Search

The effect of thermal exposure on a mullite fiber was analyzed. This type of mullite fiber, consisting of γ-Al2O3 and amorphous SiO2, was developed for high-temperature applications. Heat treatments at temperatures ranging from 900 °C to 1500 °C for 1h were performed in air. Investigations showed that the tensile strength of the initial fiber was about 1.60 GPa. And the elastic modulus was about 133.51 GPa. The bundles’ strength decreased at 900 °C slightly after thermal treatment, then increased and got a maximum at 1100 °C with 1.65 GPa. At above 1100 °C, the strength degraded sharply due to the mullite phase transformation and the exaggerated grain growth. At 1300 °C, the phase reaction almost finished with a tensile strength of 0.86 GPa. And the strength retention was only 47.50%. When the heat-treated temperature got to 1500 °C, the density of surface defects in the fiber surged, making it too fragile and weak to go through the tensile tests.

Rechargeable sodium-ion batteries (SIBs) are promising candidates for large-scale energy storage owing to their excellent high-power performance. However, Al-based current collectorsat both anodes and cathodes of SIBs, which widely influence the power properties of a variety of electrodes in SIBs, have rarely been investigated. Here, we demonstrate that vertical graphene nanosheets grown on commercial Al foil by the plasma-enhanced chemical vapor deposition (PECVD) method, form a robust connection with the carbon-based conductive network of the electrode, thereby significantly reducing the electrode-current collector interfacial resistance. For sodium vanadium phosphate (NVP) anodes with vertical graphenenanosheetmodified Al foil (G-Al) current collectors, the interfacial resistance between the electrode and current collector is reduced 20-fold compared with that in the case of Al foil. The G-Al current collector reduces the polarization and improves the rate capability compared with that of Al current collectors within both cathodes and anodes of SIBs. At a high rate of 5 C, the capacity retention of NVP cathode with G-Al current collector is 74%, which is much higher than that with Al foil (22%).We believe that the obtained results support the prospect for the widespread use of G-Al current collectors in the further improvement of high-power profiles of SIBs.

To meet the operating requirements of hypersonic flight vehicles in the atmosphere environment, microstructure and mechanical property of 2.5D Al 2O3f/SiO2 composites by thermal shock and fatigue were investigated and compared. After 100000 fatigue tests, cracks hardly formed on the sample surface, and the interfacial bonding or fiber property was barely affected. However, after thermal shock and fatigue tests, the composites underwent typical brittle fracture and had the lowest fracture strength. The mass loss was less than 1%, and the flexural strength reached to 55.6 MPa, with the retention ratio of only 51.1%. The mechanical property degradation of the composites after tests was closely related to microstructure evolution.

In this study, the continuous alumina fibers reinforced alumina matrix (Al2O3/Al2O3) composites were fabricated through sol–gel method at a sintering temperature range of 900–1400 °C, and their mechanical properties were analyzed separately. To explore the effects of sintering temperature on mechanical properties of composites, the high temperature properties of fibers and matrix were studied in a comprehensive manner. Our results suggested that the composites fabricated at different temperatures exhibited two different fracture features (ductile fracture and brittle fracture). Besides, the 1100 °C fabricated composites possessed the highest flexural strength of nearly 150 MPa. Al2O3 fibers displayed excellent thermal stability, and did not undergo phase transition during the preparation process. However, the grain size of fibers increased dramatically at a sintering temperature of 1200 °C, which led to a significant decrease in the mechanical properties. In the meantime, the surface morphology of fibers became very uneven because of grain coarsening. Due to the phase transition from γ-Al2O3 to α-Al2O3 at 1200 °C, the elastic modulus and microhardness of matrix increased significantly. The higher sintering temperature not only intensified the matrix but also strengthened the interface bonding, thus making the composites prone to brittle fracture. In conclusion, the optimal temperature of composites preparation should be lower than 1200 °C.

