Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+),Cr^(3+)(YAGG:Ce^(3+),Cr^(3+)),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent lumine...Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+),Cr^(3+)(YAGG:Ce^(3+),Cr^(3+)),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent luminescent material applications.At present,YAGG:Ce^(3+),Cr^(3+)powders exhibit good persistent performance,but their persistent performance of ceramics still needs to be further improved to meet the new requirements.In this work,(Y_(0.998)Ce_(0.002))_(3)(Al_(1-x)Cr_(x))_(2)Ga_(3)O_(12) ceramics with different Cr^(3+)doping concentrations were prepared by solid-state reaction,including air pre-sintering,hot isostatic pressing(HIP)post-treatment and air annealing,to investigate the effects of Cr^(3+)doping concentration on the microstructure,optical properties and persistent performance of the ceramics.The results showed that as the doping concentration of Cr^(3+)increased from 0.025%to 0.2%(in atom),no significant effect of Cr^(3+)concentration on the morphology of pre-sintered ceramics or HIP post-treatment ceramics was observed,but the in-line transmittance gradually increased while the persistent performance gradually decreased.Among them,YAGG:Ce^(3+),Cr^(3+)ceramics doped with 0.025%Cr^(3+)showed the strongest initial luminescence intensity exceeding 6055 mcd/m^(2) and a persistent time of 1030 min after air pre-sintering combined with HIP post-treatment and air annealing.By optimizing the Cr^(3+)doping concentration and the fabrication process,the persistent luminescence(PersL)performance of the YAGG:Ce^(3+),Cr^(3+)ceramics was obviously improved.展开更多
A solid state reaction method was used to prepare the perovskite-structured compounds BaZrl-xYxO3-a （x=0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3）. The X-ray diffraction （XRD） pattern indicated that the target perovsldte ...A solid state reaction method was used to prepare the perovskite-structured compounds BaZrl-xYxO3-a （x=0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3）. The X-ray diffraction （XRD） pattern indicated that the target perovsldte phases were obtained. With increasing Y con- centration the unit cell parameters of BaZrl-xYxO3-a samples were expanded, and Y doping became more difficult. However, high synthesis temperature is helpful to promote Y doping. The SEM results showed that the samples exhibited poor sinterability with in- creasing Y-doping content. Thermal gravimetric （TG） curves analysis showed the more mass decreasing of BaZrl-xYxO3-a （0≤x≤0.3） samples at high temperature with more Y doping and more proton introducing. The electrochemical impedance spectra （EIS） of specimens showed that conductivities of BaZrl_xYxO3（0≤x≤0.3） increased with increasing temperature from 300 to 900 ℃ in wet air. At 900 ℃, the conductivity of BaZrl-xYxO3-a （0≤x≤0.3） first increased with increasing doped amount of Y, and reached the high- est value of 1.07x 104 S/cm when x was 0.2, then decreased gradually with further increasing Y content. At 600 ℃, BaZr0.75Y0.2503-a displayed the highest conductivity, while the conductivity of BaZro.rYo.303-a was the highest at 300 ℃. The results indicated that there should be an optimum Y doping concentration yielding the highest conductivity at a constant temperature, and the optimum Y doping concentration should increase in the humidity atmosphere as the temperature decreases. So increasing the Y-doping concen- tration is helpful to improve the conductivities of BaZrl-xYxO3-a materials at low temperature.展开更多
Catalytic oxidation of formaldehyde (HCHO) is the most efficient way to purify indoor air of HCHO pollutant. This work investigated rare earth La‐doped Pt/TiO2 for low concentration HCHO oxidation at room temperature...Catalytic oxidation of formaldehyde (HCHO) is the most efficient way to purify indoor air of HCHO pollutant. This work investigated rare earth La‐doped Pt/TiO2 for low concentration HCHO oxidation at room temperature. La‐doped Pt/TiO2 had a dramatically promoted catalytic performance for HCHO oxidation. The reasons for the La promotion effect were investigated by N2 adsorption, X‐raydiffraction, CO chemisorption, X‐ray photoelectron spectroscopy, transmission electron microscopy(TEM) and high‐angle annular dark field scanning TEM. The Pt nanoparticle size was reduced to 1.7nm from 2.2 nm after modification by La, which led to higher Pt dispersion, more exposed activesites and enhanced metal‐support interaction. Thus a superior activity for indoor low concentrationHCHO oxidation was obtained. Moreover, the La‐doped TiO2 can be wash‐coated on a cordieritemonolith so that very low amounts of Pt (0.01 wt%) can be used. The catalyst was evaluated in asimulated indoor HCHO elimination environment and displayed high purifying efficiency and stability.It can be potentially used as a commercial catalyst for indoor HCHO elimination.展开更多
