The garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid electrolyte is regarded as a promising option for all-solid-state batteries owing to its notable features,including high ionic conductivity and wide electrochemical ...The garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid electrolyte is regarded as a promising option for all-solid-state batteries owing to its notable features,including high ionic conductivity and wide electrochemical window.Although aluminum-doped LLZO(Al-LLZO)is crucial for achieving LLZO ceramics with high critical current density,the characteristics of its grain and grain boundary structures remain largely elusive.In this work,the electrochemical impedance spectroscopy(EIS)technique,in conjunction with the distribution of relaxation times(DRT)method,was employed to investigate structural alterations in Al-LLZO ceramics modified by La_(2)Zr_(2)O_(7)(LZO)additives.Additionally,the impact of sintering temperature and electrolyte testing temperature on ceramic structural changes was investigated using the DRT tools.By optimizing experimental conditions such as the concentration of added LZO and the sintering temperature of Al-LLZO,the study was further refined.This enabled us to successfully identify Al-LLZO solid electrolytes exhibiting uniform morphological structures,moderate crystal grain sizes and high density.By adding 6 wt%of LZO to the Al-LLZO solid electrolyte,we achieved the purest cubic phase and optimal lithium-ion conductivity.Under this condition,the sintered Al-LLZO ceramics exhibited exceeding 4.2×10^(-4)S·cm^(-1)conductivity at room temperature and a high critical current density of up to 0.6 mA·cm^(-2).展开更多
A series of Al-doped silicon-rich silica (AlSiO) composite films have been prepared by a dual ion beam co-sputtering method with a Al, Si and SiO2 composite target. The content of Al and Si in the films can be adjuste...A series of Al-doped silicon-rich silica (AlSiO) composite films have been prepared by a dual ion beam co-sputtering method with a Al, Si and SiO2 composite target. The content of Al and Si in the films can be adjusted by changing the surface area of Al and Si of the target. Visible electroluminescence (EL) from the samples is found to have only one luminescence band peaked at 510 nm (2.4 eV). Experimental results show that the doping of Al is beneficial to reducing the onset voltage and to increasing the intensity of EL.展开更多
Al-doped LiVPO4F cathode materials LiAlxV1-xPO4F were prepared by two-step reactions based on a car-bothermal reduction （CTR） process. The properties of the Al-doped LiVPO4F were investigated by X-ray diffraction （...Al-doped LiVPO4F cathode materials LiAlxV1-xPO4F were prepared by two-step reactions based on a car-bothermal reduction （CTR） process. The properties of the Al-doped LiVPO4F were investigated by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electrochemical measurements. XRD studies show that the Al-doped LiVPO4F has the same triclinic structure （space group p-↑1 ） as the undoped LiVPO4F. The SEM images exhibit that the particle size of Al-doped LiVPO4F is smaller than that of the undoped LiVPO4F and that the smallest particle size is only about 1 μm. The Al-doped LiVPO4F was evaluated as a cathode material for secondary lithium batteries,and exhibited an improved reversibility and cycleability,which may be attributed to the addition of Al^3＋ ion by stabilizing the triclinic structure.展开更多
The electronic structures and elastic properties of Al-doped MoSi2 were calculated using the plane wave pseudo-potential method based on the density functional theory,in which the generalized-gradient approximation(GG...The electronic structures and elastic properties of Al-doped MoSi2 were calculated using the plane wave pseudo-potential method based on the density functional theory,in which the generalized-gradient approximation(GGA) was used to describe the exchange-correlation potential.Starting from the elastic constants,bulk modulus,shear modulus,elastic modulus and Poisson ratio of Al-doped MoSi2 were obtained by using the Hill method.The results indicate that conductivity of Al-doped MoSi2 is improved to some extent in comparison with that of pure MoSi2 due to the orbit hybridization of Mo 4d,Al 3p and Si 3p electrons.In addition,calculations show that the elastic modulus and the brittleness of Al-doped MoSi2 are smaller than those of pure MoSi2,which implies that it is feasible to toughen MoSi2 by doping Al.The agreement of the conclusion with experiment shows that the present theory is reasonable.展开更多
