Nano particles lanthanum modified lead titanate (PLT) thin films are grown on Pt/Ti/SiO 2/Si substrate by liquid source misted chemical deposition (LSMCD). PLT films are deposited for 4-8 times, and then annealed at v...Nano particles lanthanum modified lead titanate (PLT) thin films are grown on Pt/Ti/SiO 2/Si substrate by liquid source misted chemical deposition (LSMCD). PLT films are deposited for 4-8 times, and then annealed at various temperature. XRD and SEM show that the prepared films have good crystallization behavior and perovskite structure. The crystallite is about 60 nm. The deposition speed is 3 nm/min. This deposition method can exactly control stoichiometry ratios, doping concentration ratio and thickness of PLT thin films. The best annealing process is to bake at 300 ℃ for 10 min and anneal at 600 ℃ for 1 h.展开更多
Initially studied and developed by students in universities, the very small pico satellites （with a mass lower than 1 kg） are more and more considered for science applications. In particular, there are plans to use ...Initially studied and developed by students in universities, the very small pico satellites （with a mass lower than 1 kg） are more and more considered for science applications. In particular, there are plans to use them in constellations of small spacecraft for remote sensing of various regions of the magnetosphere. They require a payload with specific size, weight and power consumption. In order to respond to this demand, new instruments have to be developed. Those instruments should exhibit at least the same performances as those used in larger satellites while fulfilling the specific requirements imposed by the satellites size. For this reason, the authors currently develop a xylophone bar magnetometer （XBM） based on micro-electromechanical systems （MEMS） with integrated detector electronics. The principle of this magnetometer is based on a classical resonating xylophone bar. A sinnsoidal current oscillating at the fundamental bending resonant frequency of the bar is applied through the device, and when an external magnetic field is present, the resulting Lorentz force yields the bar to vibrate at its fundamental mode with a displacement directly proportional to the amplitude in one direction of the ambient magnetic field. When designing a MEMS XBM, the detection method is a crucial aspect. The measurement method largely influences the geometry of the magnetometer as well as the manufacturing technology. Due to the constraints in terms of size, weight and power consumption, the two most promising measurement methods are capacitive and piezoelectric ones. Several designs including these measurement techniques are presented and simulated under realistic conditions. First, designs including lateral electrodes for capacitive measurement are tackled based on Silicon-On-Insulator （SOI） process. For the piezoelectric detection, a new configuration based on Lead Zirconate Titanate （PZT）/Pt structure is introduced and leads to much better sensitivity than the traditional Pt/PZT/Pt sandwich structure. Finally, the principle of electronic circuits enabling high sensitivity and low power consumption are proposed.展开更多
The lead-free SrZrO3-modified Bi0.5Na0.5TiO3(BNT-SZ100 x, with x=0-0.15) ceramics were fabricated by a conventional solid-state reaction method. The effects of SZ addition on BNT ceramics were investigated through X-r...The lead-free SrZrO3-modified Bi0.5Na0.5TiO3(BNT-SZ100 x, with x=0-0.15) ceramics were fabricated by a conventional solid-state reaction method. The effects of SZ addition on BNT ceramics were investigated through X-ray diffraction(XRD), scanning electron microscopy(SEM), ferroelectric and electric field-induced strain characterizations. XRD analysis revealed a pure perovskite phase without any traces of secondary phases. Ferroelectric and bipolar field induced-strain curves indicated a disruption of ferroelectric order upon SZ addition into BNT ceramics. A maximum value of remnant polarization(32 μC/cm2) and piezoelectric constant(102 pC/N) was observed at 5%(mole fraction) of SZ. Maximum value of the electric field-induced strain(Smax=0.24%) corresponding to normalized strain(Smax/Emax= d*33= 340 pm/V) was obtained at BNT-SZ9.展开更多
A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excit...A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.展开更多
he perovskite-type PbTiO3 has been synthesized by the method of mixed oxides. The appropriate conditions for preparing have been reported. The obtained PbTiO3 powder is pure and fine. The decolorization of dyes in a ...he perovskite-type PbTiO3 has been synthesized by the method of mixed oxides. The appropriate conditions for preparing have been reported. The obtained PbTiO3 powder is pure and fine. The decolorization of dyes in a PbTiO3 suspension system is over 90%. In this paper the photocatalytic ability of PbTiO3 and the factors of influence are discussed.展开更多
New polymer film materials with good properties are reported. The difference between positive and negative coronas is also given. The films have good transmittance, excellent thermal and long-term stability, low diele...New polymer film materials with good properties are reported. The difference between positive and negative coronas is also given. The films have good transmittance, excellent thermal and long-term stability, low dielectric constant, and high glass transition temperature.展开更多
