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A multiple pre-doping system with a looser structure displays small fractional volume expansion.

Si is a promising high-capacity anode material; however, its practical implementation is hindered by its huge volume expansion, low initial Coulombic efficiency (ICE), poor cycling life, and high c...

A promoting effect of hydroxyls on silicon surface to the decomposition of electrolyte is discovered by comparing the performance of silicon-hydroxyl (Si-OH) and silicon-alkyl (Si-C3H7) electrodes....

Real-time and accurate fault detection and isolation is very important to ensure the reliability and precision of integrated inertial navigation and global navigation satellite systems. In this paper, the detection performance of a residual chi-square method is analysed, and on this basis an improved method of fault detection is proposed. The local test based on a standardised residual is introduced to detect and identify faulty measurements directly. Differing from the traditional method, two appropriate thresholds are selected to calculate the weight factor of each measurement, and the gain matrix is adjusted adaptively to reduce the influence of the undetected faulty measurement. The sliding window test, which uses past measurements, is also added to further improve the fault detection performance for small faults when the local test based on current measurements cannot judge whether a fault has occurred or not. Several simulations are conducted to evaluate the proposed method. The results show that the improved method has better fault detection performance than the traditional detection method, especially for small faults, and can improve the reliability and precision of the navigation system effectively.

Silicon/carbon (Si/C) composites have rightfully earned the attention as anode candidates for high-energy-density lithium-ion batteries (LIBs) owing to their advantageous capacity and superior cycling stability, yet their practical application remains a significant challenge. In this study, we report the large-scale synthesis of an intriguing micro/nanostructured pore-rich Si/C microsphere consisting of Si nanoparticles tightly immobilized onto a micron-sized cross-linked C matrix that is coated by a thin C layer (denoted P-Si/C@C) using a low-cost spray-drying approach and a chemical vapor deposition process with inorganic salts as pore-forming agents. The as-obtained P-Si/C@C composite has high porosity that provides sufficient inner voids to alleviate the huge volume expansion of Si. The outer smooth and robust C shells strengthen the stability of the entire structure and the solid-electrolyte interphase. Si nanoparticles embedded in a microsized cross-linked C matrix show excellent electrical conductivity and superior structural stability. By virtue of structural advantages, the as-fabricated P-Si/C@C anode displays a high initial Coulombic efficiency of 89.8%, a high reversible capacity of 1269.6 mAh g

Si/Cu3Si@C composites encapsulated in CNTs network (SCC-CNTs) were synthesized via the combination of ball-milling and CVD methods. SCC-CNTs consist of conductive Cu3Si, amorphous carbon layer, cross-linked CNTs, and the etched pores, which can play the synergistic effects on the improvement of electronic conductivity and Li+ diffusion. The volume expansion of Si anode is also suppressed during the electrochemical process. The SCC-CNTs composites demonstrate a remarkably improved electrochemical performance compared with pure Si, which can deliver a discharge capacity of 2 171 mAh·g−1 at 0.4 A·g−1 with ICE of 85.2%, and retain 1 197 mAh· g−1 after 150 cycles. This work provides a facile approach to massively produce the high-performance Si-based anode materials for next-generation LIBs.

Silicon is regarded as the next-generation alternative anode material of lithium–ion battery due to the highest theoretical specific capacity of 4200 mAh g−1. Nevertheless, the drastic volume expansion/shrink (~ 300%) during the lithiation/delithiation process and the poor electrical conductivity obstruct its commercial application. Herein, we report a novel design of litchi-structural Si@C nanoparticles (L-S Si@C) as long cycle life anode material for lithium–ion battery. The L-S Si@C with nanosized (~ 50 nm) SiC dispersed in the inner surface and ~ 6 wt% carbon layer covering the outer surface delivers a specific capacity of 1145 mAh g−1 in the initial cycle and maintains a specific capacity of 570 mAh g−1 after 300th cycling times, which can be attributed to the specially structurally stable L-S Si@C nanoparticles.