Al-doped carbon nanotubes（Al-doped CNTs） were prepared as a multifunctional integrated material of adsorbent and coagulant aid for organic pollutant removal from aqueous solution. It was observed that aluminum speci...Al-doped carbon nanotubes（Al-doped CNTs） were prepared as a multifunctional integrated material of adsorbent and coagulant aid for organic pollutant removal from aqueous solution. It was observed that aluminum species were dispersed homogeneously on the surface of CNTs, and mainly anchored onto defect structures of the CNTs. The introduction of aluminium efficiently improved adsorption ability for methyl orange（MO） onto the CNTs,and maximum adsorption capacity calculated from the Langmuir isotherm model can reach 69.7 mg/g. The MO adsorption kinetics can be better described by the pseudo-second-order and pore diffusion kinetic models, and the diffusion of MO anions into pores of the Al-doped CNT adsorbent should be the rate-determining step.Thermodynamic analyses indicated that the adsorption of MO onto Al-CNTs-2.0 was endothermic and spontaneous. Moreover, adsorption capacity for MO on the Al-doped CNTs was evidently dependent on the CNT dose, solution p H and adsorbent dose. From the perspective of low-cost and multifunctional, suspension obtained during the Al-doped CNT adsorbent preparation, was tested as coagulant to remove humic acid（HA）. A significant observation is that the suspension exhibited an excellent coagulation performance for HA,because abundant aluminous polymer and Al-doped CNTs existed in the suspension.展开更多
Mesoporous aluminum-doped titanium dioxide(Al-TiO2) materials with high specific surface areas were prepared via a solid-state reaction route.The properties of these materials were characterized by X-ray diffraction(X...Mesoporous aluminum-doped titanium dioxide(Al-TiO2) materials with high specific surface areas were prepared via a solid-state reaction route.The properties of these materials were characterized by X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),energy dispersive spectroscopy(EDS),N2 absorption-desorption,ultraviolet visible light spectroscopy(UV-Vis) and electrochemical spectroscopy.The results show that the mesoporous structure of the product with ethanol is composed of anatase laced crystal walls with amorphous grain boundaries formed gradually by degradation.Compared with those without ethanol,these samples possess larger crystallite size since ethanol decreases the pore size at higher temperature.With the increase of ethanol amount,however,the crystallite size will grow.The amorphous grain boundaries in the mesoporous material,with a large impedance and low incidental cyclic potential,are difficult to effectively degrade and the phase transformation temperature is changed from 500 to 550℃.The growth rate of Al-TiO2 crystallites that obeys the quadratic polynomial equation may be controlled.展开更多
Al-doped zinc-oxide （AZO） thin films treated by oxygen and chlorine inductively coupled plasma （ICP） were compared. Kelvin probe （KP） and X-ray photoelectron spectroscopy （XPS） were employed to characterize th...Al-doped zinc-oxide （AZO） thin films treated by oxygen and chlorine inductively coupled plasma （ICP） were compared. Kelvin probe （KP） and X-ray photoelectron spectroscopy （XPS） were employed to characterize the effect of treatment. The results of KP measurement show that the surface work function of AZO thin films can increase up to 5.92 eV after oxygen ICP （O-ICP）＇s treatment, which means that the work function was increased by at least 1.1 eV. However, after the treatment of chlorine ICP （CI-ICP）, the work function increased to 5.44 eV, and the increment was 0.6 eV. And 10 days later, the work function increment was still 0.4 eV after O-ICP＇s treatment, while the work function after Cl-ICP＇s treatment came back to the original value only after 48 hours. The XPS results suggested that the O-ICP treatment was more effective than CI-ICP for enhancing the work function of AZO films, which is well consistent with KP results.展开更多
In this work, ultrathin pure HfO_2 and Al-doped HfO_2films（about 4-nm thick） are prepared by atomic layer deposition and the crystallinities of these films before and after annealing at temperatures ranging from 550...In this work, ultrathin pure HfO_2 and Al-doped HfO_2films（about 4-nm thick） are prepared by atomic layer deposition and the crystallinities of these films before and after annealing at temperatures ranging from 550℃ to 750℃ are analyzed by grazing incidence x-ray diffraction. The as-deposited pure HfO_2 and Al-doped HfO_2 films are both amorphous. After550-℃ annealing, a multiphase consisting of a few orthorhombic, monoclinic and tetragonal phases can be observed in the pure HfO_2 film while the Al-doped HfO_2 film remains amorphous. After annealing at 650℃ and above, a great number of HfO_2 tetragonal phases, a high-temperature phase with higher dielectric constant, can be stabilized in the Al-doped HfO_2 film. As a result, the dielectric constant is enhanced up to about 35. The physical mechanism of the phase transition behavior is discussed from the viewpoint of thermodynamics and kinetics.展开更多
In this study, series of nanolayered structures of Zn–Al LDHs were prepared by urea hydrolysis. Nanofibers and nanonets of the Al-doped ZnO were formed via the decomposition of the nanolayers under high pressure and ...In this study, series of nanolayered structures of Zn–Al LDHs were prepared by urea hydrolysis. Nanofibers and nanonets of the Al-doped ZnO were formed via the decomposition of the nanolayers under high pressure and temperature. Nanospheres were also prepared for comparison. The different morphologies of the prepared nanomaterials were confirmed by several techniques. An improvement for the optical properties of the doped zinc oxides was observed through narrowing of their band gap energies because of transforming the nanolayers to nanonets and nanofibers. The photocatalytic activities of the prepared nanomaterials were studied through photocatalytic degradation of the pollutants of acid green dyes. Complete decolorization and mineralization of green dyes happened in the presence of the nanolayers and nanospheres within 4–6 h,while the nanonets and the nanofibers achieved the complete decolorization and degradation of the dyes at shorter time 1.3 h. These results could be explained though the kinetic study of the photocatalytic degradation of dyes. It was concluded that the nanonets and the nanofibers were very effective for the photocatalytic degradation of pollutants.展开更多
Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching process...Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching processes, which must be overcome for the application of AZO in various devices. Therefore, in this study, the etch rate and surface properties of an AZO thin film after plasma etching using the adaptive coupled plasma system were investigated. The fastest etch rate was achieved with a CF_(4)/Ar ratio of 50:50 sccm. Regardless of the ratio of CF_(4) to Ar,the transmittance of the film in the visible region exceeded 80%. X-ray photoelectron spectroscopy analysis of the AZO thin film confirmed that metal-F bonding persists on the surface after plasma etching. It was also shown that F eliminates O vacancies. Consequently, the work function and bandgap energy increased as the ratio of CF-4 increased. This study not only provides information on the effect of plasma on AZO thin film, but identifies the cause of changes in the device characteristics during device fabrication.展开更多
AlGaN/GaN high-electron-mobility transistors （HEMTs） with Al-doped ZnO （AZO） transparent gate electrodes are fabricated, and Ni/Au/Ni-gated HEMTs are produced in comparison. The AZO-gated HEMTs show good DC charac...AlGaN/GaN high-electron-mobility transistors （HEMTs） with Al-doped ZnO （AZO） transparent gate electrodes are fabricated, and Ni/Au/Ni-gated HEMTs are produced in comparison. The AZO-gated HEMTs show good DC characteristics and Schottky rectifying characteristics, and the gate electrodes achieve excellent transparencies. Compared with Ni/Au/Ni-gated HEMTs, AZO-gated HEMTs show a low saturation current, high threshold voltage, high Schottky barrier height, and low gate reverse leakage current. Due to the higher gate resistivity, AZO-gated HEMTs exhibit a current-gain cutoff frequency （fT） of 10 GHz and a power gain cutoff frequency （fmax） of 5 GHz, and lower maximum oscillation frequency than Ni/Au/Ni-gated HEMTs. Moreover, the C-V characteristics are measured and the gate interface characteristics of the AZO-gated devices are investigated by a C-V dual sweep.展开更多
We report a back-gated metal-oxide-ferroelectric-metal （MOFM） field-effect transistor （FET） with lead zirconate titanate （PZT） material, in which an Al doped zinc oxide （AZO） channel layer with an optimized do...We report a back-gated metal-oxide-ferroelectric-metal （MOFM） field-effect transistor （FET） with lead zirconate titanate （PZT） material, in which an Al doped zinc oxide （AZO） channel layer with an optimized doping concentration of 1% is applied to reduce the channel resistance of the channel layer, thus guaranteeing a large enough load capacity of the transistor. The hysteresis loops of the Pt/PZT/AZO/Ti/Pt capacitor are measured and compared with a Pt/PZT/Pt capacitor, indicating that the remnant polarization is almost 40 μC/cm^2 and the polarization is saturated at 20 V. The measured capacitance-voltage properties are analyzed as a result of the electron depletion and accumulation switching operation conducted by the modulation of PZT on AZO channel resistance caused by the switchable remnant polarization of PZT. The switching properties of the AZO channel layer are also proved by the current-voltage transfer curves measured in the back-gated MOFM ferroelectric FET, which also show a drain current switching ratio up to about 100 times.展开更多
Single phase polycrystalline samples Na0.7Co1-xAlxO2 （x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 030） were prepared by solid state reaction. The magnetic properties from 5 K to 300 K have been studied by dc and ac magneti...Single phase polycrystalline samples Na0.7Co1-xAlxO2 （x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 030） were prepared by solid state reaction. The magnetic properties from 5 K to 300 K have been studied by dc and ac magnetic susceptibility measurements. Samples with lower doping quantity （x = 0, 0.05, 0.10） showed paramagnetic behaviors, but those with higher doping quantity （x=0.20, 0.25, 0.30）showed spin-glass behaviors with a freezing temperature （Tf） of about 13 K.展开更多
