Journal of Materials Science

Wang, Lei; Shen, Xinyi; Gao, Zhixuan; Fu, Jinke; Yao, Suhao; Cheng, Luyao; Lian, Xiaojuan

doi: 10.1007/s10853-022-06954-xpmid: N/A

Neuromorphic systems with large-scale parallel computing capability and low power consumption have become important for the development of artificial intelligence technologies. Memristors have been designed to achieve various computing functions and have been further applied in neuromorphic circuits owing to their high storage density, fast switching speed, ultra-low power consumption, and long endurance cycles. Among the different types of functional materials, 2D materials, which are a novel class of functional materials, have shown great potential in memristive neuromorphic applications because of their atomic-scale thickness, excellent electronic properties, thermal stability, mechanical flexibility, and strength. In addition, by stacking different 2D materials together, van der Waals (vdW) heterostructures retain not only the properties of each 2D material but also exhibit more interesting properties than their respective counterparts; therefore, vdW heterostructures are promising for flexible neuromorphic applications. In this review, we discuss the applications of 2D materials and their vdW heterostructures in memristive neuromorphic circuits from the perspective of material systems, physical mechanisms, advantages, and future challenges.

Zhang, Xiangzhu; Zheng, Lijun; Luo, Xudong; Xie, Zhipeng; Han, Lei; Pei, Jiaao; Liu, Feng

doi: 10.1007/s10853-021-06743-ypmid: N/A

Hierarchically porous diatomite ceramics (HPDCs) doped with ZrSiO4 as the opacifier were successfully prepared by means of foam-gelcasting with diatomite powder as original material. The effects of the opacifier, ZrSiO4, on the microstructure, mechanical properties, and thermal conductivity of the HPDCs were studied. The HPDCs doped with ZrSiO4 showed a typical porous structure with excellent properties such as high porosity (84.5–89.1%) and high compressive strength (0.66–1.99 MPa). The added ZrSiO4 hardly influenced the porosity, bulk density, and compressive strength, but decreased the thermal conductivity, especially at high temperatures. When 5 wt% ZrSiO4 was added to HPDC, its thermal conductivity at 298 and 1073 K decreased to 0.068 and 0.132 W/(m K), respectively. This decrease in the thermal conductivity could be attributed to the outstanding scattering and absorption of the infrared electromagnetic waves by the added opacifier. The results indicated that the addition of ZrSiO4 as an opacifier is a promising approach for enhancing the properties of porous ceramics at high temperatures.

Vigor, James E.; Bernal, Susan A.; Xiao, Xianghui; Provis, John L.

doi: 10.1007/s10853-022-06952-zpmid: N/A

Time-resolved in-situ synchrotron X-ray microtomography reveals new levels of detail about the chemical and physical processes that take place as Portland cement hardens. The conversion of a fluid paste into a hardened product can be monitored on a sub-minute time-scale, and with sample movement/settlement corrections applied to enable individual particles to be tracked as they react, hydrate, and become interconnected into a single strong monolith. The growth of the strength-giving hydrate phases surrounding cement grains, and of the fluid-filled pore network that surrounds them, is able to be directly viewed at the level of individual cement particles through the application of this tracking protocol. When cement is brought into contact with water, a layer which differs in density from the bulk of the cement grains becomes observable on the grain surfaces during the induction period (during which time the heat evolution from the paste is relatively low). As hydration continues, reaction products grow both from particle surfaces into the initially fluid-filled region, and also into the space originally occupied by the cement particles, forming a density gradient within the microstructure. As the reaction accelerates and larger volumes of solid phases precipitate, the newly-formed solid structure percolates via interconnection of agglomerated low-density outer hydrates, which then densify as hydration continues. This eventually leads to solidification of the structure into a hardened porous matrix.Graphical abstract[graphic not available: see fulltext]