Aromatic bromides are important chemicals in nature and chemical industries.However,their tra‐ditional synthesis routes suffer from low atomic economy and pollutant formation.Herein,we show that organic-inorganic hyb...Aromatic bromides are important chemicals in nature and chemical industries.However,their tra‐ditional synthesis routes suffer from low atomic economy and pollutant formation.Herein,we show that organic-inorganic hybrid perovskite methylammonium lead bromide(MAPbBr_(3))nanocrystals stabilized in aqueous HBr solution can achieve simultaneous aromatic bromination and hydrogen evolution using HBr as the bromine source under visible light irradiation.By hybridizing MAPbBr_(3) with Pt/Ta_(2)O_(5) and poly(3,4‐ethylenedioxythiophene)polystyrene sulfonate as electron‐and hole‐transporting motifs,aromatic bromides were achieved from aromatic compounds with high yield(up to 99%)and selectivity(up to 99%)with the addition of N,N‐dimethylformamide or its analogs.The mechanistic studies revealed that the bromination proceeds via an electrophilic attack pathway and that HOBr may be the key intermediate in the bromination reaction.展开更多
The study of nano properties of PbSe （lead selenide） thin films deposited on TiO2 semi conductor film prepared by sol gel method was a new work destined to perfect the nano materials used in photovoltaic energy. The...The study of nano properties of PbSe （lead selenide） thin films deposited on TiO2 semi conductor film prepared by sol gel method was a new work destined to perfect the nano materials used in photovoltaic energy. The growth of the first group of the fihns （Set 1： P（9）） ＆ P（14）） was based on the decomposition of lead citrate and sodium selenosulphite in the presence of sodium citrate and sodium hydroxide with ammonia and triethalamine （TEA） acting as the complexing agents and P.H stabilizers; while in the second group （Set 2： Pc15~）, the reaction bath was made up of solutions of lead nitrate Pb（NO3）2, PVA （polyvinyl alcohol）, H20 （distilled water）, NH3 （ammonia）, sodium selenosulphite （Na2SeSO3） and Triethalamine [N（CH2CH2OH）], which was used as the complexing agent. The deposited materials were identified by X-ray diffraction. In addition, nano optical and morphological investigations were also performed. The sample P9 has the lowest absorbance of about 0.3 nm in the ultra-violet region. It was found that there was a reduction in the optical absorbance as the wavelength increases. The optical band gap shows a range of 1.26-2.00 eV with sample PcIs~ having the lowest direct band gap.展开更多
Effect of titanium dioxide （TiO2） and carbon additives in the respective positive and negative material properties and the influence on the performance of the battery were investigated. The electrode samples were ch...Effect of titanium dioxide （TiO2） and carbon additives in the respective positive and negative material properties and the influence on the performance of the battery were investigated. The electrode samples were characterized by BET （Brunauer Emmett Teller）, XRD （X-ray diffractometer）, SEM （scanning electron microscopy） and EIS （electrochemical impedance spectroscopy） to understand the surface area, phase, structure, morphology and electrical conductivity of the respective electrode material. The surface area was obtained as 2.312 m2＂g＂l and 0.892 m2＂g＂1, respectively for 12% of activated carbon in the expander of negative and 0.70% of TiO2 （Titanium dioxide） in the PAM （positive active material）. The structural analysis reveals an increase in the tetrabasic lead sulfate and also evidenced by well grown crystals in the PAM with the TiO2, respectively obtained by XRD and SEM techniques. The impedance spectra analysis shows an increase of electrical conductivity of negative active mass with temperature. The battery results showing two fold enhancements in the charge acceptance were attributed to the high surface area activated carbon in the NAM （negative active material）. The materials properties of electrodes and their influence on the battery performance were discussed.展开更多
ABX3-type organic-inorganic hybrid halide perovskite materials have been recognized as promising candidates for optoelectronic applications. However, poor stability of organic-inorganic hybrid perovskite hinders their...ABX3-type organic-inorganic hybrid halide perovskite materials have been recognized as promising candidates for optoelectronic applications. However, poor stability of organic-inorganic hybrid perovskite hinders their forward long-term utilization and hence an effective strategy is needed to replace the organic part with an inorganic cation. Herein, all inorganic CsPbI3 nanowires with a di- ameter of 50-100 nm are synthesized on fluorine-doped tin oxide glass via a simple solution-dipping process, which are further transformed into CsPbBr3 nanowires through a so- lution-phase halide exchange method. A phase change from non-perovskite to perovskite structure is observed during the ion substitution process of I- by Br-, which is elaborated by X-ray diffraction, absorption and photoluminescence spectra. We for the first time apply the as-formed CsPbI3 and CsPbBr3 nanowires into perovskite solar cells, yielding power conversion efficiency of 0.11% and 1.21%, respectively. The inorganic CsPbBr3 nanowire solar cell shows impressive sta- bility which still remains 99% of the initial power conversion efficiency even after 5500 h aging.展开更多