The increasing demand for energy density pushes Li CoO_(2)(LCO)to work at higher voltage(≥4.5 V),which brings a series of problems including detrimental phase transition and structural instability.Various el emental ...The increasing demand for energy density pushes Li CoO_(2)(LCO)to work at higher voltage(≥4.5 V),which brings a series of problems including detrimental phase transition and structural instability.Various el emental doping has been proven an effective strategy to improve its structure stability.However,the understanding of elemental doping homogeneity effect is not enough,whether in terms of the controlla bility of doping homogeneity or its complex consequences.In this work,LCO powders with different A doping homogeneity were synthesized and tested under high voltage(≥4.5 V)in both half and full cell a room and high temperature,respectively.The results show that the Al homogeneously doped LCO showed better cycling stability and rate performance compared to the inhomogeneous LCO sample.Particularly the discharge capacity of Al homogeneously doped LCO after 500 cycles under 4.5 V in full cells could reach 160.1 mAh/g at 1.0 C with 94.1%capacity retention.Postmortem characterization demonstrates tha a better doping homogeneity favors the stability of both the bulk and interface as well as the kinetic conditions.This study provided new insights about LCO performance fading,which sheds new light on the development of high-voltage LCO products.展开更多
Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of a...Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target. The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively. Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films. The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase. Effects of crystallinity, surface roughness, PL on the transmittance of the AZO films were also explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results.展开更多
Aluminum-doped zinc oxide （ZnO：Al）, abbreviated as ZAO, is a novel and widely used transparent conductive material. The ZAO powder was synthesized by chemical coprecipitation. The ZAO ceramic sputtering target mate...Aluminum-doped zinc oxide （ZnO：Al）, abbreviated as ZAO, is a novel and widely used transparent conductive material. The ZAO powder was synthesized by chemical coprecipitation. The ZAO ceramic sputtering target materials were fabricated by sintering in air, and ZAO transparent conductive films were prepared by RF magnetron sputtering on glass substrates. XRD proved that such films had an orientation of （002） crystal panel paralleled to the surface of the glass substrate. The average transmittance of the films in the visible region exceeded 80%.展开更多
Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） proc...Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO （1：1） thin film deposited at 400 ~C shows the electrical resistivity of 4.18 x 10 4 ~.cm, an electron concentration of 7.5 x 1020/cm3, and carrier mobility of 25.4 cm2/（V.s）. The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the AI ratio.展开更多
Al-doped zinc oxide （ZnO：Al,AZO） films were deposited on glass substrates using a reactive mid-frequency （MF） magnetron sputtering process with rotating cathodes.The influence of deposition parameters on structur...Al-doped zinc oxide （ZnO：Al,AZO） films were deposited on glass substrates using a reactive mid-frequency （MF） magnetron sputtering process with rotating cathodes.The influence of deposition parameters on structural,electrical and optical properties of AZO films is investigated.It is observed that the rotating magnetron targets exhibited a sputtered metallic surface over a wider range,and there is no re-deposition zone between the racetracks.The films deposited at static deposition mode demonstrate more homogenous in thickness and resistivity across the target surface compared with conventional rectangular targets.The films deposited under the proper conditions show a regular cone-shaped grain surface and densely packed columnar structure.The minimum resistivity of 3.16×10-4 ·cm was obtained for the film prepared at substrate temperature of 150 C,gas pressure of 640 MPa and oxygen partial pressure of 34 MPa.展开更多
Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from ...Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a （002） preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.展开更多
Transparent conductive aluminum doped zinc oxide（ZnO：Al,AZO） films were prepared on glass substrates by rf（radio frequency） magnetron sputtering from ZnO： 3wt% Al_2O_3 ceramic target. The effect of argon gas pre...Transparent conductive aluminum doped zinc oxide（ZnO：Al,AZO） films were prepared on glass substrates by rf（radio frequency） magnetron sputtering from ZnO： 3wt% Al_2O_3 ceramic target. The effect of argon gas pressure（PAr） was investigated with small variations to understand the influence on the electrical, optical and structural properties of the films. Structural examinations using X-ray diffraction（XRD） and scanning electron microscopy（SEM） showed that the ZnO：Al thin films were（002） oriented. The resistivity values were measured by four-point probe with the lowest resistivity of 5.76×10^（-4） Ω？cm（sheet resistance=9.6 Ω/sq. for a thickness=600 nm） obtained at the PAr of 0.3 Pa. The transmittance was achieved from ultravioletvisible（UV-VIS） spectrophotometer, 84% higher than that in the visible region for all AZO thin films. The properties of deposited thin films showed a significant dependence on the PAr.展开更多
基金supported by the National Natural Science Foundation of China(No.52102284)the Science and Technology Project of Shenzhen(Nos.JCYJ20210324094206019 and JCYJ20210324094000001).