A realistic stochastic model is the prerequisite in global navigation satellite system (GNSS) positioning applications. Considering that Beidou satellite navigation system (BDS) consists of geostationary earth orbit (GEO), inclined geosynchronous satellite orbit (IGSO) and medium earth orbit (MEO) satellites operating in different orbits with different heights, only one model being used in stochastic modeling is probably inadequate, which is the usual case for Global Positioning System (GPS). In this contribution, a new strategy of stochastic modeling for hybrid constellation BDS precise relative positioning is proposed, namely multiple elevation-dependent models (MEDM). In MEDM, parameters of three elevation-dependent models for GEO, IGSO, MEO satellites are estimated independently. After that, variances of phase and code observations for different orbits satellites can be estimated, then the stochastic model specific for BDS can be constructed in real time. The experimental results reveal that, when MEDM is compared with the sole elevation-dependent model and the carrier-to-noise power density ratios (C/N0)-dependent model, the maximum improvements in ambiguity resolution success rates (SR) in 5, 6, 7, 8 available satellites cases are about 0.2%, 13%, 3%, 1% for B1 frequency, and 1%, 6%, 2.5%, 0.2% for B2 frequency, respectively. The overall improvements in baseline solutions by using MEDM are in millimeter or submillimeter level. Hence, MEDM is more suitable for hybrid constellation of BDS in precise relative positioning applications.

Attitude Dilution of Precision (ADOP) is an important indicator that reflects the relationship between attitude errors and noise in carrier phase observations for Global Navigation Satellite System (GNSS) attitude determination. Several definitions of the ADOP have been put forward by some scholars so far. However, there is no widely accepted standard ADOP definition currently. Therefore, the most exact ADOP definition need to be selected to compare the attitude determination performance of BDS and GPS stand-alone and integrated system. In this paper, three representative ADOP definitions are studied. Theoretical analysis and data simulation show that the ADOP definition proposed by Gomez is the best among these three definitions. After that, the ADOP for BDS and GPS integrated attitude determination is defined based on the ADOP-Gomez definition. BDS and GPS stand-alone and integrated ADOP are calculated in a three-antenna static attitude determination experiment. The experimental results demonstrate that the ADOP for GPS stand-alone system is on the whole lower than BDS stand-alone system, which means the geometry strength of GPS for attitude determination is stronger than BDS. Even so, the ADOP for BDS is nearly close to GPS in the condition that the visible satellite numbers of BDS and GPS are almost the same. It is also concluded that the ADOP for BDS and GPS integrated system significantly decreases compared with their stand-alone system.

Rapid and reliable ambiguity resolution is the key to high-precision global navigation satellite system-based applications. To improve the efficiency and reliability of ambiguity resolution, one effective method is equipping the reference station with an antenna array of known geometry instead of a single antenna. In this contribution, the benefits of reference antenna array-aided real-time kinematic (RTK) positioning are investigated. The mathematical relations between the number of reference antennas and the float baseline and ambiguity solutions are explored, and the closed-form formula of ambiguity dilution of precision (ADOP) is further presented. It is demonstrated that the maximum decrease in ADOP or the improvement in precision of float solutions is approximately 29.29% with the increase in the number of reference antennas. Then, we analyze the impact of errors (noises or biases) on the float baseline and ambiguity solutions. Finally, the performance of the array-aided RTK is evaluated with raw BDS and GPS observations in terms of the ambiguity resolution success rate, false alarm, wrong detection alarm, and the time-to-first-fix (TTFF). It is demonstrated that the array-aided RTK can deliver improved ambiguity success rates with respect to the standard one-reference-antenna RTK, especially when only single-frequency, single-system observations from fewer satellites are available. Moreover, the array-aided RTK can provide much more robust ambiguity resolution in the presence of biases. And the performance of suppressing false alarm and wrong detection alarm is improved as well. Additionally, the TTFF with single-frequency observations is also significantly shortened. One order of magnitude improvements in TTFF are achieved for most of the cases from the standard one-reference-antenna solutions to the three-reference-antenna solutions. The results confirm that the array-aided RTK ensures more reliable and efficient ambiguity resolution.

