The thermodynamics and the growth kinetics of synthesis of the SiC whiskers (SiC w ) from rice hulls are studied in this paper. The results show that the intimate contact of SiO 2 with C in the rice hulls resulted in ...The thermodynamics and the growth kinetics of synthesis of the SiC whiskers (SiC w ) from rice hulls are studied in this paper. The results show that the intimate contact of SiO 2 with C in the rice hulls resulted in the formation of SiC particle (SiC p ) at lower temperature, and the external ash of the hulls (w (SiO 2 )>98%) is the main silicon source for SiCw growth. The metallic composite catalyst increases the selectivity for SiCw growth and the reaction rate. The growth mechanism of the SiCw can be characterized as the VLS (vapour liquid solid) with the presence of the whisker forming catalyst: from SiC nucleation through enlargement and growing with the <1 1 1> crystallographic orientation in a certain diameter, then the SiC w is a complete single crystal of β SiC. The generation reaction of SiO is the rate determing step for synthesis of SiC w .展开更多
Transition metal oxides have attracted intense interest owing to their abundant physical and chemical properties.The controlled preparation of large-area,high-quality two-dimensional crystals is essential for revealin...Transition metal oxides have attracted intense interest owing to their abundant physical and chemical properties.The controlled preparation of large-area,high-quality two-dimensional crystals is essential for revealing their inherent properties and realizing high-performance devices.However,fabricating two-dimensional(2D)transition metal oxides using a general approach still presents substantial challenges.Herein,we successfully achieve highly crystalline nickel oxide(NiO)flakes with a thickness as thin as 3.3 nm through the salt-assisted vapor-liquid-solid(VLS)growth method,which demonstrated exceptional stability under ambient conditions.To explore the great potential of the NiO crystal in this work,an artificial synapse based on the NiO-flake resistive switching(RS)layer is investigated.Short-term and long-term synaptic behaviors are obtained with external stimuli.The artificial synaptic performance provides the foundation of the neuromorphic application,including handwriting number recognition based on artificial neuron network(ANN)and the virtually unsupervised learning capability based on generative adversarial network(GAN).This pioneering work not only paves new paths for the synthesis of 2D oxides in the future but also demonstrates the substantial potential of oxides in the field of neuromorphic computing.展开更多
The methods for synthesizing one-dimensional Si nanowires with controlled diameter are introduced. The mechanism for the growth of Si nanowires and the growth model for different morphologies of Si nanowires are descr...The methods for synthesizing one-dimensional Si nanowires with controlled diameter are introduced. The mechanism for the growth of Si nanowires and the growth model for different morphologies of Si nanowires are described, and the quantum confinement effect of the Si nanowires is presented.展开更多
Nanowires with inhomogeneous heterostructures such as polytypes and periodic twin boundaries are interesting due to their potential use as components for optical, electrical, and thermophysical applications. Additiona...Nanowires with inhomogeneous heterostructures such as polytypes and periodic twin boundaries are interesting due to their potential use as components for optical, electrical, and thermophysical applications. Additionally, the incorporation of metal impurities in semiconductor nanowires could substantially alter their electronic and optical properties. In this highlight article, we review our recent progress and understanding in the deliberate induction of imperfections, in terms of both twin boundaries and additional impurities in germanium nanowires for new/enhanced functionalities. The role of catalysts and catalyst-nanowire interfaces for the growth of engineered nanowires via a three-phase paradigm is explored. Three-phase bottom-up growth is a feasible way to incorporate and engineer imperfections such as crystal defects and impurities in semiconductor nanowires via catalyst and/or interfacial manipulation. ＂Epitaxial defect transfer＂ process and catalyst-nanowire interfacial engineering are employed to induce twin defects parallel and perpendicular to the nanowire growth axis. By inducing and manipulating twin boundaries in the metal catalysts, twin formation and density are controlled in Ge nanowires. The formation of Ge polytypes is also observed in nanowires for the growth of highly dense lateral twin boundaries. Additionally, metal impurity in the form of Sn is injected and engineered via third-party metal catalysts resulting in above-equilibrium incorporation of Sn adatoms in Ge nanowires. Sn impurities are precipitated into Ge bi-layers during Ge nanowire growth, where the impurity Sn atoms become trapped with the deposition of successive layers, thus giving an extraordinary Sn content （〉6 at.%） in Ge nanowires. A larger amount of Sn impingement （〉9 at.%） is further encouraged by utilizing the eutectic solubility of Sn in Ge along with impurity trapping.展开更多
The β-SiC/SiO2 core-shell nanowires with the 'stem-and-node' structure were synthesized in the presence of cerium oxide by the carbothermal reduction of the starch-SiO2 hybrids gel.The samples were characteri...The β-SiC/SiO2 core-shell nanowires with the 'stem-and-node' structure were synthesized in the presence of cerium oxide by the carbothermal reduction of the starch-SiO2 hybrids gel.The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM) and energy-dispersed X-ray(EDX).The results showed that the nanowires consisted of a 20-35 nm diameter crystalline β-SiC core wrapped with a 2-5 n...展开更多
文摘The thermodynamics and the growth kinetics of synthesis of the SiC whiskers (SiC w ) from rice hulls are studied in this paper. The results show that the intimate contact of SiO 2 with C in the rice hulls resulted in the formation of SiC particle (SiC p ) at lower temperature, and the external ash of the hulls (w (SiO 2 )>98%) is the main silicon source for SiCw growth. The metallic composite catalyst increases the selectivity for SiCw growth and the reaction rate. The growth mechanism of the SiCw can be characterized as the VLS (vapour liquid solid) with the presence of the whisker forming catalyst: from SiC nucleation through enlargement and growing with the <1 1 1> crystallographic orientation in a certain diameter, then the SiC w is a complete single crystal of β SiC. The generation reaction of SiO is the rate determing step for synthesis of SiC w .