SrTi1-yMgyO3 films were synthesized through sol-gel method on p^+-Si substrates. The effects of Mg doping concentration on the microstructure, switching behavior and properties of SrTi1-yMgyO3 films were investigated....SrTi1-yMgyO3 films were synthesized through sol-gel method on p^+-Si substrates. The effects of Mg doping concentration on the microstructure, switching behavior and properties of SrTi1-yMgyO3 films were investigated. All SrTi1-yMgyO3 films are polycrystalline, but the grain becomes coarser, and the number of holes is reduced when the Mg doping content increases from 0.04 to 0.16. SrTi1-yMgyO3 films with different Mg doping concentrations all show bipolar resistive switching behaviors but display some differences in switching properties. When y=0.08, the SrTi1-yMgyO3 films show the largest RHRS/RLRS of 105 and better fatigue endurance after 103 cycles. When y≥0.08, the distribution of Vset and Vreset is narrow, indicating good stability of writing and erasing data for a resistive random access memory. At high-resistance state, the dominant conduction mechanism of SrTi1-yMgyO3 films is the Schottky emission mechanism. However, at low-resistance state, the dominant conduction mechanisms are the filamentary conduction and changes to space charge limited current when y=0.16.展开更多
A novel type of n/i/i/p heterojunction solar cell with a-Si：H（15 nm）/a-Si：H（10 nm）/epitaxial c-Si（47 p.m）/epitaxial c-Si（3 um） structure is fabricated by using the layer transfer technique, and the emitter l...A novel type of n/i/i/p heterojunction solar cell with a-Si：H（15 nm）/a-Si：H（10 nm）/epitaxial c-Si（47 p.m）/epitaxial c-Si（3 um） structure is fabricated by using the layer transfer technique, and the emitter layer is deposited by hot wire chemical vapour deposition. The effect of the doping concentration of the emitter layer Sd （Sd=PH3/（PH3 ＋SiH4＋H2）） on the performance of the solar cell is studied by means of current density-voltage and external quantum efficiency. The results show that the conversion efficiency of the solar cell first increases to a maximum value and then decreases with Sd increasing from 0.1% to 0.4%. The best performance of the solar cell is obtained at Sd = 0.2% with an open circuit voltage of 534 mV, a short circuit current density of 23.35 mA/cm2, a fill factor of 63.3%, and a conversion efficiency of 7.9%.展开更多
The main purpose of this work is to study doping level effects on a silicon PV cell under both moderate light concentration and normal illumination. This study also aims to compare the doping level effects under the b...The main purpose of this work is to study doping level effects on a silicon PV cell under both moderate light concentration and normal illumination. This study also aims to compare the doping level effects under the both illumination modes. The results show for both illumination modes that diffusion parameters decrease with increasing doping level. These results are in agreement with the studies of the current and the voltage which showed for the two illumination modes that doping level increase leads to a decrease in current density and an increase in voltage. It also emerges for the two illumination modes and for the doping range 10<sup>13</sup> cm<sup>-3</sup> - 10<sup>16</sup> cm<sup>-3</sup>, a decrease of maximum power and conversion efficiency. The results also show that decrease of diffusion parameters is faster under moderate concentration in comparison with normal illumination. These results predict a greater variation rate of the current, the voltage, the maximum power and the conversion efficiency under moderate concentration compared to normal illumination. Contrary to diffusion parameters study, the results show higher variation rates of parameters under normal illumination. This is explained by the fact that under moderate concentration, carriers density is close to doping level: the cell is then in high injection condition. Consequently, under moderate concentration, carriers density is less sensitive to doping level variations. The study confirms that carriers density variation with the doping level is weak under the moderate concentration compared to normal illumination.展开更多
Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its exceptional plasticity and promising thermoelectric performance.Howev...Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its exceptional plasticity and promising thermoelectric performance.However,the low carrier concentration severely limits its thermoelectric performance improvement.In this work,we conducted contrasting strategies that can be employed to increase the carrier concentration of InSe,including bandgap narrowing and heterovalent doping.Specifically,the carrier concentration initially increases as a result of the reduced bandgap upon Te alloying and then slightly decreases due to the weak electronegativity of Te.Whereas Br doping realizes high carrier concentration by pushing the Fermi level into the conduction bands and activating the multiple bands.On the other hand,both Te and Br obviously suppress the thermal conductivity due to the point defect scattering.By contrast,Br doping realizes a higher thermoelectric performance with a maximum ZT of~0.13 at 773 K benefiting from the better optimization of carrier concentration.This work elucidates the strategies for enhancing carrier concentration at anion sites and demonstrates the high efficiency of halogen doping in InSe.Moreover,the carrier concentration of InSe is promising to be further optimized,and future work should focus on employing approaches such as cation doping or secondphase compositing.展开更多
In this study, we investigate some main electrical parameters of the gold/poly（3-hexylthiophene）：[6,6]-phenyl C61 bu- tyric acid methyl ester：2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane/n-type silicon （A...In this study, we investigate some main electrical parameters of the gold/poly（3-hexylthiophene）：[6,6]-phenyl C61 bu- tyric acid methyl ester：2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane/n-type silicon （Au/P3HT：PCBM：F4-TCNQ/n- Si） metal-polymer-semiconductor （MPS） Schottky barrier diode （SBD） in terms of the effects of F4-TCNQ concentration （0%, 1%, and 2%）. F4-TCNQ-doped P3HT：PCBM is fabricated to figure out the p-type doping effect on the device per- formance. The main electrical parameters, such as ideality factor （n）, barrier height （ФB0）, series resistance （Rs）, shunt resistance （Rsh）, and density of interface states （Nss） are determined from the forward and reverse bias current-voltage （l-V） characteristics in the dark and at room temperature. The values of n, Rs, ФB0, and Nss are significantly reduced by using the 1% F4-TCNQ doping in P3HT：PCBM：F4-TCNQ organic blend layer, additionally, the carrier mobility and current are increased by the soft （1%） doping. The most ideal values of electrical parameters are obtained for 1% F4-TCNQ used diode. On the other hand, the carrier mobility and current for the hard doping （2%） become far away from the ideal diode values due to the unbalanced generation of holes/electrons and doping-induced disproportion when compared with 1% F4-TCNQ doping. These results show that the electrical properties of MPS SBDs strongly depend on the F4-TCNQ doping and doping concentration of interfacial P3HT：PCBM：F4-TCNQ organic layer. Moreover, the soft F4-TCNQ dop- ing concentration （1%） in P3HT：PCBM：F4-TCNQ organic layer significantly improves the electrical characteristics of the Au/P3HT：PCBM：F4-TCNQ/n-Si （MPS） SBDs which enables the fabricating of high-quality electronic and optoelectronic devices.展开更多
The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results...The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900℃and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43 .34 nm.展开更多
The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,...The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,the intrinsically p-type Mg3Sb2 shows low figure of merit（z T = 0.23 at 723 K） for its poor electrical conductivity.In this study,a series of Mg（3-x）LixSb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering（SPS） process.Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample,which can be essentially attributed to the increased carrier concentration,leading to a maximum z T of0.59 at 723 K with the optimum doping level x = 0.01.Additionally,the engineering z T and energy conversion efficiency are calculated to be 0.235 and 4.89%,respectively.To our best knowledge,those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.展开更多