The quality of the perovskite light absorption layer plays a dynamic role in the photovoltaic properties of solar cells.The existing methods to prepare methylammonium lead iodide(MAPbI3)films render substantial struct...The quality of the perovskite light absorption layer plays a dynamic role in the photovoltaic properties of solar cells.The existing methods to prepare methylammonium lead iodide(MAPbI3)films render substantial structural defect density,particularly at the grain boundaries and film surface,constituting a challenge that hinders the further optoelectronic enhancement of perovskite solar cells.Herein,a unique approach was introduced:using a simple ethylammonium chloride(EACl)additive in perovskite precursor mixture to produce high-quality MAPbI3 thin films.The results indicated that EACl could encourage perovskite crystal growth without experiencing the intermediate phase formation and would evaporate from the perovskite after annealing.Additionally,a gradient perovskite structure was achieved using this technique,which impressively enhanced the performance of the perovskite films.A high power conversion efficiency(PCE)of 20.03%was achieved under the optimal amount of EACl,and the resultant efficient device could retain over 89%of the original PCE after aging for 1000 h at room temperature.This novel technique leads to a facile fabrication of highquality and less-defect perovskite thin films for competent and stable devices.展开更多
Organolead trihalide perovskite materials have been attracting increasing attention due to their promising role in solid solar cells. Several advantages make them potential candidates for optoelectronics:(1) solution-...Organolead trihalide perovskite materials have been attracting increasing attention due to their promising role in solid solar cells. Several advantages make them potential candidates for optoelectronics:(1) solution- or/and vapor-processed preparation at low temperature;(2) tunable optical bandgap, wide absorption spectrum but narrow photoluminescence peaks;(3) long car-rier life time, large diffusion length and high charge mobility;(4) various nanostructures via tuning capping agents and sol-vents. In this review, we summarize recent attempts toward efficient LEDs based on organolead trihalide perovskite materials. The strategies of materials science, device design and interface engineering are highlighted. Recent development and future perspectives are summarized for practical perovskite light technologies.展开更多
文摘Nano particles lanthanum modified lead titanate (PLT) thin films are grown on Pt/Ti/SiO 2/Si substrate by liquid source misted chemical deposition (LSMCD). PLT films are deposited for 4-8 times, and then annealed at various temperature. XRD and SEM show that the prepared films have good crystallization behavior and perovskite structure. The crystallite is about 60 nm. The deposition speed is 3 nm/min. This deposition method can exactly control stoichiometry ratios, doping concentration ratio and thickness of PLT thin films. The best annealing process is to bake at 300 ℃ for 10 min and anneal at 600 ℃ for 1 h.
文摘Initially studied and developed by students in universities, the very small pico satellites （with a mass lower than 1 kg） are more and more considered for science applications. In particular, there are plans to use them in constellations of small spacecraft for remote sensing of various regions of the magnetosphere. They require a payload with specific size, weight and power consumption. In order to respond to this demand, new instruments have to be developed. Those instruments should exhibit at least the same performances as those used in larger satellites while fulfilling the specific requirements imposed by the satellites size. For this reason, the authors currently develop a xylophone bar magnetometer （XBM） based on micro-electromechanical systems （MEMS） with integrated detector electronics. The principle of this magnetometer is based on a classical resonating xylophone bar. A sinnsoidal current oscillating at the fundamental bending resonant frequency of the bar is applied through the device, and when an external magnetic field is present, the resulting Lorentz force yields the bar to vibrate at its fundamental mode with a displacement directly proportional to the amplitude in one direction of the ambient magnetic field. When designing a MEMS XBM, the detection method is a crucial aspect. The measurement method largely influences the geometry of the magnetometer as well as the manufacturing technology. Due to the constraints in terms of size, weight and power consumption, the two most promising measurement methods are capacitive and piezoelectric ones. Several designs including these measurement techniques are presented and simulated under realistic conditions. First, designs including lateral electrodes for capacitive measurement are tackled based on Silicon-On-Insulator （SOI） process. For the piezoelectric detection, a new configuration based on Lead Zirconate Titanate （PZT）/Pt structure is introduced and leads to much better sensitivity than the traditional Pt/PZT/Pt sandwich structure. Finally, the principle of electronic circuits enabling high sensitivity and low power consumption are proposed.