Oil-soluble compounds containing boron as lubricating additives were restricted by the hydrolysis of borate ester. In order to overcome this problem, cerium borate nanoparticles modified with oleic acid (O-CeB) as a potential substitute for conventional lubricant additive were studied in detail. The microstructures of the prepared nanoparticles were characterized. Tribological properties of cerium borate nanoparticles used as additive in base oil were evaluated, and the worn surface of the steel ball was investigated. The results show that O-CeB possesses better anti-wear ability at relatively higher concentration; in particular, it shows better friction-reducing ability under all these studied concentrations. Under higher load, its anti-wear property and friction-reducing property are better than that of Vanlube 289 in the base oil. Based on these results of interferometric surface profilometer and X-ray photoelectron spectroscopy, it can be deduced that a continuous resistance film containing depositions and the tribochemical reaction products was formed during the sliding process.

The Bi/BiOI heterostructure films grew perpendicular to the FTO substrates were synthesized in-situ through an electrochemical deposition and hydrogen reduction method. The metallic Bi nanoparticles were decorated onto the surface of BiOI nanosheets via an in-situ reduction, induced 6.3 times improvement of photocurrent density, compared to the pristine BiOI at 1.23 V vs. reversible hydrogen electrode(RHE). The enhancement of photoelectrochemical performance was attributed not only to the efficient separation of charge resulted from surface plasmon resonance effect, but also to the fast charge transfer at the interface due to the in-situ reduction of the films. This work provided a simple and facile strategy to in-situ construct heterostructure films, and showed an effective method to improve the photoelectrochemical activity of Bi-based semiconductors.

In this paper, the SiO2 ceramic matrix composites were reinforced by the two-dimensional (2D) braided Al2O3 fibers by sol-gel. To develop the high performance aeroengine with excellent resistance to thermal shock for advanced aerospace application, two different thermal shock temperatures (1100 °C and 1300 °C) and three different thermal shock cycles (10, 20 and 30 cycles) were tested and compared in this paper; besides, the thermal shock resistance of Al2O3/SiO2 composites was investigated in air. Our results suggested that, the flexural strength of the untreated composites was 78.157 MPa, while the residual strength of Al2O3/SiO2 composites under diverse thermal shock cycles and temperatures had accounted for about 95% and 50% of the untreated composites, respectively. Meanwhile, the density and porosity of the composites were gradually increased with the increase in test temperature. Moreover, the changes in fracture morphology and micro-structural evolution of the composites were also observed. Our observations indicated that, the fracture morphology of the composites mainly exhibited ductile fracture at the thermal shock temperature of 1100 °C, whereas brittle fracture at the thermal shock temperature of 1300 °C. Additionally, Al2O3/SiO2 composites belonged to the Oxide/Oxide CMCs, so no new phase was formed after thermal shock tests. Above all, findings of this paper showed that Al2O3/SiO2 composites had displayed outstanding thermal shock resistance.

In the present study, an attempt has been made to synthesis Al6061/SiC/WC hybrid aluminium composites using stir casting method under various mass percentage of reinforcement. The mechanical properties such as compressive strength, tensile strength, hardness and wear resistance have been characterized and investigated. From the micro structural analysis of hybrid composites, it has been observed that reinforcement particles have been uniformly distributed without clustering of particles in matrix alloy. The precipitate of Mg2Si and un-dissolved Al6 (Fe, Mn) in aluminium solid solution has been observed as interfacial reaction. The hardness of hybrid composites has been increased due to incorporation of stiffer and stronger reinforcement in the matrix material. The presence of SiC and WC reinforcement in the matrix alloy can significantly enhance the compressive, tensile strength and wear resistance of aluminum hybrid composite.

