over 30 years ago when receptors for the active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), were detected in various tissues and ...cells that are not associated with the regulation of calcium homeostasis, including activated human inflammatory cells. The question that remained was the biological significance of the presence of vitamin D receptors in the different tissues and cells and, with regard to the immune system, whether or not vitamin D plays a role in the normal immune response and in modifying immune mediated diseases. In this article findings indicating that vitamin D is a key factor regulating both innate and adaptive immunity are reviewed with a focus on the molecular mechanisms involved. In addition, the physiological significance of vitamin D action, as suggested by in vivo studies in mouse models is discussed. Together, the findings indicate the importance of 1,25(OH)2D3 as a regulator of key components of the immune system. An understanding of the mechanisms involved will lead to potential therapeutic applications for the treatment of immune mediated diseases.
Manipulating nanowire assembly could help the design of hierarchical structures with unique functionalities. Herein, we first report a facile solution‐based process under ambient conditions for ...co‐assembling two kinds of nanowires which have suitable composition and functionalities, such as Ag and Te nanowires, for the fabrication of flexible transparent electrodes. Then Te nanowires can be etched away easily, leaving Ag nanowire networks with controllable pitch. By manipulating the assembly of Ag and Te nanowires, we can precisely tailor and balance the optical transmittance and the conductivity of the resulting flexible transparent electrodes. The network of Ag nanowires which have tunable pitch forms a flexible transparent conducting electrode with an averaged transmission of up to 97.3 % and sheet resistances as low as 2.7 Ω/sq under optimized conditions. The work provides a new way for tailoring the properties of nanowire‐based devices.
Nano networking: Silver nanowires and Te nanowires are co‐assembled by the Langmuir–Blodgett technique. Etching away the Te nanowires leaves Ag nanowire networks in which the spacing between the Ag wires is controlled by the Te nanowires. By manipulating the spacing between nanowires the optical transparency and electrical conductivity of flexible Ag nanowire electrodes can be precisely tailored.
Wearable touch panels, a typical flexible electronic device, can recognize and feed back the information of finger touch and movement. Excellent wearable touch panels are required to accurately and ...quickly monitor the signals of finger movement as well as the capacity of bearing various types of deformation. High‐performance thermistor materials are one of the key functional components, but to date, a long‐standing bottleneck is that inorganic semiconductors are typically brittle while the electrical properties of organic semiconductors are quite low. Herein, a high‐performance flexible temperature sensor is reported by using plastic Ag2S with ultrahigh temperature coefficient of resistance of −4.7% K−1 and resolution of 0.05 K, and rapid response/recovery time of 0.11/0.11 s. Moreover, the temperature sensor shows excellent durability without performance damage or loss during force stimuli tests. In addition, a fully flexible intelligent touch panel composed of a 16 × 10 Ag2S‐film‐based temperature sensor array, as well as a flexible printed circuit board and a deep‐learning algorithm is designed for perceiving finger touch signals in real‐time, and intelligent feedback of Chinese characters and letters on an app. These results strongly show that high‐performance flexible inorganic semiconductors can be widely used in flexible electronics.
A fully flexible intelligent thermal touch panel based on the intrinsically plastic Ag2S semiconductor can well perceive finger touch signals in real‐time and displays intelligent feed back of Chinese characters and letters on an app.
To date, thermoelectric materials research stays focused on optimizing the material's band edge details and disfavors low mobility. Here, the paradigm is shifted from the band edge to the mobility ...edge, exploring high thermoelectricity near the border of band conduction and hopping. Through coalloying iodine and sulfur, the plain crystal structure is modularized of liquid‐like thermoelectric material Cu2Te with mosaic nanograins and the highly size mismatched S/Te sublattice that chemically quenches the Cu sublattice and drives the electronic states from itinerant to localized. A state‐of‐the‐art figure of merit of 1.4 is obtained at 850 K for Cu2(S0.4I0.1Te0.5); and remarkably, it is achieved near the Mott–Ioffe–Regel limit unlike mainstream thermoelectric materials that are band conductors. Broadly, pairing structural modularization with the high performance near the Mott–Ioffe–Regel limit paves an important new path towards the rational design of high‐performance thermoelectric materials.