基金supported by the Basic Research program through the National Research Foundation of Korea (NRF) funded by Ministry, Science and Technology (MEST) (2011-0030058)
文摘The lead-free SrZrO3-modified Bi0.5Na0.5TiO3(BNT-SZ100 x, with x=0-0.15) ceramics were fabricated by a conventional solid-state reaction method. The effects of SZ addition on BNT ceramics were investigated through X-ray diffraction(XRD), scanning electron microscopy(SEM), ferroelectric and electric field-induced strain characterizations. XRD analysis revealed a pure perovskite phase without any traces of secondary phases. Ferroelectric and bipolar field induced-strain curves indicated a disruption of ferroelectric order upon SZ addition into BNT ceramics. A maximum value of remnant polarization(32 μC/cm2) and piezoelectric constant(102 pC/N) was observed at 5%(mole fraction) of SZ. Maximum value of the electric field-induced strain(Smax=0.24%) corresponding to normalized strain(Smax/Emax= d*33= 340 pm/V) was obtained at BNT-SZ9.
文摘A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.
文摘he perovskite-type PbTiO3 has been synthesized by the method of mixed oxides. The appropriate conditions for preparing have been reported. The obtained PbTiO3 powder is pure and fine. The decolorization of dyes in a PbTiO3 suspension system is over 90%. In this paper the photocatalytic ability of PbTiO3 and the factors of influence are discussed.
基金The National Natural Science Foundation of China!(No. 69688005 and No. 69890230)
文摘New polymer film materials with good properties are reported. The difference between positive and negative coronas is also given. The films have good transmittance, excellent thermal and long-term stability, low dielectric constant, and high glass transition temperature.
文摘Aromatic bromides are important chemicals in nature and chemical industries.However,their tra‐ditional synthesis routes suffer from low atomic economy and pollutant formation.Herein,we show that organic-inorganic hybrid perovskite methylammonium lead bromide(MAPbBr_(3))nanocrystals stabilized in aqueous HBr solution can achieve simultaneous aromatic bromination and hydrogen evolution using HBr as the bromine source under visible light irradiation.By hybridizing MAPbBr_(3) with Pt/Ta_(2)O_(5) and poly(3,4‐ethylenedioxythiophene)polystyrene sulfonate as electron‐and hole‐transporting motifs,aromatic bromides were achieved from aromatic compounds with high yield(up to 99%)and selectivity(up to 99%)with the addition of N,N‐dimethylformamide or its analogs.The mechanistic studies revealed that the bromination proceeds via an electrophilic attack pathway and that HOBr may be the key intermediate in the bromination reaction.
文摘The study of nano properties of PbSe （lead selenide） thin films deposited on TiO2 semi conductor film prepared by sol gel method was a new work destined to perfect the nano materials used in photovoltaic energy. The growth of the first group of the fihns （Set 1： P（9）） ＆ P（14）） was based on the decomposition of lead citrate and sodium selenosulphite in the presence of sodium citrate and sodium hydroxide with ammonia and triethalamine （TEA） acting as the complexing agents and P.H stabilizers; while in the second group （Set 2： Pc15~）, the reaction bath was made up of solutions of lead nitrate Pb（NO3）2, PVA （polyvinyl alcohol）, H20 （distilled water）, NH3 （ammonia）, sodium selenosulphite （Na2SeSO3） and Triethalamine [N（CH2CH2OH）], which was used as the complexing agent. The deposited materials were identified by X-ray diffraction. In addition, nano optical and morphological investigations were also performed. The sample P9 has the lowest absorbance of about 0.3 nm in the ultra-violet region. It was found that there was a reduction in the optical absorbance as the wavelength increases. The optical band gap shows a range of 1.26-2.00 eV with sample PcIs~ having the lowest direct band gap.