文摘The garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid electrolyte is regarded as a promising option for all-solid-state batteries owing to its notable features,including high ionic conductivity and wide electrochemical window.Although aluminum-doped LLZO(Al-LLZO)is crucial for achieving LLZO ceramics with high critical current density,the characteristics of its grain and grain boundary structures remain largely elusive.In this work,the electrochemical impedance spectroscopy(EIS)technique,in conjunction with the distribution of relaxation times(DRT)method,was employed to investigate structural alterations in Al-LLZO ceramics modified by La_(2)Zr_(2)O_(7)(LZO)additives.Additionally,the impact of sintering temperature and electrolyte testing temperature on ceramic structural changes was investigated using the DRT tools.By optimizing experimental conditions such as the concentration of added LZO and the sintering temperature of Al-LLZO,the study was further refined.This enabled us to successfully identify Al-LLZO solid electrolytes exhibiting uniform morphological structures,moderate crystal grain sizes and high density.By adding 6 wt%of LZO to the Al-LLZO solid electrolyte,we achieved the purest cubic phase and optimal lithium-ion conductivity.Under this condition,the sintered Al-LLZO ceramics exhibited exceeding 4.2×10^(-4)S·cm^(-1)conductivity at room temperature and a high critical current density of up to 0.6 mA·cm^(-2).
基金This work was supported by the National Natural Science Foundation of China (Grant No. 69876043) Shanghai Insti- tute of Metallurgy, the Chinese Academy of Sciences.
文摘A series of Al-doped silicon-rich silica (AlSiO) composite films have been prepared by a dual ion beam co-sputtering method with a Al, Si and SiO2 composite target. The content of Al and Si in the films can be adjusted by changing the surface area of Al and Si of the target. Visible electroluminescence (EL) from the samples is found to have only one luminescence band peaked at 510 nm (2.4 eV). Experimental results show that the doping of Al is beneficial to reducing the onset voltage and to increasing the intensity of EL.
文摘Al-doped LiVPO4F cathode materials LiAlxV1-xPO4F were prepared by two-step reactions based on a car-bothermal reduction （CTR） process. The properties of the Al-doped LiVPO4F were investigated by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electrochemical measurements. XRD studies show that the Al-doped LiVPO4F has the same triclinic structure （space group p-↑1 ） as the undoped LiVPO4F. The SEM images exhibit that the particle size of Al-doped LiVPO4F is smaller than that of the undoped LiVPO4F and that the smallest particle size is only about 1 μm. The Al-doped LiVPO4F was evaluated as a cathode material for secondary lithium batteries,and exhibited an improved reversibility and cycleability,which may be attributed to the addition of Al^3＋ ion by stabilizing the triclinic structure.
基金Project(20080431025) supported by Chinese Postdoctoral Science FoundationProject(08JJ3005) supported by Hunan Provincial Natural Science Foundation of ChinaProject(2007) supported by Postdoctoral Science Foundation of Central South University,China
文摘The electronic structures and elastic properties of Al-doped MoSi2 were calculated using the plane wave pseudo-potential method based on the density functional theory,in which the generalized-gradient approximation(GGA) was used to describe the exchange-correlation potential.Starting from the elastic constants,bulk modulus,shear modulus,elastic modulus and Poisson ratio of Al-doped MoSi2 were obtained by using the Hill method.The results indicate that conductivity of Al-doped MoSi2 is improved to some extent in comparison with that of pure MoSi2 due to the orbit hybridization of Mo 4d,Al 3p and Si 3p electrons.In addition,calculations show that the elastic modulus and the brittleness of Al-doped MoSi2 are smaller than those of pure MoSi2,which implies that it is feasible to toughen MoSi2 by doping Al.The agreement of the conclusion with experiment shows that the present theory is reasonable.