For high-repetition-rate nanosecond high-power solid-state lasers,it is essential to choose gain media with moderate saturation flux.Among these materials,Nd:Lu_(3)Al_(5)O_(12)(LuAG)transparent ceramics have shown sig...For high-repetition-rate nanosecond high-power solid-state lasers,it is essential to choose gain media with moderate saturation flux.Among these materials,Nd:Lu_(3)Al_(5)O_(12)(LuAG)transparent ceramics have shown significant potential.The thermal effect limits their power density in the gain element,but increasingthe size of the gain medium can help dissipate heat.However,a large aspect ratio can lead to high spontaneous fluorescence,causing amplified spontaneous emission(ASE)and parasitic oscillations(PO_(5)).A solution is to apply cladding layers to absorb stray radiation.Sm:LuAG transparent ceramics,with high absorption at 1064 nm,good transmittance at 808 nm,and a refractive index similar to that of Nd:LuAG,are ideal for cladding Nd:LuAG laser ceramics,In this work,highly transparent Sm:LuAG ceramics were successfully fabricated first through low-temperature vacuum pre-sintering combined with high-temperature hot isostatic pressing(HiP)post-treatment using the co-precipitated Sm:LuAG nano-powders.The influences of Sm^(3+)doping concentration on the microstructure and optical transmittance of Sm:LuAG ceramics were studied.The nano-powders calcined at 1100℃for 4 h showed dendritic agglomerations but relatively small particle sizes and high uniformity.Sm:LuAG ceramics with different doping amounts were obtained by vacuum sintering at 1550℃for 3 h followed by HIP post-treatment at 1550 C in an argon atmosphere at 200 MPa for 3 h.The 3 at%Sm:LuAG transparent ceramics(1.5 mm in thickness)exhibited the highest in-line transmittance of 83.9%at 808 nm,a fine grain size of 909 nm,and an absorption coefficient of 2.44 cm^(-1)at 1064 nm,indicating that it can effectively suppress ASE and PO.展开更多
A NASICON-type Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)cathode material was successfully synthesized using a sand grinding-spray drying method.Different doping strategies can impart distinct modifications to materials...A NASICON-type Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)cathode material was successfully synthesized using a sand grinding-spray drying method.Different doping strategies can impart distinct modifications to materials,with surface Mn-rich doping(SD)being particularly effective.On one hand,the surface enrichment layer can effectively mitigate the volumetric fluctuations of particles,thereby reducing the internal stress and enhancing the cyclic stability.More importantly,the enrichment of the Mn in the particle surface layer provides an increased number of free electrons.This elevates the local electron concentration within the material,fosters greater overlap in the wave functions of electrons,and strengthens the interactions between electrons.The higher energy state of electrons due to increased transition propensity enhances the material's electronic conductivity.As a consequence,the band gap of SD material has decreased from 0.72 eV to 0.45 eV,and the electronic conductivity has increased from 6.0μS·cm^(-1) to 21.8μS·cm^(-1).The as-optimized SD sample displays both outstanding rate performance(110.8 mAh·g^(-1) and 99.0 mAh·g^(-1) at 0.1 C and 5 C,respectively)and excellent cycling stability(88.7%of capacity retention after 1500 cycles at 1 C).The study highlights that the choice of doping methods is equally crucial for the performance of NFPP materials.展开更多
Lithium metal has a very outstanding theoretical capacity(3860 mAh/g)and is one of the most superior anode materials for high energy density batteries.However,the uncontrollable dendrite growth and the fo rmation of&q...Lithium metal has a very outstanding theoretical capacity(3860 mAh/g)and is one of the most superior anode materials for high energy density batteries.However,the uncontrollable dendrite growth and the fo rmation of"dead lithium"are the important hidden dangers of short cycle life and low safety.However,the uncontrollable dendrite growth and the fo rmation of dead lithium leads to short cycle life and hidden dange r,which hinder its practical application.Controlling the nucleation and growth process of lithium is an effective strategy to inhibit lithium dendrite.Herein,a simple in situ self-catalytic method is used to construct nitrogen doped carbon nanotube arrays on stainless steel mesh(N-CNT@SS)as a lithium composite anode.The N-doped CNTs provide a great number of N-functional groups,which enhance the lithiophilic of anode and provide a large number of uniform nucleation sites,hence it has excellent structural stability for cycles.The arrays provide neat lithium-ion transport channels to uniform lithiumion flux and inhibits dendrite generation,revealed by the COMSOL multi-physics concentration field simulation.The N-CNT@SS composite anode sustain stable at 98.9%over 300 cycles at 1 mA/cm2.NCNT@SS as the anode is coupled LiFePO_(4)(LFP)as the cathode construct a full battery,demonstrating excellent cycling stability with a capacity of 152.33 mAh/g and capacity retaining ratio of 95.4%after 100 cycles at 0.5 C.展开更多