Continuous alumina fibers reinforced alumina matrix composites (Al2O3f/Al2O3 composites) were produced by following the sol-gel process effectively, while the ablation behavior was analyzed and compared by means of oxyacetylene torch flame test. The results suggested that Al2O3f/Al2O3 composites showed excellent ablation resistance, but no obvious cracks, pits or holes after ablation. The mass and thickness of the sample were barely changed after ablation. After ablation for 120s at 1800℃, the surface morphology of composite material showed no significant change. With the increase of ablation temperature, there were visible signs of high-temperature and high-pressure gas erosion found on the surface of composites. Then, the molten black material began to appear on the surface, and the delamination phenomenon occurred finally. After ablation at 2200℃, the surface of composites became uneven, manifesting large-scale black molten particles, and the area affected by ablation was increasing obvious.

The general mathematical model of the transcritical CO2 compressor was presented to assess the compressor efficiencies including isentropic efficiency and volumetric efficiency based on the thermodynamic theories and compressor structures. Furthermore, the prototype of the transcritical CO2 system was established and relative measurements were carried out to evaluate the precision of the simulation. Results showed that the volumetric efficiency of the compressor kept decreasing while the isentropic efficiency increased first and then kept almost constant and even declined with the increase in the pressure ratio. Besides, the indicated efficiency and volumetric efficiency declined slightly with the decrease in the suction density corresponding to the increase in suction superheating. As for the effects of compressor structures on the performances, the indicated efficiency increased sharply and then decreased gradually, while the volumetric efficiency kept declining with the increase in the cylinder diameter-to-height ratio, respectively.

In this study, a space heating used transcritical CO2 heat pump system with an R134a subcooling device was proposed and the medium temperature was researched theoretically and experimentally. To validating the existence of the optimal medium temperature, the system performances were studied: the system power dissipation declined, while the heating capacity increased first and then decreased with the augment in medium temperature. To search the reason of the optimal medium temperature, the system parameters of both the refrigerant side and water side were also discussed in detail: the varied trend of the parameters were sophisticated with the change in medium temperature. Additionally, a correlation was established to predict the optimal value of the medium temperature under various conditions with the ambient temperature, water return temperature and water delivery temperature as the independent variables.

SiC coating was prepared on the surface of C/SiC composites by chemical vapor deposition (CVD) method, and then mechanical behavior of CVD-SiC coated C/SiC composites under cold and thermal cycling had been investigated. Specimens were thermally cycled between the temperatures of −100 °C and 100 °C for up to 200 cycles, respectively. The coating was characterized by XRD, SEM and EDS. The results showed that there were no significant changes in the flexural property. CVD-SiC coated C/SiC composites had good mechanical stability in above simulated space environments. While great changes occurred on both elements and structure of the coating, from homogeneous single-phase of SiC into the inner layer of SiC and the outer of C, which caused the change of the bending strength.

SiO 2f /SiO 2 composites were fabricated by sol-gel method, and then the effects of high-temperature (1000–1400 °C) annealing on the microstructure and mechanical property were discussed and compared. The results showed that the composites underwent obvious structural changes after high-temperature annealing. High-temperature annealing markedly affected the mechanical property that decreased with increasing temperature. When the annealing temperature reached 1400 °C, SiO 2f /SiO 2 composites almost failed.

C/SiC composites had been prepared by PIP process. The evolution of microstructure and mechanical properties after high-temperature (>1500 °C) oxidation were discussed and compared. The results showed that PIP-C/SiC composites had been severely damaged after oxidation tests, micro-cracks and holes emerged along with the increasing of the oxidation temperature, which lead to the decreasing of mechanical properties. After high-temperature flexural tests, the thermal mismatch between C fibers and SiC matrix gradually caused the expansion of micro-cracks, which lead to the decreasing of flexural strength. The mechanical performance deteriorated because defects in the matrix increased and some fibers were oxidized. For long-time use at higher temperature (≥1600 °C), it was necessary to develop a more protective coating with higher stability and melting temperature.