Dubov, Oleg; Marcé, Jaume Giralt; Fortuny, Agusti; Fabregat, Azael; Stüber, Frank; Font, Josep

doi: 10.1007/s10853-022-06906-5pmid: N/A

Uniform flexible carbon nitride coatings have been synthesized by means of annealing of films, fabricated from soluble triazine-based polymeric precursors. The coatings exhibit fascinating electrochemical stability and drastically increase the capacitance of coated carbon cloth electrodes. Following the analogue with turbostratic carbons, typically produced by means of polymeric precursors pyrolysis, we demonstrate that annealing of dried nitrogen-rich polymeric films results in coatings, composed by nearly equal atomic quantities of carbon and nitrogen, according to elemental analysis, and exhibiting noticeable mechanical robustness. X-ray difffraction patterns and infrared spectra of the materials allow to characterize them as partially amorphous carbon nitride with presumably heptazinic structure. Annealed films exhibit extrinsic semiconducting behavior with optical bandgaps in the range from 1.71 to 1.99 eV and fairly good conductivity. The outstanding long-term electrochemical stability of annealed films makes them competitive with pyrolytic carbon, while much lower annealing temperatures allow preparation of nanocomposites with various particles. The precursor polymers were obtained by self-condensation of 2-amino-4,6-dichloro-1,3,5-triazine and condensation of cyanuric chloride with 5-aminotetrazole and 3-amino-1,2,4-triazole-5-carboxylic acid, respectively, in N,N-dimethylacetamide. The polymers contain mainly C–N skeletal bonds and can therefore be viewed as “extension” of typical carbon nitride precursors, like melamine or dicyandiamide, to polymeric structure.

Li, Zhihui; Hou, Junhe; Gu, Xin; Gao, Lu; Su, Ge; Li, Fei

doi: 10.1007/s10853-022-06910-9pmid: N/A

Two kinds of core–shell composite particles, i.e., mesoporous-SiO2@Cu (m-SiO2@Cu) and mesoporous-SiO2@TiO2@Cu (m-SiO2@TiO2@Cu) microspheres, were synthesized by coating Cu nanoparticles on the surfaces of m-SiO2 and m-SiO2@TiO2 microspheres. Results show that the m-SiO2 spheres have rougher surfaces and larger specific surface areas than the SiO2 microspheres. Compared with the m-SiO2@Cu microsphere, the m-SiO2@TiO2@Cu microsphere has a hollow structure. Both catalysts showed high catalytic activity to degrade methyl violet and methylene blue dyes. The degradations of two dyes using the m-SiO2@Cu approached 100% after 30 min, while it is slightly less, around 90% for the m-SiO2@TiO2@Cu. The catalytic activity of m-SiO2@Cu lies in Cu nanoparticles, which have large specific surface areas and are insensitive to light. The catalytic activity of m-SiO2@TiO2@Cu not only lies in Cu nanoparticles, but also in TiO2, which is sensitive to light. What’s more, Cu and TiO2 work as metal/semiconductor heterojunction, which enhances the electron–hole separation in m-SiO2@[email protected] abstract[graphic not available: see fulltext]

Wang, Hong; Gao, Guoqiang; Wei, Wenfu; Yang, Zefeng; Yin, Guofeng; Xie, Wenhan; He, Zhijiang; Ni, Ziran; Yang, Yan; Wu, Guangning

doi: 10.1007/s10853-022-06935-0pmid: N/A

The influence of interface temperature on the damage characteristics of C–Cu contacts’ interface plays a critical role in the current-carrying friction process which occurs between the contact pairs. In this paper, a method is proposed to adjust the interface temperature via settling an external heat source. The damage morphology and material transfer of C–Cu contacts are focused on when the range of interface temperature varies from the room temperature (25 °C) to 300 °C. Based on the experimental results, it can be found that high interface temperature can inhibit the surficial erosion of carbon materials, which tends to be obvious, especially along with the increment of current. Moreover, both the delamination wear of carbon surface and the copper-to-carbon transfer behavior decrease with the thermal surge of interface. This beneficial effect of interface temperature results in the reduction in friction coefficient by 14.3%, whereas the negative impacts brought from the high interface temperature are the surface cracking and the rapid recovery of wear rate of carbon materials, under high-current condition.Graphical abstract[graphic not available: see fulltext]

Hernandez, Javier A.; Soni, Bhawna; Iglesias, María C.; Vega Erramuspe, Iris B.; Frazier, Charles E.; Peresin, Maria S.