By structurally‐functionally modularizing Cu2Te with multiple point defects, mosaic nanograins, and crystal‐amorphicity duality, high thermoelectric performance is obtained near the Mott–Ioffe–Regel limit. This work presents a case of paradigm shift from the band edge to the mobility edge in thermoelectric materials research.
Abstract
In general, inorganic non‐metallic materials exhibit brittleness, and achieving plasticity in wide‐gap semiconductors or dielectrics poses an even greater challenge. Historically, silver ...halides have been suggested to be ductile; however, their deformability under different load modes has not been well demonstrated, and the underlying mechanisms are not fully understood. In this study, the authors demonstrate the excellent plasticity of AgCl and AgBr polycrystals at room temperature under tension, bending, compression, and roller pressing. In particular, the rolling reduction rate of AgCl/AgBr exceeds 97%, corresponding to the plastic extensibility from 3600% to 4200%. The metal‐like plasticity and multiple slip systems are attributed to the ionic features, specifically the Coulombic nature of the Ag‐Cl/Br interactions, and the appreciable polarization of the anions. Such less localized diffuse bonding can be readily switched upon atomic gliding, thus ensuring slip without cleavage. This study contributes to the advancement of the understanding and development of wide‐gap plastically deformable inorganic materials for applications in flexible, shape‐conformable high‐power electronics and dielectrics.
The devices would subject transient thermal shocks (TTS) during operation under extremely harsh conditions of nuclear fusion reactors, which inevitably exert significant impact on the microstructure ...and performance of structural materials. In this work, a reduced activation VCrFeTa0.2W0.2 high-entropy alloy (HEA) was developed by vacuum arc melting. The effects of electron beam induced TTS on its microstructure, microhardness, and corrosion properties were investigated. The results indicate that the weight fraction of each phase changes after TTS, showing a significant decrease in the content of BCC1 phase and an increase in the content of BCC2 and Laves phases. The content of BCC1 phase continues to decrease slightly with increasing the power of TTS. Besides, the microhardness of the alloy increases from ~673 HV to ~714 HV after TTS treatments. In the reduced activation HEA, TTS results in a relatively low corrosion current density of ~0.472 μA/cm2 in 3.5 wt% NaCl solution, around one-third of the current density observed in the as-cast sample. Furthermore, the VCrFeTa0.2W0.2 HEA after TTS exhibits a pitting potential of ~1.165 VSCE, which is much higher than that of the as-cast sample. The refined composite multiscale entropy method is employed to analyze the influence of TTS on current fluctuation behavior during the corrosion process. The reduced activation VCrFeTa0.2W0.2 HEA exhibits excellent properties in harsh environments after TTS, thereby showing advantageous property in the field of nuclear structural materials. Moreover, TTS is an efficient and controllable strategy for the improvement of the HEAs’ microstructures and performances.
•A reduced activation VCrFeTa0.2W0.2 high-entropy alloy is developed.•Transient thermal shock is used to change the microstructure.•Microhardness of the alloy increases from ~ 673 HV to ~ 714 HV.•The corrosion resistance of the alloy is improved by transient thermal shock.•Refined composite multiscale entropy method is used to analyze the corrosion behavior.
Soil physicochemical properties, soil microbial biomass and bacterial community structures in a rice-wheat cropping system subjected to different fertilizer regimes were investigated in two seasons ...(June and October). All fertilizer regimes increased the soil microbial biomass carbon and nitrogen. Both fertilizer regime and time had a significant effect on soil physicochemical properties and bacterial community structure. The combined application of inorganic fertilizer and manure organic-inorganic fertilizer significantly enhanced the bacterial diversity in both seasons. The bacterial communities across all samples were dominated by Proteobacteria, Acidobacteria and Chloroflexi at the phylum level. Permutational multivariate analysis confirmed that both fertilizer treatment and season were significant factors in the variation of the composition of the bacterial community. Hierarchical cluster analysis based on Bray-Curtis distances further revealed that bacterial communities were separated primarily by season. The effect of fertilizer treatment is significant (P = 0.005) and accounts for 7.43% of the total variation in bacterial community. Soil nutrients (e.g., available K, total N, total P and organic matter) rather than pH showed significant correlation with the majority of abundant taxa. In conclusion, both fertilizer treatment and seasonal changes affect soil properties, microbial biomass and bacterial community structure. The application of NPK plus manure organic-inorganic fertilizer may be a sound fertilizer practice for sustainable food production.
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