Quantitative oxygen detection,especially at low concentrations,holds significant importance in the realms of biology,complex environments,and chemical process engineering.Due to the high sensitivity and rapid response...Quantitative oxygen detection,especially at low concentrations,holds significant importance in the realms of biology,complex environments,and chemical process engineering.Due to the high sensitivity and rapid response of the triplet excitons of phosphorescence to oxygen,pure organic room-temperature phosphorescence(RTP)materials have garnered widespread attention in recent years for oxygen detection.However,simultaneously achieving ultralong phosphorescence at room temperature and quantitative oxygen detection from pure organic host-vip doped materials poses challenges.The d ensely packed materials may decrease non-radiative decay to increase the phosphorescence,but are unsuitable for oxygen diffusion in oxygen detection.Herein,the oxygen sensitivity of host-vip doped RTP materials using 4-bromo-N,N-bis(4-(tertbutyl)phenyl)aniline(TPABuBr)as the host and 6-bromo-2-butyl-1H-benzo[de]isoquinoline-1,3(2H)-dione(NIBr)as the vip was developed.The doped material exhibits fluorescence-phosphorescence dual-emission behavior at room temperature.The tert-butyl groups in TPABuBr facilitate appropriate intermolecular spacing in the crystal state,enhancing oxygen permeability.Therefore,oxygen penetration can quench the phosphorescence emission.The observed linear relationship between the phosphorescence intensity of the doped material and the oxygen volume fraction conforms to the Stern-Volmer equation,suggesting its potential for quantitative analysis of oxygen concentration.The calculated limit of detection is 0.015%(φ),enabling the analysis of oxygen with a volume fraction of less than 2.5%(φ).Moreover,the doped materials demonstrate rapid response and excellent photostability,indicating their potential utility as oxygen sensors.This study elucidates the design and characteristics of NIBr/TPABuBr doped materials,highlighting their potential application in oxygen concentration detection and offering insights for the design of oxygen sensors.展开更多
Dye-sensitized solar cells (DSC) play a leading role in the third generation photovoltaics due to their low cost, easy fabrication process, high conversion efficiency and good stability. As a media of dye adsorption, ...Dye-sensitized solar cells (DSC) play a leading role in the third generation photovoltaics due to their low cost, easy fabrication process, high conversion efficiency and good stability. As a media of dye adsorption, electron transport, and electrolyte diffusion, the nanocrystalline semiconductor photoanode plays a key role during light-to-electricity conversion in DSC. This paper studies the influence of different ions doping and different concentration of ion doping on the electrical and optical properties of DSC, through the photoelectric property test of DSC. We learn that Zn2+ doped TiO2 photoanode is the best. At the same time there was an optimum doping concentration which was 0.05% (mole fraction).展开更多
基金National Key R&D Program of China(2023YFB3506600)。
文摘Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+),Cr^(3+)(YAGG:Ce^(3+),Cr^(3+)),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent luminescent material applications.At present,YAGG:Ce^(3+),Cr^(3+)powders exhibit good persistent performance,but their persistent performance of ceramics still needs to be further improved to meet the new requirements.In this work,(Y_(0.998)Ce_(0.002))_(3)(Al_(1-x)Cr_(x))_(2)Ga_(3)O_(12) ceramics with different Cr^(3+)doping concentrations were prepared by solid-state reaction,including air pre-sintering,hot isostatic pressing(HIP)post-treatment and air annealing,to investigate the effects of Cr^(3+)doping concentration on the microstructure,optical properties and persistent performance of the ceramics.The results showed that as the doping concentration of Cr^(3+)increased from 0.025%to 0.2%(in atom),no significant effect of Cr^(3+)concentration on the morphology of pre-sintered ceramics or HIP post-treatment ceramics was observed,but the in-line transmittance gradually increased while the persistent performance gradually decreased.Among them,YAGG:Ce^(3+),Cr^(3+)ceramics doped with 0.025%Cr^(3+)showed the strongest initial luminescence intensity exceeding 6055 mcd/m^(2) and a persistent time of 1030 min after air pre-sintering combined with HIP post-treatment and air annealing.By optimizing the Cr^(3+)doping concentration and the fabrication process,the persistent luminescence(PersL)performance of the YAGG:Ce^(3+),Cr^(3+)ceramics was obviously improved.