A priori attitude information can improve the success rate and reliability of Global Navigation Satellite System (GNSS) multi-antennae attitude determination. However, a priori attitude information is nonlinear, and integrating a priori information into the objective function rigorously will increase the complexity of an ambiguity domain search, such as the Multivariate Constrained-Least-squares Ambiguity Decorrelation Adjustment (MC-LAMBDA) method. In this paper, a new method based on attitude domain search is presented to make use of the a priori attitude angle information with high efficiency. First, the a priori information of pitch and roll is integrated into the search process to derive the analytic search step for attitude angle, and the integer candidates are determined by traversal search in the three-dimensional attitude domain. Then, the objective function is parameterised with Euler angles, and a non-iterative approximate method is utilised to simplify the iterative computation in calculating objective function values. Experimental results reveal that compared to the MC-LAMBDA method, our new method has the same success rate and reliability, but higher efficiency in making use of a priori attitude information.

Usually, the global navigation satellite system (GNSS)-based attitude determination and the GNSS-based relative positioning are treated as separate problems. In this contribution, the two problems are resolved as a combined solution of a joint model with multivariate constraints, in which the known geometry of the antenna array on the rover platform is used as constraints, thereby improving the parameter estimation in not only the attitude determination but also the relative positioning. The objective function of the joint model is decomposed and then reduced so that only the terms concerning the constraints are retained, thus transforming the objective function into the exact form of that of the GNSS-based multivariate constrained attitude determination model. Then the multivariate constrained least-squares ambiguity decorrelation adjustment method together with the efficient shrinkage or expansion with bounds strategies, which are shown to work well in the attitude determination, can be extended to the joint model. In experimental validation, the joint model is tested with both simulated and real GPS/BDS datasets in terms of ambiguity resolution success rate and the precision of solutions. The results confirm that the joint model ensures the highest ambiguity resolution success rate among the existing unaided GNSS-based relative positioning methods, and the improvement is more obvious when the observation model is weaker, for example, when the number of available satellites is fewer or when the precision of observations is poorer, thus showing an overall best performance in both reliability and precision aspects.

The initialization is a critical step in the BeiDou Navigation Satellite System and microelectromechanical inertial measurement unit (MIMU)-integrated attitude determination. One of the primary tasks in the initializing process is integer ambiguity resolution. The rapidity and reliability of integer ambiguity resolution play a particularly important role in kinematic attitude determination. However, the common ambiguity function method (AFM) is time consuming and unreliable due to searching over the entire yaw and pitch range. In view of the fact that MIMU can provide initial pitch by self-alignment with the three-axis accelerometers, we present a pitch-constrained AFM (PCAFM) for single-epoch and single-frequency integer ambiguity resolution. Although only pitch information is available, both pitch and yaw search spaces can be constrained in PCAFM. The pitch search space is constrained by the initial pitch from MIMU, and then the yaw search candidates are reduced by the constrained pitch range with the mathematical relationship between yaw and pitch in the DD carrier-phase observation equation. Experimental results demonstrate that the yaw and pitch search candidates of PCAFM are greatly decreased by 67.55% and 97.51%, respectively. Meanwhile, the success rate of integer ambiguity resolution is improved compared with the AFM.