文摘Effect of titanium dioxide （TiO2） and carbon additives in the respective positive and negative material properties and the influence on the performance of the battery were investigated. The electrode samples were characterized by BET （Brunauer Emmett Teller）, XRD （X-ray diffractometer）, SEM （scanning electron microscopy） and EIS （electrochemical impedance spectroscopy） to understand the surface area, phase, structure, morphology and electrical conductivity of the respective electrode material. The surface area was obtained as 2.312 m2＂g＂l and 0.892 m2＂g＂1, respectively for 12% of activated carbon in the expander of negative and 0.70% of TiO2 （Titanium dioxide） in the PAM （positive active material）. The structural analysis reveals an increase in the tetrabasic lead sulfate and also evidenced by well grown crystals in the PAM with the TiO2, respectively obtained by XRD and SEM techniques. The impedance spectra analysis shows an increase of electrical conductivity of negative active mass with temperature. The battery results showing two fold enhancements in the charge acceptance were attributed to the high surface area activated carbon in the NAM （negative active material）. The materials properties of electrodes and their influence on the battery performance were discussed.
基金supported by the National Natural Science Foundation of China(91433109 and 51472274)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2016)+2 种基金the Program of Guangzhou Science and Technology(201504010031)the Fundamental Research Funds for the Central Universitiesthe Natural Science Foundation of Guangdong Province (S2013030013474 and 2014A030313148)
文摘ABX3-type organic-inorganic hybrid halide perovskite materials have been recognized as promising candidates for optoelectronic applications. However, poor stability of organic-inorganic hybrid perovskite hinders their forward long-term utilization and hence an effective strategy is needed to replace the organic part with an inorganic cation. Herein, all inorganic CsPbI3 nanowires with a di- ameter of 50-100 nm are synthesized on fluorine-doped tin oxide glass via a simple solution-dipping process, which are further transformed into CsPbBr3 nanowires through a so- lution-phase halide exchange method. A phase change from non-perovskite to perovskite structure is observed during the ion substitution process of I- by Br-, which is elaborated by X-ray diffraction, absorption and photoluminescence spectra. We for the first time apply the as-formed CsPbI3 and CsPbBr3 nanowires into perovskite solar cells, yielding power conversion efficiency of 0.11% and 1.21%, respectively. The inorganic CsPbBr3 nanowire solar cell shows impressive sta- bility which still remains 99% of the initial power conversion efficiency even after 5500 h aging.
基金supported by the National Key R&D Program of China(2019YFB1503202)the 111 Project(B16016)+1 种基金the National Natural Science Foundation of China(51702096,U1705256 and 61904053)the Fundamental Research Funds for the Central Universities(2019MS026,2019MS027 and 2020MS080)。
文摘The quality of the perovskite light absorption layer plays a dynamic role in the photovoltaic properties of solar cells.The existing methods to prepare methylammonium lead iodide(MAPbI3)films render substantial structural defect density,particularly at the grain boundaries and film surface,constituting a challenge that hinders the further optoelectronic enhancement of perovskite solar cells.Herein,a unique approach was introduced:using a simple ethylammonium chloride(EACl)additive in perovskite precursor mixture to produce high-quality MAPbI3 thin films.The results indicated that EACl could encourage perovskite crystal growth without experiencing the intermediate phase formation and would evaporate from the perovskite after annealing.Additionally,a gradient perovskite structure was achieved using this technique,which impressively enhanced the performance of the perovskite films.A high power conversion efficiency(PCE)of 20.03%was achieved under the optimal amount of EACl,and the resultant efficient device could retain over 89%of the original PCE after aging for 1000 h at room temperature.This novel technique leads to a facile fabrication of highquality and less-defect perovskite thin films for competent and stable devices.
基金supported by the National Basic Research Program of China (2011CB933300)the National Natural Science Foundation of China (91333107, 51573004)the fund from Shenzhen City (CXZZ20120618162051603)
文摘Organolead trihalide perovskite materials have been attracting increasing attention due to their promising role in solid solar cells. Several advantages make them potential candidates for optoelectronics:(1) solution- or/and vapor-processed preparation at low temperature;(2) tunable optical bandgap, wide absorption spectrum but narrow photoluminescence peaks;(3) long car-rier life time, large diffusion length and high charge mobility;(4) various nanostructures via tuning capping agents and sol-vents. In this review, we summarize recent attempts toward efficient LEDs based on organolead trihalide perovskite materials. The strategies of materials science, device design and interface engineering are highlighted. Recent development and future perspectives are summarized for practical perovskite light technologies.
