Xin Wang,Jinming Liu,Haiming Chen,Shihao Zhou,Dongsheng Mao
With the vigorous development of the Internet of Things, 5G technology, and artificial intelligence, flexible wearable sensors have received great attention. As a simple and low-cost power supply in wearable sensors, the triboelectric nanogenerator (TENG) has a wide range of applications in the field of flexible electronics. However, most polymers are thermally poor conductors (less than 0.1 W/(m·K)), resulting in insufficient heat dissipation performance and limiting the development of TENG. In this study, a high-performance non-woven fabric TENG with strong thermal conductivity (0.26 W/m·K) was achieved by introducing ZrB2into the polyurethane (PU) matrix. The excellent output performance with an open circuit voltage (Voc) of 347.6 V, a short circuit current (Isc) of 3.61 μA, and an accumulated charge of 142.4 nC endows it with good sensitivity. The electrospun PU/ZrB2composites exhibit excellent sensing performance to detect body movements in situ, such as pressing, clapping, running, and walking. Moreover, the generated power can light up 224 LED bulbs as a demonstration of self-powering ability.
Junnan Zhang,Xuening Rong,Chang Xu,Aming Xie,Shuxin Deng
The developing of electrically conductive materials with extreme thermostability is of great importance in the field of microwaves absorption (MA). However, the dielectric loss of ZrB2 (a typical high-temperature and conducting ceramic) at microwave band still remains to be unexplored. In this paper, we systematically investigate the chemical structures, dielectric properties and MA performance of ZrB2 ceramic at microwave band. High MA performance can be achieved through the regulation of filler loading ratio of ZrB2, where the maximal absorption reaches −43.0 dB at 13.26 GHz at only 1.5 mm. A multi-polarization resonance loss is thought to be the main reason behind the excellent MA performance of ZrB2. This research opens up the exploration of high-temperature ceramic as MA materials.
High-aspect-ratio ZrB 2 rod crystals were synthesized via a molten-salt-mediated boro/carbothermal reduction using ZrOCl 2 · 8H 2 O/B 4 C/C as the raw material and NaCl as the flux material. This synthesis may improve the poor fracture toughness of monolithic ZrB 2 ceramics. X-ray diffraction and scanning electron microscopy confirmed that the heat-treatment temperature of 1550 °C and the addition of 50 wt% NaCl were the most effective in the preparation of ZrB 2 grains with a high aspect ratio. Thermogravimetric and differential scanning calorimetry was used to study the influence of NaCl addition, which increased the liquid-phase content. Finally, the growth of ZrB 2 grains along the c-axis into rod-like morphology at elevated temperatures was investigated by transmission electron microscopy . This work revealed that the addition of NaCl has a positive effect on the reducing of synthesis temperature and increasing of products particle size. The ZrB 2 rod crystals synthesized have diameters and aspect ratios of approximately 1 μm and 30, respectively.
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