The observability and observable degree of attitude errors in tightly coupled global navigation satellite system/inertial navigation system attitude determination system are studied in this paper. The mathematical relationship between the observable degree and the attitude dilution of precision (ATDOP) is determined by the singular value decomposition of the observability Gramian. The influence of the ATDOP on the observable degree is analyzed. The observability analysis of the attitude errors under different numbers of visible satellites is performed via a rank test of the observability Gramian. The results of a field test demonstrate that, a higher observable degree of attitude error will be obtained for the pitch, roll and yaw at a given time under a lower ATDOP. When the number of visible satellites is equivalent, a lower ATDOP leads to a higher observable degree of error for any one of the three attitudes at different times. Moreover, the results show that the three attitude errors are all externally observable under the condition of at least three visible satellites with three antennas.

Real-time kinematic (RTK) ambiguity resolution can be improved by engaging multiple reference antennas. The baseline information between the antennas can be taken as true values and used as a hard-constraint; or it can be regarded as weighted, a priori measurements, and used as a soft-constraint. In this contribution, a comparison between the two constraints is made to explicate their difference in RTK ambiguity resolution for some specific applications, in which the coordinates of the reference antennas cannot be accurately calibrated in advance. The functional and stochastic models of the hard and soft-constrained RTK positioning are given. The float ambiguity precision of the unconstrained, the hard and the soft-constrained cases is compared. The closed-formulae of the ambiguity dilution of precision (ADOP) for the unconstrained and the hard-constrained models are derived, and they are proven to be the upper and lower bound of the soft-constrained ADOP, respectively. A simulated and a real data show that, with the hard or soft-constraints, the single-frequency ambiguity resolution success rate, as well as the performance in time-to-first-fix (TTFF), is improved significantly. When there is a bias smaller than 6 cm in the a priori baseline vectors between the reference antennas, the two constraints have a comparable performance in ambiguity success rate. Also, a sharp increase in the hard-constrained TTFF is observed at the same time. When the bias gets larger, the hard-constrained ambiguity success rates are decreased drastically. In contrast, the soft-constraint maintains a relatively good performance, showing a much greater tolerance for bias.

Silicon (Si) is considered as the most promising candidate for anode materials in the next-generation lithium-ion batteries (LIBs). Regulating the morphology and structure of Si plays a vital role in alleviating the volume expansion and improving electronic conductivity. Herein, an ingenious core-shell structure (denoted as CoMOF-D@Si@C) is synthesized by depositing Si uniformly on the pyrolytic metal-organic frameworks (MOFs) via chemical vapor deposition (CVD) method and then encapsulated with a carbon shell. The CoMOF-D@Si@C exhibits excellent rate capability and cycle performance, which delivers a high-rate capability of ~957 mAh g−1 at 10 A g−1 and a reversible capacity of 1493 mAh g−1 after 400 cycles. In particular, the capacity is maintained at 648 mAh g−1 after 1200 cycles at a high current density of 4 A g−1 with a rapid increase of the Coulombic efficiency (CE) to 99.8% after only 5 cycles and the average CE (99.7%) in the whole cycling at 4 A g−1. Profiting from the outer carbon shell, uniform Si deposition and inner porous pyrolytic MOF structure, this architecture can maintain structural stability and provide constructive conductivity during cycling processes. The superior electrochemical performance of the CoMOF-D@Si@C composite makes it a promising anode material for LIBs.

Silicon is regarded as the next generation anode material for lithium-ion batteries because of its high specific capacity, low intercalation potential and abundant reserves. However, huge volume changes during the lithiation and delithiation processes and low electrical conductivity obstruct the practical applications of silicon anodes. In this study, a treble-shelled porous silicon (TS-P-Si) structure was synthesized via a three-step approach. The TS-P-Si anode delivered a capacity of 858.94 mA h g−1 and a capacity retention of 87.8% (753.99 mA h g−1) after being subjected to 400 cycles at a current density of 400 mA g−1. The good cycling performance was due to the unique structure of the inner silicon oxide layer, middle silver nano-particle layer and outer carbon layer, leading to a good conductivity and a decreased volume change of this silicon-based anode.