doi: 10.1007/s10853-022-06938-xpmid: N/A

A major obstacle for polymeric diphenylmethane diisocyanate (pMDI) share market growth in wood-particle and wood-fiber composites is its low adhesive tack property. In this work, we explore the improvement of pMDI tack by partial substitution using natural polymeric fractions derived from soybean hulls available at a relatively low cost. To that end, pectin was isolated from the soybean hull, and the remaining fibrous residue was fibrillated using mechanical treatment to produce both lignin-containing and chemically bleached cellulose nanofibrils (LCNFs and BCNFs, respectively). Pectin-isolated fractions from the soybean hull were chemically characterized. Pectin and nanofibrillated cellulose were used as additives in pMDI dispersions to improve its tack property. To determine the tack properties of the soybean hull-based-pMDI dispersions, rheological analysis was optimized based on an adaptation of the probe-tack test. Results clearly showed increased tack properties in pMDI/pectin/CNFs dispersions with the combination between soybean hull pectin and LCNFs exceeding the sum of their isolated effects compared to pMDI resin alone.

Zhang, Xing; Yang, Fanghong; Sun, Xiaopeng; Li, Wenfei; Yao, Zhanhai

doi: 10.1007/s10853-022-06956-9pmid: N/A

Graphene (GR) has attracted wide attention as a filler for nanocomposites due to unique electrical properties, high specific surface area and mechanical strength. However, it is difficult to disperse uniformly in matrix because of its high surface energy. In this work, the nanocomposites with high DC breakdown strength are successfully prepared by blending newly synthesized voltage stabilizer noncovalent functionalized GR into linear low density polyethylene/linear low density polyethylene-graft-polystyrene (LLDPE/PES). The results show that the electrical insulation properties of nanocomposites are improved significantly due to the introduction of a great number of deep traps by GR. The internal space charge is suppressed obviously and DC breakdown strength of the nanocomposite prepared by introducing 3.0 wt% voltage stabilizer and 0.005 wt% GR reaches 400.1 kV mm−1, which is 41.6% higher than that of pure LLDPE. This study provides a new strategy for the development of polyethylene insulating materials by introducing noncovalent functionalized GR.Graphical abstract[graphic not available: see fulltext]

Xiao, Chu; Peng, Jinfeng; Ding, Yanhuai; Xiao, Fen

doi: 10.1007/s10853-022-06870-0pmid: N/A

Monolayer BSi has received much attention due to its potential applications in the field of energy storage and superconductivity. However, the mechanical properties of monolayer BSi have not been fully elucidated yet. In this paper, the morphology, elastic constants and Young’s moduli of raw and C, N, P, and S doped monolayer BSi have been investigated by the first principle density functional theory (DFT) calculation. The monolayer BSi exhibits an anisotropic mechanical performance. The results indicate that the C, N, P and S doping affect the value of Young’s modulus of BSi, as well as the modulus distribution.

Ghosh, Poulami; Farooq, Umar; Su, Huimin; Pei, Shenghai; Li, Gaomin; He, Wei; Dai, Junfeng; Huang, Li; Huang, Mingyuan

doi: 10.1007/s10853-022-06933-2pmid: N/A

Metal halide perovskites have gained huge research interest within few decades due to their optoelectronic applications. Recently, inorganic metal halide perovskites CsPbX3 (X = Cl, Br, I) has shown the improved stability with promising optical and electrical properties. We report the enhancement of PL intensity and the extension of carrier lifetime from strained CsPbBr3 microwires in air environment. PL intensity is enhanced more than fivefold for all the studied microwires under strain than the original. Maximum enhancement in PL intensity of more than 25-fold has been observed from a wire with lateral width of 630 nm. Based on the experiment and simulation results, we conclude that tensile strain can improve the oxygen adsorption by the defects on the surface of CsPbBr3 microwires, which will suppress the non-radiative transitions and enhance the light emission efficiency. These findings demonstrate that the strain engineering is an effective way to improve the performance of CsPbBr3 microstructures for optoelectronic applications.