基金supported by the National Natural Science Foundation of China(No.21407152)
文摘Al-doped carbon nanotubes（Al-doped CNTs） were prepared as a multifunctional integrated material of adsorbent and coagulant aid for organic pollutant removal from aqueous solution. It was observed that aluminum species were dispersed homogeneously on the surface of CNTs, and mainly anchored onto defect structures of the CNTs. The introduction of aluminium efficiently improved adsorption ability for methyl orange（MO） onto the CNTs,and maximum adsorption capacity calculated from the Langmuir isotherm model can reach 69.7 mg/g. The MO adsorption kinetics can be better described by the pseudo-second-order and pore diffusion kinetic models, and the diffusion of MO anions into pores of the Al-doped CNT adsorbent should be the rate-determining step.Thermodynamic analyses indicated that the adsorption of MO onto Al-CNTs-2.0 was endothermic and spontaneous. Moreover, adsorption capacity for MO on the Al-doped CNTs was evidently dependent on the CNT dose, solution p H and adsorbent dose. From the perspective of low-cost and multifunctional, suspension obtained during the Al-doped CNT adsorbent preparation, was tested as coagulant to remove humic acid（HA）. A significant observation is that the suspension exhibited an excellent coagulation performance for HA,because abundant aluminous polymer and Al-doped CNTs existed in the suspension.
基金Supported by the National Natural Science Foundation of China （21061006） the Research of Natural Science and Technology Foundation of Guizhou Province （[2010]2006） the Graduate Scientific Innovation Project of Education Department of Guangxi Autonomous Region （1059330901009）
文摘Mesoporous aluminum-doped titanium dioxide(Al-TiO2) materials with high specific surface areas were prepared via a solid-state reaction route.The properties of these materials were characterized by X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),energy dispersive spectroscopy(EDS),N2 absorption-desorption,ultraviolet visible light spectroscopy(UV-Vis) and electrochemical spectroscopy.The results show that the mesoporous structure of the product with ethanol is composed of anatase laced crystal walls with amorphous grain boundaries formed gradually by degradation.Compared with those without ethanol,these samples possess larger crystallite size since ethanol decreases the pore size at higher temperature.With the increase of ethanol amount,however,the crystallite size will grow.The amorphous grain boundaries in the mesoporous material,with a large impedance and low incidental cyclic potential,are difficult to effectively degrade and the phase transformation temperature is changed from 500 to 550℃.The growth rate of Al-TiO2 crystallites that obeys the quadratic polynomial equation may be controlled.
基金supported by National Natural Science Foundation of China(Nos.1100502151177017 and 11175049)+1 种基金the Fudan University Excellent Doctoral Research Program(985 Project) the Ph.D Programs Foundation of Ministry of Education of China(No.20120071110031)
文摘Al-doped zinc-oxide （AZO） thin films treated by oxygen and chlorine inductively coupled plasma （ICP） were compared. Kelvin probe （KP） and X-ray photoelectron spectroscopy （XPS） were employed to characterize the effect of treatment. The results of KP measurement show that the surface work function of AZO thin films can increase up to 5.92 eV after oxygen ICP （O-ICP）＇s treatment, which means that the work function was increased by at least 1.1 eV. However, after the treatment of chlorine ICP （CI-ICP）, the work function increased to 5.44 eV, and the increment was 0.6 eV. And 10 days later, the work function increment was still 0.4 eV after O-ICP＇s treatment, while the work function after Cl-ICP＇s treatment came back to the original value only after 48 hours. The XPS results suggested that the O-ICP treatment was more effective than CI-ICP for enhancing the work function of AZO films, which is well consistent with KP results.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2015AA016501)the National Natural Science Foundation of China(Grant Nos.61574168 and 61504163)
文摘In this work, ultrathin pure HfO_2 and Al-doped HfO_2films（about 4-nm thick） are prepared by atomic layer deposition and the crystallinities of these films before and after annealing at temperatures ranging from 550℃ to 750℃ are analyzed by grazing incidence x-ray diffraction. The as-deposited pure HfO_2 and Al-doped HfO_2 films are both amorphous. After550-℃ annealing, a multiphase consisting of a few orthorhombic, monoclinic and tetragonal phases can be observed in the pure HfO_2 film while the Al-doped HfO_2 film remains amorphous. After annealing at 650℃ and above, a great number of HfO_2 tetragonal phases, a high-temperature phase with higher dielectric constant, can be stabilized in the Al-doped HfO_2 film. As a result, the dielectric constant is enhanced up to about 35. The physical mechanism of the phase transition behavior is discussed from the viewpoint of thermodynamics and kinetics.