基金Project supported by National Natural Science Foundation of China （51074038, 51274057） and National High Technology Research and Development Program of China （2013AA030902）
文摘A solid state reaction method was used to prepare the perovskite-structured compounds BaZrl-xYxO3-a （x=0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3）. The X-ray diffraction （XRD） pattern indicated that the target perovsldte phases were obtained. With increasing Y con- centration the unit cell parameters of BaZrl-xYxO3-a samples were expanded, and Y doping became more difficult. However, high synthesis temperature is helpful to promote Y doping. The SEM results showed that the samples exhibited poor sinterability with in- creasing Y-doping content. Thermal gravimetric （TG） curves analysis showed the more mass decreasing of BaZrl-xYxO3-a （0≤x≤0.3） samples at high temperature with more Y doping and more proton introducing. The electrochemical impedance spectra （EIS） of specimens showed that conductivities of BaZrl_xYxO3（0≤x≤0.3） increased with increasing temperature from 300 to 900 ℃ in wet air. At 900 ℃, the conductivity of BaZrl-xYxO3-a （0≤x≤0.3） first increased with increasing doped amount of Y, and reached the high- est value of 1.07x 104 S/cm when x was 0.2, then decreased gradually with further increasing Y content. At 600 ℃, BaZr0.75Y0.2503-a displayed the highest conductivity, while the conductivity of BaZro.rYo.303-a was the highest at 300 ℃. The results indicated that there should be an optimum Y doping concentration yielding the highest conductivity at a constant temperature, and the optimum Y doping concentration should increase in the humidity atmosphere as the temperature decreases. So increasing the Y-doping concen- tration is helpful to improve the conductivities of BaZrl-xYxO3-a materials at low temperature.
基金supported by the National Key Research and Development Program (2016YFC0205900)the National Natural Science Foundation of China (21503106, 21567016)+1 种基金the Education Department of Jiangxi Province (KJLD14005)the Natural Science Foundation of Jiangxi Province (20142BAB213013 and 20151BBE50006)~~
文摘Catalytic oxidation of formaldehyde (HCHO) is the most efficient way to purify indoor air of HCHO pollutant. This work investigated rare earth La‐doped Pt/TiO2 for low concentration HCHO oxidation at room temperature. La‐doped Pt/TiO2 had a dramatically promoted catalytic performance for HCHO oxidation. The reasons for the La promotion effect were investigated by N2 adsorption, X‐raydiffraction, CO chemisorption, X‐ray photoelectron spectroscopy, transmission electron microscopy(TEM) and high‐angle annular dark field scanning TEM. The Pt nanoparticle size was reduced to 1.7nm from 2.2 nm after modification by La, which led to higher Pt dispersion, more exposed activesites and enhanced metal‐support interaction. Thus a superior activity for indoor low concentrationHCHO oxidation was obtained. Moreover, the La‐doped TiO2 can be wash‐coated on a cordieritemonolith so that very low amounts of Pt (0.01 wt%) can be used. The catalyst was evaluated in asimulated indoor HCHO elimination environment and displayed high purifying efficiency and stability.It can be potentially used as a commercial catalyst for indoor HCHO elimination.
基金Funded by the Guangxi Natural Science Foundation(2015GXNSFAA139253)
文摘SrTi1-yMgyO3 films were synthesized through sol-gel method on p^+-Si substrates. The effects of Mg doping concentration on the microstructure, switching behavior and properties of SrTi1-yMgyO3 films were investigated. All SrTi1-yMgyO3 films are polycrystalline, but the grain becomes coarser, and the number of holes is reduced when the Mg doping content increases from 0.04 to 0.16. SrTi1-yMgyO3 films with different Mg doping concentrations all show bipolar resistive switching behaviors but display some differences in switching properties. When y=0.08, the SrTi1-yMgyO3 films show the largest RHRS/RLRS of 105 and better fatigue endurance after 103 cycles. When y≥0.08, the distribution of Vset and Vreset is narrow, indicating good stability of writing and erasing data for a resistive random access memory. At high-resistance state, the dominant conduction mechanism of SrTi1-yMgyO3 films is the Schottky emission mechanism. However, at low-resistance state, the dominant conduction mechanisms are the filamentary conduction and changes to space charge limited current when y=0.16.
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2006AA03Z219)the Jiangsu Innovation Program for Graduate Education, China (Grant No. CXZZ11 0206)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘A novel type of n/i/i/p heterojunction solar cell with a-Si：H（15 nm）/a-Si：H（10 nm）/epitaxial c-Si（47 p.m）/epitaxial c-Si（3 um） structure is fabricated by using the layer transfer technique, and the emitter layer is deposited by hot wire chemical vapour deposition. The effect of the doping concentration of the emitter layer Sd （Sd=PH3/（PH3 ＋SiH4＋H2）） on the performance of the solar cell is studied by means of current density-voltage and external quantum efficiency. The results show that the conversion efficiency of the solar cell first increases to a maximum value and then decreases with Sd increasing from 0.1% to 0.4%. The best performance of the solar cell is obtained at Sd = 0.2% with an open circuit voltage of 534 mV, a short circuit current density of 23.35 mA/cm2, a fill factor of 63.3%, and a conversion efficiency of 7.9%.