Aiming at the problem that giant magnetostrictive actuator has short stroke and is difficult to be popularized. Combining the advantages of large stroke of voice coil motor with high precision of giant magnetostrictive actuator, a coaxial integrated structure of macro-micro composite actuator with large stroke and high precision is proposed. According to the working principle of composite actuator, the coaxial integrated design scheme of composite actuator is verified by electromagnetic field simulation analysis, and in the process of macro motion in 0-20 mm, the distribution of magnetic force line of macro-motion coil, the effect of macro-motion coil on the distribution of micro-motion magnetic field, and the effect of micro-motion coil on macro-thrust are analyzed. The analysis results show that the distribution of magnetic force line is reasonable and the average axial magnetic field intensity of GMM rod is in the range of 495~640A/m in the macro displacement of 0-20mm, and that the static thrust difference of macro moving part is controlled within 4N in the stroke of macro displacement 6-14mm, which indicates that the coaxial integrated design scheme of macro-micro composite actuator is feasible. The research results provide a theoretical basis for the development of large-stroke and high-precision actuators in the field of precision manufacturing.

Hydrophobic antireflective coating is fabricated by physical vapor deposition. The optical, contact angle and laser damage resistance properties are investigated, respectively. The transmittance of the antireflective coating with hydrophobic layer is 99.58% at 1064 nm with normal incidence. The contact angle with water is 115.6[Formula: see text]. The laser damage threshold of the zero probability is 22 J/cm2 at 1064 nm with the 12 ns pulse width. This new hydrophobic antireflective coating can be applied in the areas of astronomical optics, laser medical equipment and solar energy, etc.

A broadband antireflection film was prepared with SiO2 by glancing angle deposition. The refractive index of the SiO2 film was tuned from 1.15 to 1.45 by adjusting the deposition angle. A novel broadband antireflection film was designed with the graded index film. The average reflectivity of antireflection film is less than 0.41% between 400 nm and 1800 nm wavelength range at 0° incident angle.

2.5D SiO2f/SiO2 composites were fabricated by sol–gel process. The mechanical and fracture behavior of SiO2f/SiO2 composites under higher temperature were discussed. The oxidation behavior at 1200 °C and 1500 °C was investigated. The results showed that SiO2f/SiO2 composites had high flexural strength, and the fracture mechanism was a combination of brittle and ductile fracture. After higher temperature oxidation, the fracture mechanism changed to typical brittle/sudden fracture. For long time usage at higher temperature, it was necessary to stabilize SiO2 fibers and SiO2 matrix of SiO2f/SiO2 composites.

ZrB2-SiC coating was prepared on C/SiC composites surface by slurry method, and then the thermal fatigue behavior of ZrB2-SiC coated C/SiC composites was studied. The composition of the coating layers was characterized by XRD, SEM and EDS. With the thickness was 200μm, the coating was ZrB2 and SiC. During thermal cycle between 1773K in air and 373K in boiling water, the weight of the ZrB2-SiC coated composites decreased lightly. The decrease of the flexural strength during the thermal cycle was primarily due to the debonding of the fiber–matrix interfaces and the oxidation of the coated samples. Compared with the uncoated C/SiC composites, the coating played an important role in enhancing the resistance to the thermal shock.

Take water hydraulic slide valve core as the research object. Laser surface texturing (LST) technology was used to improve the valve core carrying capacity and hydrodynamic lubrication characteristics, which can process micro-texture on the surface of the core. And CFD method was taken to calculate flow field of smooth and laser surface texturing core respectively. For studying the influence of valve core micro-texture and valve core overlap lengths on hydrodynamic lubrication characteristic and carrying capacity of the core, core surface pressure distribution, surface pressure and friction force curves were drawn. Results show: The smooth valve core does not produce hydrodynamic lubrication effect, but textured valve core can bring the oil film load capacity, so as to make the effect of mixed friction between valve core and sleeve weaken. And along with the decrease of the core overlap length, the carrying capacity on the surface of the textured valve core does not decrease but increase when the valve core overlap length amount is greater than 2.5mm.The results provide important theoretical reference of studying and applying LST process technology to the valve core friction pair’s lubrication performance.