基金the Deanship of Scientific Research in King Faisal University (Saudi Arabia) for funding and providing the facilities required for this research as a part of Annual Research Grants Program (No. 170047)
文摘In this study, series of nanolayered structures of Zn–Al LDHs were prepared by urea hydrolysis. Nanofibers and nanonets of the Al-doped ZnO were formed via the decomposition of the nanolayers under high pressure and temperature. Nanospheres were also prepared for comparison. The different morphologies of the prepared nanomaterials were confirmed by several techniques. An improvement for the optical properties of the doped zinc oxides was observed through narrowing of their band gap energies because of transforming the nanolayers to nanonets and nanofibers. The photocatalytic activities of the prepared nanomaterials were studied through photocatalytic degradation of the pollutants of acid green dyes. Complete decolorization and mineralization of green dyes happened in the presence of the nanolayers and nanospheres within 4–6 h,while the nanonets and the nanofibers achieved the complete decolorization and degradation of the dyes at shorter time 1.3 h. These results could be explained though the kinetic study of the photocatalytic degradation of dyes. It was concluded that the nanonets and the nanofibers were very effective for the photocatalytic degradation of pollutants.
基金supported by the National Research Foundation (NRF) of Korea (Nos. 2018R1D1A1B07051429 and 2020R1G1A1102692)。
文摘Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching processes, which must be overcome for the application of AZO in various devices. Therefore, in this study, the etch rate and surface properties of an AZO thin film after plasma etching using the adaptive coupled plasma system were investigated. The fastest etch rate was achieved with a CF_(4)/Ar ratio of 50:50 sccm. Regardless of the ratio of CF_(4) to Ar,the transmittance of the film in the visible region exceeded 80%. X-ray photoelectron spectroscopy analysis of the AZO thin film confirmed that metal-F bonding persists on the surface after plasma etching. It was also shown that F eliminates O vacancies. Consequently, the work function and bandgap energy increased as the ratio of CF-4 increased. This study not only provides information on the effect of plasma on AZO thin film, but identifies the cause of changes in the device characteristics during device fabrication.
基金supported by the National Key Science & Technology Special Project (Grant No. 2008ZX01002-002)the National Natural Science Foundation of China (Grant No. 61106106)the Fundamental Research Funds for the Central Universities,China (Grant Nos. K50510250003 and K50510250006)
文摘AlGaN/GaN high-electron-mobility transistors （HEMTs） with Al-doped ZnO （AZO） transparent gate electrodes are fabricated, and Ni/Au/Ni-gated HEMTs are produced in comparison. The AZO-gated HEMTs show good DC characteristics and Schottky rectifying characteristics, and the gate electrodes achieve excellent transparencies. Compared with Ni/Au/Ni-gated HEMTs, AZO-gated HEMTs show a low saturation current, high threshold voltage, high Schottky barrier height, and low gate reverse leakage current. Due to the higher gate resistivity, AZO-gated HEMTs exhibit a current-gain cutoff frequency （fT） of 10 GHz and a power gain cutoff frequency （fmax） of 5 GHz, and lower maximum oscillation frequency than Ni/Au/Ni-gated HEMTs. Moreover, the C-V characteristics are measured and the gate interface characteristics of the AZO-gated devices are investigated by a C-V dual sweep.
基金Supported by the Fundamental Research Funds for the Central Universities of China
文摘We report a back-gated metal-oxide-ferroelectric-metal （MOFM） field-effect transistor （FET） with lead zirconate titanate （PZT） material, in which an Al doped zinc oxide （AZO） channel layer with an optimized doping concentration of 1% is applied to reduce the channel resistance of the channel layer, thus guaranteeing a large enough load capacity of the transistor. The hysteresis loops of the Pt/PZT/AZO/Ti/Pt capacitor are measured and compared with a Pt/PZT/Pt capacitor, indicating that the remnant polarization is almost 40 μC/cm^2 and the polarization is saturated at 20 V. The measured capacitance-voltage properties are analyzed as a result of the electron depletion and accumulation switching operation conducted by the modulation of PZT on AZO channel resistance caused by the switchable remnant polarization of PZT. The switching properties of the AZO channel layer are also proved by the current-voltage transfer curves measured in the back-gated MOFM ferroelectric FET, which also show a drain current switching ratio up to about 100 times.
基金This work was supported by the National Science Foundation of China under Grant No. 50372052, 50430137, 50588201 the National Basic Research Program of China (973 program), under Grant No. 2007CB616906)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in UniversityAustralian Research Council under Grant No. DP0559872, DP0881739.
