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1.
Appreciable changes in resistance of polycrystalline nanosized CuNb2O6 upon exposure to reducing gases like hydrogen, liquefied petroleum gas (LPG) and ammonia in ambient atmosphere recognize the material as a gas sensor. Nanosized CuNb2O6 synthesized by thermal decomposition of an aqueous precursor solution containing copper nitrate, niobium tartrate and tri-ethanol amine (TEA), followed by calcination at 700 °C for 2 h, has been characterized using X-ray diffraction (XRD) study, transmission electron microscopy (TEM), field-emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX) analysis and Brunauer–Emmett–Teller (BET) surface area measurement. The synthesized CuNb2O6 exhibits monoclinic structure with crystallite size of 25 nm, average particle size of 25–40 nm and specific surface area of 55 m2 g−1.  相似文献   

2.
Ultrasonic transducers based on PZT-5A thick films deposited onto polycrystalline Al2O3 substrates using screen-printing were successfully fabricated. Considering the relatively high sintering temperature of PZT-5A thick films and better impedance matching characteristics with PZT-5A, polished polycrystalline Al2O3 were used as substrates. For electrodes, high quality platinum (Pt) was deposited by a thin film process, because the surface state of electrodes greatly affects the quality of piezoelectric films. Applying Pt/PZT-5A/Pt/Al2O3 structures, dual-element ultrasonic transducers were assembled. The assembled transducers included a wear plate (normally alumina with 40.21 × 106 kg/m2 s of impedance), backing (tungsten carbide-epoxy), electrical matching, an epoxy glue layer, and a housing. The optimum measurement ranges of 5 and 10 MHz ultrasonic transducers were 2.51–300.2 and 2.50–250.1 mm, respectively. From the time and frequency response measurements of the assembled 10 MHz DEUTs, the value of −20 dB level waveform duration and the −6 dB bandwidth was 481.8 ns and 34.4%, respectively. Also, the measurement accuracies of both 5 and 10 MHz DEUTs assembled in this study were below 0.1 and 0.4%, respectively.  相似文献   

3.
Thin amorphous silicon (a-Si) films were crystallized into polycrystalline silicon (poly-Si) by combining solid phase crystallization (SPC) and subsequent excimer laser annealing (ELA). Then thin film transistors (TFTs) were fabricated by using the poly-Si formed in the single and double excimer laser scanned area. The device performance of the TFTs fabricated with the excimer laser energy density of 230 mJ/cm2 is almost equal for the single and double scanned area. This observation indicates that the overlapping laser irradiation with the laser energy density below 230 mJ/cm2 does not change the characteristics of TFTs. Based on this result, we discuss the correlation between performance of active matrix organic light emitting display (AMOLED) panels and excimer laser energy density during ELA for SPC treated and non-treated poly-Si films.  相似文献   

4.
Piezoelectric Pb(Zr,Ti)O3 (PZT) thin films with a composition near the morphotoropic phase boundary were deposited directly on cantilever-shaped stainless steel (SUS) substrates using RF-magnetron sputtering for application of micro-electromechanical systems (MEMS). X-ray diffraction measurements reveal that the PZT thin films have a polycrystalline perovskite structure with a preferential orientation of (1 0 1). Cross-section morphology – observed using a scanning electron microscope – indicates that the PZT films exhibit a dense columnar structure without pores or clacks. The films’ PE hysteresis loops indicate clear ferroelectricity. Based on the deflection characteristics of the cantilever, the effective piezoelectric coefficient e31 of the PZT films is measured to be −1.35 C/m2.  相似文献   