The evolution of morphology and heterostructure of BiOCl was investigated during an in situ oxidation reaction. Morphology and structure transformation of regular 2D nanoflake, 0D nanosphere or 3D nanoflower was achieved by adjusting the ratio of reagent concentration or reaction temperature, respectively. The enhanced photocatalytic degradation ability and the photocurrent intensity of BiOCl nanomaterials may be attributed to the improved degree of crystallinity and the formation of Bi/BiOCl heterostructure. The photocurrent density of Schottky battery was increased due to enhancing the optical pathway and assisting during charge separation. Crystallinity also contributed to the improvement of the photoelectric conversion efficiency and reduction of the recombination rate of photogenerated electron-hole pairs.

C/SiC composites had been considered as structural material in complex and harsh environments, thermal stability was one of the key issues for C/SiC composites. This study aimed to investigate C/SiC composites in thermal cycling environment. SiC coating on carbon fibers via chemical vapor deposition at time from 0.5 h to 5 h was studied, and then the degradation behavior of coated C/SiC composites had been measured by thermal cycling tests. The results showed that the coating was continuous and uniform, with good surface adhesion. The interface of carbon fibers and SiC coating was partially destroyed during thermal shock tests. The degradation of mechanical properties was closely related to the evolution of the damage in the composites.

Owing to the degradation of mechanical properties of carbon fiber reinforced SiC matrix (C/SiC) composites under oxidation environment, single layer ZrC coating prepared by molten salt method process were employed. A KCl–NaCl–Zr–K 2 ZrF 6 salt mixture was used as reaction medium, Zr reacted carbon fibers to form ZrC coating. The structure and morphology of ZrC coating were characterized by XRD, SEM and EDS analyses. Effects of ZrC coating on mechanical properties and anti-oxidation capability of C/SiC composites fabricated by precursor infiltration and pyrolysis (PIP) process were investigated. The results showed that a uniform, adherent and crack-free ZrC coating was obtained. ZrC-coated C/SiC composites showed brittle fracture behavior and better oxidation resistance. Even after thermal shock tests, the original structure of ZrC-coated C/SiC composites was not destroyed, which showed a higher mechanical properties.

Pristine and erbium-doped ZnS urchinlike hierarchical nanostructures were successfully synthesized via a chemical solution route. Morphologies of ZnS products have been controlled by adjusting sulfur source and the ratio of ethylene glycol to water by volume. The crystal structures, morphologies and chemical composition of samples were analyzed by X-ray powder diffraction, transmission electron microscopy and atomic emission spectrometry. The photoluminescence (PL) properties of samples were analyzed by spectrofluorometer. It was first found that its broad blue emission is originated not from zinc vacancies or just sulfur vacancies but from sulfur vacancies as well as extended sulfur-vacancy states. PL emission spectra of Er-doped ZnS urchinlike architectures indicated that Er doping can increase sulfur vacancies and extended sulfur-vacancy states. Photocatalytic experiments demonstrate that ZnS with 0.1 atomic% of Er3+ performs the best photocatalytic activity. Photogenerated carriers transfer from outer surface to organic molecules and recombination inside ZnS were investigated by adsorbance and PL spectra, respectively. The results suggest that strong adsorptivity of Er-doped ZnS facilitates the transfer of photogenerated carriers from surface of ZnS to dye molecules; however, higher content of Er could in turn assists photogenerated electron–hole recombination inside ZnS.

Porous cobalt aluminum layered double hydroxide (CoAl-LDH) nanoflake arrays on nickel foam were synthesized by a facile hydrothermal synthesis method. The obtained CoAl-LDH film consisted of interconnected nanoflakes with the thicknesses of ~ 20 nm and showed an extended net-like structure. The electrochemical performance of CoAl-LDH nanoflake arrays was tested by cyclic voltammetry and galvanostatic charge/discharge test. The porous CoAl-LDH nanoflake arrays showed good pseudocapacitive performances with high capacitance and good cycle stability. At room temperature, the porous CoAl-LDH nanoflake arrays exhibited a high specific capacitance of 930 F/g at 2 A/g and their specific capacitances were still up to 669 F/g at 16 A/g. A good cycling stability was also observed for the CoAl-LDH nanoflake arrays with a capacitance retention of 88.9% of the highest value after 2000 cycles at 2 A/g.