文摘The main purpose of this work is to study doping level effects on a silicon PV cell under both moderate light concentration and normal illumination. This study also aims to compare the doping level effects under the both illumination modes. The results show for both illumination modes that diffusion parameters decrease with increasing doping level. These results are in agreement with the studies of the current and the voltage which showed for the two illumination modes that doping level increase leads to a decrease in current density and an increase in voltage. It also emerges for the two illumination modes and for the doping range 10<sup>13</sup> cm<sup>-3</sup> - 10<sup>16</sup> cm<sup>-3</sup>, a decrease of maximum power and conversion efficiency. The results also show that decrease of diffusion parameters is faster under moderate concentration in comparison with normal illumination. These results predict a greater variation rate of the current, the voltage, the maximum power and the conversion efficiency under moderate concentration compared to normal illumination. Contrary to diffusion parameters study, the results show higher variation rates of parameters under normal illumination. This is explained by the fact that under moderate concentration, carriers density is close to doping level: the cell is then in high injection condition. Consequently, under moderate concentration, carriers density is less sensitive to doping level variations. The study confirms that carriers density variation with the doping level is weak under the moderate concentration compared to normal illumination.
基金The authors acknowledge the supports from the National Natural Science Foundation of China （51172034）, and would like to thank Professor Jumu Zhu for XRD experiments.
基金supported by the National Science Fund for Distinguished Young Scholars(No.51925101)the Tencent Xplorer Prize,the National Natural Science Foundation of China(Nos.52371208,52250090,52002042,51772012,51571007and 12374023)+1 种基金Beijing Municipal Natural Science Foundation(JQ18004)the 111 Project(B17002)。
文摘Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its exceptional plasticity and promising thermoelectric performance.However,the low carrier concentration severely limits its thermoelectric performance improvement.In this work,we conducted contrasting strategies that can be employed to increase the carrier concentration of InSe,including bandgap narrowing and heterovalent doping.Specifically,the carrier concentration initially increases as a result of the reduced bandgap upon Te alloying and then slightly decreases due to the weak electronegativity of Te.Whereas Br doping realizes high carrier concentration by pushing the Fermi level into the conduction bands and activating the multiple bands.On the other hand,both Te and Br obviously suppress the thermal conductivity due to the point defect scattering.By contrast,Br doping realizes a higher thermoelectric performance with a maximum ZT of~0.13 at 773 K benefiting from the better optimization of carrier concentration.This work elucidates the strategies for enhancing carrier concentration at anion sites and demonstrates the high efficiency of halogen doping in InSe.Moreover,the carrier concentration of InSe is promising to be further optimized,and future work should focus on employing approaches such as cation doping or secondphase compositing.
文摘In this study, we investigate some main electrical parameters of the gold/poly（3-hexylthiophene）：[6,6]-phenyl C61 bu- tyric acid methyl ester：2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane/n-type silicon （Au/P3HT：PCBM：F4-TCNQ/n- Si） metal-polymer-semiconductor （MPS） Schottky barrier diode （SBD） in terms of the effects of F4-TCNQ concentration （0%, 1%, and 2%）. F4-TCNQ-doped P3HT：PCBM is fabricated to figure out the p-type doping effect on the device per- formance. The main electrical parameters, such as ideality factor （n）, barrier height （ФB0）, series resistance （Rs）, shunt resistance （Rsh）, and density of interface states （Nss） are determined from the forward and reverse bias current-voltage （l-V） characteristics in the dark and at room temperature. The values of n, Rs, ФB0, and Nss are significantly reduced by using the 1% F4-TCNQ doping in P3HT：PCBM：F4-TCNQ organic blend layer, additionally, the carrier mobility and current are increased by the soft （1%） doping. The most ideal values of electrical parameters are obtained for 1% F4-TCNQ used diode. On the other hand, the carrier mobility and current for the hard doping （2%） become far away from the ideal diode values due to the unbalanced generation of holes/electrons and doping-induced disproportion when compared with 1% F4-TCNQ doping. These results show that the electrical properties of MPS SBDs strongly depend on the F4-TCNQ doping and doping concentration of interfacial P3HT：PCBM：F4-TCNQ organic layer. Moreover, the soft F4-TCNQ dop- ing concentration （1%） in P3HT：PCBM：F4-TCNQ organic layer significantly improves the electrical characteristics of the Au/P3HT：PCBM：F4-TCNQ/n-Si （MPS） SBDs which enables the fabricating of high-quality electronic and optoelectronic devices.