The abrupt fault contained in GNSS measurement will reduce the accuracy of SINS/GNSS loosely-coupled integrated navigation. To solve this problem, the performance of residual chi-square test method is analyzed, on this basis, an improved fault detection and tolerance method based on robust adaptive adjustment is proposed. The local test is implemented to detect and identify the faulty observation. Aiming at the problem that the small size of fault is hard to detect, the gain matrix is adjusted adaptively by using the robust adaptive factor to improve the fault tolerance ability for the missed detection. This in turn improves the detection performance of local test method for the small size of fault. The simulation results show that compared with conventional methods, this method has better performance for the abrupt fault especially small size of fault, and can improve the accuracy and reliability of integrated system effectively.

For Global Navigation Satellite System (GNSS) single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA) method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.

Aiming at the problems that huge amount of computation in ambiguity resolution with multiple epochs and high-order matrix inversion occurred in the GPS kinematic relative positioning, a modified algorithm for fast integer ambiguity resolution is proposed. Firstly, Singular Value Decomposition (SVD) is applied to construct the left null space matrix in order to eliminate the baselines components, which is able to separate ambiguity parameters from the position parameters efficiently. Kalman filter is applied only to estimate the ambiguity parameters so that the real-time ambiguity float solution is obtained. Then, sorting and multi-time (inverse) paired Cholesky decomposition are adopted for decorrelation of ambiguity. After diagonal elements preprocessing and diagonal elements sorting according to the results of Cholesky decomposition, the efficiency of decomposition and decorrelation is improved. Lastly, the integer search algorithm implemented in LAMBDA method is used for searching the integer ambiguity. To verify the validity and efficacy of the proposed algorithm, static and kinematic tests are carried out. Experimental results show that this algorithm has good performance of decorrelation and precision of float solution, with computation speed also increased effectively. The final positioning accuracy result with static baseline error less than 1 cm and kinematic error less than 2 cm, which indicates that it can be used for fast kinematic positioning of high precision carrier. Com o objetivo de solucionar os problemas envolvendo enorme quantidade de cálculos na resolução de ambiguidade com multiplas épocas e inversão de matriz de alta ordem como ocorre no posicionamento relativo cinemático GPS, um algoritmo modificado para resolução rápida da ambiguidade é proposto. Em primeiro lugar, Decomposição de Valor Singluar (SVD) é aplicada para construir a matriz de espaço nulo de modo a eliminar os parâmetros das componentes da linha de base, o qual é capaz de separar os parâmetros de ambiguidade dos parâmetros de posição de forma eficiente. O Filtro de Kalman é aplicado somente para estimar os parâmetros de ambiguidade de tal forma que a solução float em tempo real é obtida. Então, é adotada a decomposição de Cholesky ordenada e multi-temporal (inversa) pareado (multi-time paired Cholesky decorrelation) para a descorrelação das ambiguidades. Após o pré-processamento dos elementos diagonais e da ordenação destes elementos de acordo com os resultados da decomposição de Cholesky, a eficiência da decomposição e decorrelação é melhorada. Posteriormente, o algoritmo de busca inteiro implementado no método LAMBDA, é usado para estimar a ambiguidade inteira. Para verificar a validade e eficácia do algoritmo proposto, experimentos no modo estático e cinemático foram realizados. Os resultados experimentais mostram que este algoritmo tem o bom desempenho de descorrelação e precisão da solução float, com aumento eficaz na velocidade de cálculo. A acurácia do posicionamento em linha de base estática apresentou menor que 1 cm e no caso cinemático foi inferior a 2 cm, o que indica que o método pode ser usado para o posicionamento cinemático rápido com alta precisão da fase.