5.
Wei Xu  M.A. Khan 《Displays》2009,30(3):119-122
The electron injection and transport in OLEDs have been improved by using a tris-[8-hydroxyquinoline] gallium (Gaq) layer as step barrier between tris-[8-hydroxyquinoline]aluminum (Alq3) (or 4,7-diphyenyl-1,10-phenanthroline (Bphen)) and 2-t-butyl-9,10-di-(2-naphthyl)anthracene (TBADN). Since the LUMO (lowest unoccupied molecular orbital) of Gaq (2.9 eV) lies in between that of Alq3 (3.1 eV) (or Bphen (3.0 eV)) and TBADN (2.8 eV), step barrier from Alq3 (or BPhen) though Gaq to TBADN can be formed. The experimental results indicate that the JV characteristics of both the electron-only and the complete devices show the increase of the current density in devices with step barrier compared with the devices without step barrier. For electron-only devices, the driving voltage at the current density of 20 mA/cm2 is reduced from 7.9 V to 4.9 V for devices with Alq3, and from 4.2 V to 3.1 V for devices with BPhen, respectively, owing to the introduction of step barrier. For the complete devices, when Gaq step barrier is introduced, at 20 mA/cm2, the driving voltage is reduced from 7 V to 5.8 V for devices with Alq3 and from 6.2 V to 5.1 V for devices with BPhen. It has also been observed that for devices with step barrier layer, the luminance at 200 mA/cm2 is increased from 1992 cd/m2 to 3281 cd/m2 for device with Alq3, and from 1745 cd/m2 to 2876 cd/m2 for devices with BPhen, respectively. The highest luminance reaches 3420 cd/m2 in devices with Alq3 as ETL and 3176 cd/m2 in devices with BPhen as ETL after the introduction of step barrier. The phenomena are explained by using tunnel theory.  相似文献   

6.
Pulsed laser deposited (PLD) Y-doped BaZrO3 thin films (BaZr1-xYxO3-y/2, x = 0.2, y > 0), were investigated as to their viability for reliable humidity microsensors with long-term stability at high operating temperatures (T > 500 °C) as required for in situ point of source emissions control as used in power plant combustion processes. Defect chemistry based models and initial experimental results in recent humidity sensor literature [1] and [2]. indicate that bulk Y-doped BaZrO3 could be suitable for use in highly selective, high temperature compatible humidity sensors. In order to accomplish faster response and leverage low cost batch microfabrication technologies we have developed thin film deposition processes, characterized layer properties, fabricated and tested high temperature humidity micro sensors using these thin films. Previously published results on sputtering Y-doped BaZrO3 thin films have confirmed the principle validity of our approach [3]. However, the difficulty in controlling the stoichiometry of the films and their electrical properties as well as mud flat cracking of the films occurring either at films thicker than 400 nm or at annealing temperature above 800 °C have rendered sputtering a difficult process for the fabrication of reproducible and reliable thin film high temperature humidity microsensors, leading to the evaluation of PLD as alternative deposition method for these films.X-ray Photoelectron Spectroscopy (XPS) data was collected from as deposited samples at the sample surface as well as after 4 min of Ar+ etching. PLD samples were close to the desired stoichiometry. X-ray diffraction (XRD) spectra from all as deposited BaZrO3:Y films show that the material is polycrystalline when deposited at substrate temperatures of 800 °C. AFM results revealed that PLD samples have a particle size between 32 nm and 72 nm and root mean square (RMS) roughness between 0.2 nm and 1.2 nm. The film conductivity increases as a function of temperature (from 200 °C to 650 °C) and upon exposure to a humid atmosphere, supporting our hypothesis of a proton conduction based conduction and sensing mechanism. Humidity measurements are presented for 200–500 nm thick films from 500 °C to 650 °C at vapor pressures of between 0.05 and 0.5 atm, with 0.03–2% error in repeatability and 1.2–15.7% error in hysteresis during cycling for over 2 h. Sensitivities of up to 7.5 atm−1 for 200 nm thick PLD samples at 0.058 atm partial pressure of water were measured.  相似文献   