文摘Single phase polycrystalline samples Na0.7Co1-xAlxO2 （x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 030） were prepared by solid state reaction. The magnetic properties from 5 K to 300 K have been studied by dc and ac magnetic susceptibility measurements. Samples with lower doping quantity （x = 0, 0.05, 0.10） showed paramagnetic behaviors, but those with higher doping quantity （x=0.20, 0.25, 0.30）showed spin-glass behaviors with a freezing temperature （Tf） of about 13 K.
基金supported by the National Natural Science Foundation of China(No.52122407)the Science and Technology Innovation Program of Hunan Province(No.2022RC3048)the Key Research and Development Program of Yunnan Province(No.202103AA080019)。
文摘The increasing demand for energy density pushes Li CoO_(2)(LCO)to work at higher voltage(≥4.5 V),which brings a series of problems including detrimental phase transition and structural instability.Various el emental doping has been proven an effective strategy to improve its structure stability.However,the understanding of elemental doping homogeneity effect is not enough,whether in terms of the controlla bility of doping homogeneity or its complex consequences.In this work,LCO powders with different A doping homogeneity were synthesized and tested under high voltage(≥4.5 V)in both half and full cell a room and high temperature,respectively.The results show that the Al homogeneously doped LCO showed better cycling stability and rate performance compared to the inhomogeneous LCO sample.Particularly the discharge capacity of Al homogeneously doped LCO after 500 cycles under 4.5 V in full cells could reach 160.1 mAh/g at 1.0 C with 94.1%capacity retention.Postmortem characterization demonstrates tha a better doping homogeneity favors the stability of both the bulk and interface as well as the kinetic conditions.This study provided new insights about LCO performance fading,which sheds new light on the development of high-voltage LCO products.
文摘Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target. The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively. Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films. The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase. Effects of crystallinity, surface roughness, PL on the transmittance of the AZO films were also explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results.
文摘Aluminum-doped zinc oxide （ZnO：Al）, abbreviated as ZAO, is a novel and widely used transparent conductive material. The ZAO powder was synthesized by chemical coprecipitation. The ZAO ceramic sputtering target materials were fabricated by sintering in air, and ZAO transparent conductive films were prepared by RF magnetron sputtering on glass substrates. XRD proved that such films had an orientation of （002） crystal panel paralleled to the surface of the glass substrate. The average transmittance of the films in the visible region exceeded 80%.
基金supported by the Yeungnam University Research Grants in 2009
文摘Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO （1：1） thin film deposited at 400 ~C shows the electrical resistivity of 4.18 x 10 4 ~.cm, an electron concentration of 7.5 x 1020/cm3, and carrier mobility of 25.4 cm2/（V.s）. The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the AI ratio.
文摘Al-doped zinc oxide （ZnO：Al,AZO） films were deposited on glass substrates using a reactive mid-frequency （MF） magnetron sputtering process with rotating cathodes.The influence of deposition parameters on structural,electrical and optical properties of AZO films is investigated.It is observed that the rotating magnetron targets exhibited a sputtered metallic surface over a wider range,and there is no re-deposition zone between the racetracks.The films deposited at static deposition mode demonstrate more homogenous in thickness and resistivity across the target surface compared with conventional rectangular targets.The films deposited under the proper conditions show a regular cone-shaped grain surface and densely packed columnar structure.The minimum resistivity of 3.16×10-4 ·cm was obtained for the film prepared at substrate temperature of 150 C,gas pressure of 640 MPa and oxygen partial pressure of 34 MPa.
基金Funded by Key Project of Natural Science Foundation of Hubei Province(No.2008CDA025)
文摘Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a （002） preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.
基金Funded by the Key Projects in the National Science&Technology Pillar Program during the Twelfth Five-year Plan Period(No.2011BAJ04B04)
文摘Transparent conductive aluminum doped zinc oxide（ZnO：Al,AZO） films were prepared on glass substrates by rf（radio frequency） magnetron sputtering from ZnO： 3wt% Al_2O_3 ceramic target. The effect of argon gas pressure（PAr） was investigated with small variations to understand the influence on the electrical, optical and structural properties of the films. Structural examinations using X-ray diffraction（XRD） and scanning electron microscopy（SEM） showed that the ZnO：Al thin films were（002） oriented. The resistivity values were measured by four-point probe with the lowest resistivity of 5.76×10^（-4） Ω？cm（sheet resistance=9.6 Ω/sq. for a thickness=600 nm） obtained at the PAr of 0.3 Pa. The transmittance was achieved from ultravioletvisible（UV-VIS） spectrophotometer, 84% higher than that in the visible region for all AZO thin films. The properties of deposited thin films showed a significant dependence on the PAr.