Si with high theoretical capacity has long suffered from its large volume variation and low electrical transport linked to poor cycling stability and rate performance. Here, a facile approach is reported to mass produce nanostructured Si@carbon with a tunable size of silicon nanoparticles. We performed carbon coating of Si nanoparticles by polyacrylonitrile (PAN) emulsifying and then carbonization. The hollow Si@C nanostructure was obtained via direct etching of Si nanoparticles with HF solution which is more advanced and has better controllability. When evaluated as an anode material for lithium-ion batteries, the C–Si nanocomposites exhibit excellent reversibility and cycling performance. A high capacity of 700 mA h g−1 can be retained after 100 cycles at current densities of 250 mA g−1. The rate capability of the C–Si microfibers is also improved. The special structure is believed to offer better structural stability upon prolonged cycling and to improve the conductivity of the material. This simple strategy could also be applied to prepare other carbon coatings of hollow energy materials.

To mitigate the problem of larger search zone, low initializing efficiency and limited attitude accuracy existing in result zone searching algorithm bounded by ambiguity, an improved algorithm based on dual-frequency combination is proposed. The long wavelength of wide-lane combination is first applied to compress the searching zone. The integer ambiguity of wide lane can be fixed with the assistance of two-dimension result zone searching model. Then the initial integer ambiguity of narrow lane can be obtained based on the related constrained relationship between dual-frequency carriers. The final integer ambiguity of narrow lane can be obtained by the OVT window sliding test method. Taking the final integer ambiguity into narrow-lane carrier observation equation, we can get accurate baseline coordinates and angle information. Comparable experiments demonstrate that the initializing time is reduced by 13 s (from 53 s to 40 s). The baseline accuracy and attitude accuracy are enhanced by 15 and 18%, respectively. These indicate that the proposed method can be widely applied in static orientation and attitude measuring.

In this work, an effective approach to engineer Si and crystal SiO2 nanoparticles with carbon for high performance electrochemical energy storage was presented. We designed an intercalated carbon mixed SiO2&Si nanoparticles/carbon multilayer structure on the Cu current collector for an electrochemically stable and high energy density Si based electrode and carried out by alternately depositing C and SiO2&Si by plasma decomposition of CH4 and SiH4. This design allows for increasing mass loading per geometric area and improving the energy density. The structure and chemical composition of the composites were characterized by SEM, TEM, XRD, XPS, etc. The electrode with 12 layers exhibited an excellent cycling retention and a reversible areal capacity of ∼ 0.46 mAh/cm2 at a current rate of 52 μA/cm2, which is much higher than most of previously reported values of various other materials. The versatile approach for fabricate the intercalated SiO2&Si/carbon films electrodes presented in this work can be extended to a variety of energy conversion and storage applications.

Various shapes of Cu@SiO2 nanowires were fabricated on a Cu substrate via simple thermal evaporation of SiO within a high-frequency induction furnace. The morphology and structure of the Cu@SiO2 nanowires were characterized by using SEM, TEM, EDS and EDX elemental mapping. The morphology and density of the nanowires are controllable by adjusting the substrate temperature. The Cu cores are chemically stable due to the protection of the SiO2 shell. The surface-enhanced Raman scattering (SERS) experiment on the shell-isolated nanowires showed excellent detecting performance compared with the bare Cu substrate. The cathodoluminescence (CL) investigation reveals that red, green and blue light emission was observed in the Silica sheath simultaneously. The as-synthesized samples have potential application in long acting and ultrasensitive SERS substrates and white light sources.

For the integration of global navigation satellite system (GNSS) and inertial navigation system (INS), real-time and accurate fault detection is essential to enhance the reliability and precision of the system. Among the existing methods, the residual chi-square detection is still widely used due to its good real-time performance and sensibility of fault detection. However, further investigation on the performance of fault detection for different observational conditions and fault models is still required. In this paper, the principle of chi-square detection based on the predicted residual and least-squares residual is analyzed and the equivalence between them is deduced. Then, choosing the chi-square detection based on the predicted residual as the research object, the influence of satellite configuration and fault duration time on the performance of fault detection is analyzed in theory. The influence of satellite configuration is analyzed from the number and geometry of visible satellites. Several numerical simulations are conducted to verify the theoretical analysis. The results show that, for a single-epoch fault, the location of faulty measurement and the geometry have little effect on the performance of fault detection, while the number of visible satellites has greater influence on the fault detection performance than the geometry. For a continuous fault, the fault detection performance will decrease with the increase of fault duration time when the value of the fault is near the minimal detectable bias (MDB), and faults occurring on different satellite&rsquo, s measurement will result in different detection results.