Carbon fiber-reinforced silicon carbide (C/SiC) composites were well-established light weight materials combining high specific strength and damage tolerance. For high-temperature applications, protective coatings had to provide oxidation and corrosion resistance. The literature data introduced various technologies and materials, which were suitable for the application of coatings. Coating procedures and conditions, materials design limitations related to the reactivity of the components of C/SiC composites, new approaches and coating systems to the selection of protective coatings materials were examined. The focus of future work was on optimization by further multilayer coating systems and the anti-oxidation ability of C/SiC composites at temperatures up to 2073 K or higher in water vapor.

Brake friction composites based on the combinations of banana fiber-barium sulphate were manufactured and characterized for their physical, mechanical and tribological properties. The tribological properties of the friction composites were evaluated following IS 2742 norms on a Chase machine. The experimental outcome reveals that combinations of banana fiber and barium sulphate have a noteworthy impact on the tribological, mechanical and physical properties of the friction composites. Specifically, the friction composites containing 10 wt% banana fiber and 45 wt% barium sulphate content showed highest coefficient of friction, least frictional fluctuations with lowest fade-% compared to the other investigated composites. On the other hand, the wear performance of the composites decreased whereas recovery-% increased with increasing banana fiber and decreasing barium sulphate content. The composite containing 5 wt% banana fiber exhibited the lowest wear whereas, the composite containing 20 wt% banana fiber exhibited the highest recovery-%. Overall, the friction composite with ≤10 wt% banana fiber and ≥45 wt% barium sulphate showed highest coefficient of friction and fade performance with least friction fluctuations.

A laser-diode array side-pumped Nd∶YAP intra-cavity frequency-tripled 447 nm pulse blue laser was reported.After high peak power of polarized 1 341.4 nm fundamental laser was generated by using high frequency laser-diode array side-pump Nd∶YAP crystal,V-type resonator and LN crystal for Q-switched,670.7 nm red laser second harmonic generation(SHG)was obtained with Ⅱcritical phase matching(CPM)KTP ctystal,and 447.1 nm blue laser by sum frequency mixing(SFM)of the 1 341.4 nm and 670.7 nm radiation was obtained withⅠCMP LBO ctystal.The experimental results show that a optimited V-type resonator can increase the efficiency of nonlinear conversion.At the incident pumping power of 92.4 W,the output power of polarized blue laser is 887 mW,the peak power of blue laser is 17.7 kW,and the pulse width is 50 ns,corresponding to an optical-to-optical conversion efficiency of 0.96%.

Liquid refrigerant injection into a suction line is an effective and practical method to reduce the discharge temperature when a scroll compressor operates at high compression ratios. In the present study, correlations among the compressor suction temperature, discharge temperature, heat pump heating capacity, power consumption, coefficient of performance (COP) and the quantity of suction liquid injection are established. The paper presents experimental analysis and a comparison with calculated results of the heat pump water heater (HPWH) performance with suction liquid injection in different conditions. It is found that the suction liquid injection explicitly lowers the discharge temperature of the compressor and the heating capacity of the unit, but the power consumption increases with COP decreasing. In addition, the highest injection ratio must be controlled fewer than 5%. The suction liquid injection has a better effect on the HPWH at the temperature ranging from −15 °C to 20 °C. Within this temperature range, the 5% ratio suction liquid injection decreases the discharge temperature of the compressor by 10 °C, while the heating capacity of the HPWH decreases by less than 5%, power consumption increases by less than 1.5%, and COP decreases by less than 7%.

