Abstract The mechanical properties of most hydrogels (ionogels) are considerably affected by covalently cross‐linked networks. However, the interactions between solvent/solvent molecules and solvent/polymer chains are usually ignored. Herein, a series of ultra‐tough ionogels were prepared via a supramolecular solvent, halometallate ionic liquid, in which cations and coordinating anions form a 3D supramolecular network. The linear polymer chains are physically cross‐linked with supramolecular solvents synergistically enhancing the strength (14.3 MPa), toughness (78 MJ m −3 ), and Young's modulus (55 MPa) of ionogels, effectively dispersing the stress concentration under load, and obtaining better fatigue resistance and higher fracture energy (198 kJ m −2 ). Furthermore, the reversible cross‐linking enables green recovery and recycling of ionogels, simply by water. This strategy shows broad applicability based on a variety of supramolecular solvents and coordinatable polymers.
The generation of SBS in discrete Raman gain must be considered along with the problem of limited gain per unit pump power when developing a practical Raman amplifier. In this paper, we focus on discrete Raman amplifier with 15 km dispersion compensating fibers (DCFs). The gain saturation of both forward and backward pumping schemes have been considered and compared. As the pump power increased, the SBS threshold decreased and the reflected power increased dramatically. The 7th SBS stokes have been observed when the pump power is 490mW. The experimental results clearly indicate that the SBS effects produced a saturation of the Raman gain.
Bi0.5Na0.5TiO3 (BNT)-based piezoceramics with the morphotropic phase boundary MPB are confronted with some critical challenges for practical application, such as the low depolarization temperature Td, the poor thermal shock resistance and the high fluctuation of the real-time d33. Herein, by integrating quenching process and successive ferroelectric-relaxor phase transition, the multilayer ceramic composites (0.93Bi0.5Na0.5TiO3-0.07BaTiO3/0.89Bi0.5Na0.5TiO3-0.11BaTiO3/0.85Bi0.5Na0.5TiO3-0.15BaTiO3-4:5:3-Q, abbreviated as BNT-7/11/15BT-4:5:3-Q, the Q and the 4:5:3 refer the quenching process and content ratio, respectively) feature the relatively large d33 (130pC/N) and near the Curie point Td(244℃), which jumps out of the d33-Td trade-off boundary of BNT-based ceramics. Besides, the BNT-7/11/15BT-4:5:3-Q ceramic composite also shows the superior thermal shock resistance and decent temperature stability of real-time d33 over the temperature region from 25℃ to 235℃. Enhanced piezoelectric temperature stability should be attributed to the development of tetragonal P4mm and P4bm phase gradients caused by the successive ferroelectric-relaxor phase transition. In addition, the relatively large d33 stems from the coexistence of rhombohedral R3c phase and tetragonal P4bm and P4mm phases. Therefore, this strategy provides a good design methodology for the practical application of BNT-based materials.
A new self-supporting material contained nanorods α-FeOOH and three-dimensional skeleton graphene foam (3D Graphene Foam, 3DGF) was prepared by hydrothermal method. The growth mechanism and phase change rules of nanorods α-FeOOH@3DGF were studied to obtain the electrochemical lithium storage performance. The results showed that growth mechanism of nanorods α-FeOOH was accompanied by the consumption of nanoparticles β-FeOOH. If the hydrothermal time reached to 12 h, the nanoparticle β-FeOOH phase completely disappeared with only rod-shaped α-FeOOH@3DGF single phase obtained. Rod-shaped α-FeOOH@3DGF was used as anode material of lithium-ion batteries and the reversible specific capacity remained at about 305 mAh·g−1 after charging and discharging 250 times at 500 mA·g−1, with significantly cycling stability compared with that of the monomaterial α-FeOOH.
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