7.
Helicopter pilots espouse ergonomically unfavourable postures and endure vibration which result in low back pain. The objective of this study was to investigate the effects of a helicopter flight on pilots back and shoulder muscles using surface Electromyography (sEMG) analysis. This study also correlates low back pain symptoms from Rehabilitation Bioengineering Group Pain Scale (RBGPS) questionnaire with muscle fatigue rates obtained. RBGPS was administered on 20 Coast Guard helicopter pilots. sEMG was acquired before and after flight from erector spinae and trapezius muscles in 8 of these 20 pilots. Statistical analysis of time and frequency domain parameters indicated significant fatigue in right trapezius muscle due to flying. Muscle fatigue correlated with average duration of flight (r2 = 0.913), total service as pilot (r2 = 0.825), pain (r2 = 0.463) and total flying hours (r2 = 0.507). However, muscle fatigue weakly correlated with Body Mass Index (BMI) (r2 = 0.000144) and age (r2 = 0.033).  相似文献   

8.
We report the computational modeling of the front side plasmonics effect arising on gold (Au) nanoparticles array in combination with nanotextured silicon surface for thin film silicon solar cells application. The ultimate efficiency of the optimized silicon nanoholes (SiNH) array textured surface using Au plasmonics effect is 38.58 %, which is 24.01 % greater than SiNH array textured surface without Au plasmonics effect. Furthermore, SiNH array textured surface perform better compared to silicon nanopillar (SiNP) array textured surface for all the parameters studied. The maximum possible short circuit current density and power conversion efficiency of the proposed SiNH array textured surface with Au plasmonics effect are 31.57 mA/cm2 and 25.45 % respectively, which compares favorably well to the computed values of 26.17 mA/cm2 and 21.12 %, respectively for the SiNP array textured surface with Au plasmonics effect.  相似文献   

9.
A new Mn(II) complex of MnL2Cl2 (L = azino-di(5,6-azafluorene)-κ2-NN′) was synthesized and utilized as an electrochemical indicator for the determination of hepatitis B virus (HBV) based on its interaction with MnL2Cl2. The electrochemical behavior of interaction of MnL2Cl2 with salmon sperm DNA was investigated on glassy carbon electrode (GCE). In the presence of salmon sperm DNA, the peak current of [MnL2]2+ was decreased and the peak potential was shifted positively without appearance of new peaks. The binding ratio between [MnL2]2+ and salmon sperm DNA was calculated to be 2:1 and the binding constant was 3.72 × 108 mol2 L−2. The extent of hybridization was evaluated on the basis of the difference between signals of [MnL2]2+ with probe DNA before and after hybridization with complementary sequence. Control experiments performed with non-complementary and mismatch sequence demonstrated the good selectivity of the biosensor. With this approach, a sequence of the HBV could be quantified over the range from 1.76 × 10−8 to 1.07 × 10−6 mol L−1, with a linear correlation of r = 0.9904 and a detection limit of 6.80 × 10−9 mol L−1. Additionally, the binding mechanism was preliminarily discussed. The mode of interaction between MnL2Cl2 and DNA was found to be primary intercalation binding.  相似文献   

10.
The Ho3+ and Pr3+ ions co-doped phosphate glasses were prepared by melt quenching procedure with the various composition of (70-x-y)P2O5 + 20SiO2 + 10CaO + xHo2O3 + yPr2O3 (x = 0.4, 0.6, 0.8, 1.0 mol%, y = 0.6, 0.8, 1.0 mol%). The structural investigation (based on X-ray diffraction analysis) confirmed amorphous character of these glass materials. The optical properties were studied. The glass samples have strong absorption at 360 nm, and the excitation light at 360 nm can excite Ho3+ and Pr3+ ions very well, causing them to produce synergistic luminescence. The glass sample 68.8P2O5 + 20SiO2 + 10CaO + 0.4Ho2O3 + 0.8Pr2O3 emits strong white light under 360 nm excitation. The chromaticity coordinate values are x = 0.3378, y = 0.3472 in white light region, and it has a moderate correlated color temperature (CCT) of 5277 K. Decay time data reveals that there is energy transfer from Pr3+ to Ho3+ ions. This glass will be a good material for white light and tunable light emitting.  相似文献   

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