基金support from the Jiangsu Funding Program for Excellent Postdoctoral Talent,the National Natural Science Foundation of China(No.52372055)the Jiangsu Independent Innovation Fund Project of Agricultural Science and Technology(No.CX(21)3163).
文摘Transition metal oxides have attracted intense interest owing to their abundant physical and chemical properties.The controlled preparation of large-area,high-quality two-dimensional crystals is essential for revealing their inherent properties and realizing high-performance devices.However,fabricating two-dimensional(2D)transition metal oxides using a general approach still presents substantial challenges.Herein,we successfully achieve highly crystalline nickel oxide(NiO)flakes with a thickness as thin as 3.3 nm through the salt-assisted vapor-liquid-solid(VLS)growth method,which demonstrated exceptional stability under ambient conditions.To explore the great potential of the NiO crystal in this work,an artificial synapse based on the NiO-flake resistive switching(RS)layer is investigated.Short-term and long-term synaptic behaviors are obtained with external stimuli.The artificial synaptic performance provides the foundation of the neuromorphic application,including handwriting number recognition based on artificial neuron network(ANN)and the virtually unsupervised learning capability based on generative adversarial network(GAN).This pioneering work not only paves new paths for the synthesis of 2D oxides in the future but also demonstrates the substantial potential of oxides in the field of neuromorphic computing.
基金Project supported by the National Natural Science Foundation of China (Grant No. 19834080)Zhou Peiyuan Special Foundation of Mathematics and Physics
文摘The methods for synthesizing one-dimensional Si nanowires with controlled diameter are introduced. The mechanism for the growth of Si nanowires and the growth model for different morphologies of Si nanowires are described, and the quantum confinement effect of the Si nanowires is presented.
文摘Nanowires with inhomogeneous heterostructures such as polytypes and periodic twin boundaries are interesting due to their potential use as components for optical, electrical, and thermophysical applications. Additionally, the incorporation of metal impurities in semiconductor nanowires could substantially alter their electronic and optical properties. In this highlight article, we review our recent progress and understanding in the deliberate induction of imperfections, in terms of both twin boundaries and additional impurities in germanium nanowires for new/enhanced functionalities. The role of catalysts and catalyst-nanowire interfaces for the growth of engineered nanowires via a three-phase paradigm is explored. Three-phase bottom-up growth is a feasible way to incorporate and engineer imperfections such as crystal defects and impurities in semiconductor nanowires via catalyst and/or interfacial manipulation. ＂Epitaxial defect transfer＂ process and catalyst-nanowire interfacial engineering are employed to induce twin defects parallel and perpendicular to the nanowire growth axis. By inducing and manipulating twin boundaries in the metal catalysts, twin formation and density are controlled in Ge nanowires. The formation of Ge polytypes is also observed in nanowires for the growth of highly dense lateral twin boundaries. Additionally, metal impurity in the form of Sn is injected and engineered via third-party metal catalysts resulting in above-equilibrium incorporation of Sn adatoms in Ge nanowires. Sn impurities are precipitated into Ge bi-layers during Ge nanowire growth, where the impurity Sn atoms become trapped with the deposition of successive layers, thus giving an extraordinary Sn content （〉6 at.%） in Ge nanowires. A larger amount of Sn impingement （〉9 at.%） is further encouraged by utilizing the eutectic solubility of Sn in Ge along with impurity trapping.
基金supported by the National Key Technology R&D Program (2007BEA08B01)the Natural Science Foundation of Fujian Province of China (E0710004)Joint Research Program of Fuzhou University (DH-548)
文摘The β-SiC/SiO2 core-shell nanowires with the 'stem-and-node' structure were synthesized in the presence of cerium oxide by the carbothermal reduction of the starch-SiO2 hybrids gel.The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM) and energy-dispersed X-ray(EDX).The results showed that the nanowires consisted of a 20-35 nm diameter crystalline β-SiC core wrapped with a 2-5 n...