Dual-antenna attitude determination technology based on global navigation satellite system can measure the attitude of transporters continuously and accurately. The correct resolution of integer ambiguity is the basis. Integer ambiguity resolution methods with single epoch data for attitude determination are immune to influence of cycle clip and provide attitude determination immediately, but for most methods, the differences are large between the float solution and the correct integer ambiguity, the search space are large, and the validation of integer ambiguity is difficult. For these problems, baseline constrained iteration least square algorithm used the known baseline length which is proposed to improve the float solution; threshold changes step-by-step to reduce search space; the validation of integer ambiguity is accomplished by comparing the calculated baseline vectors using BDS and GPS data after the baseline length validation. The results of actual testing show that the success rate is more than 98 %, the integer ambiguity resolution method can be effectively used for attitude determination with single epoch data.

If the flexible transparent and free-standing paper-like materials that would be expected to meet emerging technological demands, such as components of transparent electrical batteries, flexible solar cells, bendable electronics, paper displays, wearable computers, and so on, could be achieved in silicon, it is no doubt that the traditional semiconductor materials would be rejuvenated. Bulk silicon cannot provide a solution because it usually exhibits brittleness at below their melting point temperature due to high Peierls stress. Fortunately, when the silicon's size goes down to nanoscale, it possesses the ultralarge straining ability, which results in the possibility to design flexible transparent and self-standing silicon nanowires paper (FTS-SiNWsP). However, realization of the FTS-SiNWsP is still a challenging task due largely to the subtlety in the preparation of a unique interlocking alignment with free-catalyst controllable growth. Herein, we present a simple synthetic strategy by gas flow directed assembly of a unique interlocking alignment of the Si nanowires (SiNWs) to produce, for the first time, the FTS-SiNWsP, which consisted of interconnected SiNWs with the diameter of ~10 nm via simply free-catalyst thermal evaporation in a vertical high-frequency induction furnace. This approach opens up the possibility for creating various flexible transparent functional devices based on the FTS-SiNWsP.

2H-SiC–α-Al2O3 epitaxial heterostructures in a 1-D nanosystem were achieved via a simple CVD (chemical vapor deposition) process. Detailed structural characterizations and elemental analyses were carried out using methods such as elemental mapping, EELS (electron energy loss spectroscopy), XPS (X-ray photoelectron spectroscopy) and Raman spectroscopy, which identified the amounts of Al atoms that occupied the Si sites in the SiC lattice and that a small quantity of oxygen atoms were found on the SiC side. The carbon atoms dissolve in the Al2O3 crystal, substituting the oxygen elements, and there is only a small amount of Si in the Al2O3 part. These results supply a comprehensive understanding about the interface and information about the atoms that diffuse between 2H-SiC and α-Al2O3. We hope that this work contributes to the design of SiC–Al2O3 based epitaxial heterostructures.

Large scale and uniform SiO2 nanowires have been successfully fabricated in a high-frequency induction furnace via a Ge-catalyzed vapor liquid solid (VLS) mechanism. The nanowires were characterized by scanning electron microscopy, transmission electron microscopy, XRD and Raman spectroscopy. The results show that the as-synthesized SiO2 nanowires have an amorphous structure with diameters of 20–50 nm, and lengths up to tens of micrometres. The room-temperature photoluminescence measurement of the products show that they have a blue emission band at 420 nm, reveal that the high yield, and ultralong SiO2 nanowires might have potential applications in the future optoelectronic devices. Furthermore, the growth mechanism of the SiO2 nanowires is discussed.