This paper presents the experimental study of a heat pump water heater (HPWH) using economizer vapor injection system and mixture of R22/R600a. Performances of HPWH using economizer vapor injection system are compared with that at different mixed mass ratios of R22/R600a. Study demonstrates that the heating capacity and energy efficiency ratio (EER) of the unit increased, and the discharge temperature of compressor decreased when using vapor injection and mixing refrigerant of R22/R600a. It is also found that the HPWH unit with economizer vapor injection system has a better performance for the high outlet water temperature under lower temperature conditions at 15% mass ratio of R600a for the mixing refrigerant. In addition, fundamental and practical influence of vapor injection pressure on the HPWH performance has been investigated experimentally. The simplified model is proposed for predicting the optimal vapor injection pressure of compressor using the mixing refrigerant R22/R600a.

Nafion-115 nanowire arrays are synthesized with an extrusion method using AAO membranes as templates. It is indicated that the vacuum treating of AAO templates before surface decoration plays an important role in obtaining high filling rate of the Nafion-115 nanowires in the AAO templates, while the concentration of Nafion-115 DMSO solutions does not affect the filling rate greatly. The optimized parameters to synthesize the Nafion-115 nanowire arrays are studied. The filling rate of the Nafion-115 nanowires in the AAO templates synthesized with the optimized parameters is about 95%. The growth mechanism of Nafion-115 nanowires is discussed to qualitatively explain the experimental results.

Homogenously dispersed Fe and Ni nanoparticles (NPs) are introduced into boron nitride (BN) by pyrolysis of cured borazine containing soluble ferrocene or nickelocene. The crystallization of the borazine-derived BN is significantly improved by using no more than 1 wt% NPs. X-ray diffraction (XRD) suggests that the improved BN obtained at 1200 °C exhibits a higher degree of crystallization close to that obtained at 1600 °C without additives. Transmission electron microscopy (TEM) indicates the formation of Fe or Ni NP-core multilayer BN spheres embedded in amorphous BN, and a corresponding core–shell model is suggested. The Ni NPs exhibit a higher crystallization than Fe NPs, possibly due to the higher solubility of boron in Ni NPs at elevated temperatures. In addition, we discuss the mechanisms by which Fe and Ni NPs improve the crystallization of BN from borazine.

A new scheme of measuring ultra-short optical pulses, based on the photo-elastic effect and cross-phase modulation (XPM) effect in a single-mode fiber, is proposed. In this novel scheme, a variable delay is generated in the former part of the single-mode fiber, and the nonlinear effect is produced in the latter part as a nonlinear medium. The structure including only one single-mode fiber is very simple and low-cost, and needs no complex optical circuit calibration. In addition, XPM effect in the fiber can be realized easily without phase matching. Measured pulses can be retrieved by using principal component generalized projects algorithm based on matrix, and the influences of fiber length and the pulse width on amplitude and phase are studied by numerically simulating the scheme proposed. The results show that the ultra-short optical pulses can be measured when fiber length is equal to 2 km, and the accuracy of measurement is improved by increasing the fiber length. The proposed scheme can realize the measurement of optical ultra-short pulse whose pulse width is above 80 fs.

Ta-doped ZnO transparent conductive films are deposited on glass substrates by rf sputtering at 300 °C. The influence of the post-annealing temperature on the structural, morphologic, electrical, and optical properties of the films is investigated by x-ray diffraction, Hall measurement, and optical transmission spectroscopy. The lowest resistivity of 3.5 × 10−4 Ω.cm is obtained from the film annealed at 400 °C in N2. The average optical transmittance of the films is over 90%. The optical bandgap is found to decrease with the increase of the annealing temperature.

Niobium-doped ZnO (NZO) transparent conductive films are deposited on glass substrates by rf sputtering at 300° C. Effects of sputtering power on the structural, morphologic, electrical, and optical properties of NZO films are investigated by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Hall measurement, and optical transmission spectroscopy. The obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The minimum resistivity of 4.0 × 10−4 Ωcm is obtained from the film grown at the sputtering power of 170 W. The average optical transmittance of the films is over 90%.