文摘The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900℃and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43 .34 nm.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1601213 and 51572287)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH013)
文摘The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,the intrinsically p-type Mg3Sb2 shows low figure of merit（z T = 0.23 at 723 K） for its poor electrical conductivity.In this study,a series of Mg（3-x）LixSb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering（SPS） process.Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample,which can be essentially attributed to the increased carrier concentration,leading to a maximum z T of0.59 at 723 K with the optimum doping level x = 0.01.Additionally,the engineering z T and energy conversion efficiency are calculated to be 0.235 and 4.89%,respectively.To our best knowledge,those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.
基金supported by the National Key R&D Program of China(No.2023YFB3812000).
文摘For high-repetition-rate nanosecond high-power solid-state lasers,it is essential to choose gain media with moderate saturation flux.Among these materials,Nd:Lu_(3)Al_(5)O_(12)(LuAG)transparent ceramics have shown significant potential.The thermal effect limits their power density in the gain element,but increasingthe size of the gain medium can help dissipate heat.However,a large aspect ratio can lead to high spontaneous fluorescence,causing amplified spontaneous emission(ASE)and parasitic oscillations(PO_(5)).A solution is to apply cladding layers to absorb stray radiation.Sm:LuAG transparent ceramics,with high absorption at 1064 nm,good transmittance at 808 nm,and a refractive index similar to that of Nd:LuAG,are ideal for cladding Nd:LuAG laser ceramics,In this work,highly transparent Sm:LuAG ceramics were successfully fabricated first through low-temperature vacuum pre-sintering combined with high-temperature hot isostatic pressing(HiP)post-treatment using the co-precipitated Sm:LuAG nano-powders.The influences of Sm^(3+)doping concentration on the microstructure and optical transmittance of Sm:LuAG ceramics were studied.The nano-powders calcined at 1100℃for 4 h showed dendritic agglomerations but relatively small particle sizes and high uniformity.Sm:LuAG ceramics with different doping amounts were obtained by vacuum sintering at 1550℃for 3 h followed by HIP post-treatment at 1550 C in an argon atmosphere at 200 MPa for 3 h.The 3 at%Sm:LuAG transparent ceramics(1.5 mm in thickness)exhibited the highest in-line transmittance of 83.9%at 808 nm,a fine grain size of 909 nm,and an absorption coefficient of 2.44 cm^(-1)at 1064 nm,indicating that it can effectively suppress ASE and PO.
基金supported by the Natural Science Foundation of Shaanxi(2020JC-41)Natural Science Foundation of Shaanxi(2021TD-15)+3 种基金Scientific Research Program Funded by the Education Department of Shaanxi Provincial Governmentthe National Natural Science Foundation of China(52072298,51802261 and 22172117)the Local Special Service Program Funded by Education Department of Shaanxi Provincial Government(19JC031)the Doctoral Innovation Fund of Xi'an University of Technology(101-252072405).
文摘A NASICON-type Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)cathode material was successfully synthesized using a sand grinding-spray drying method.Different doping strategies can impart distinct modifications to materials,with surface Mn-rich doping(SD)being particularly effective.On one hand,the surface enrichment layer can effectively mitigate the volumetric fluctuations of particles,thereby reducing the internal stress and enhancing the cyclic stability.More importantly,the enrichment of the Mn in the particle surface layer provides an increased number of free electrons.This elevates the local electron concentration within the material,fosters greater overlap in the wave functions of electrons,and strengthens the interactions between electrons.The higher energy state of electrons due to increased transition propensity enhances the material's electronic conductivity.As a consequence,the band gap of SD material has decreased from 0.72 eV to 0.45 eV,and the electronic conductivity has increased from 6.0μS·cm^(-1) to 21.8μS·cm^(-1).The as-optimized SD sample displays both outstanding rate performance(110.8 mAh·g^(-1) and 99.0 mAh·g^(-1) at 0.1 C and 5 C,respectively)and excellent cycling stability(88.7%of capacity retention after 1500 cycles at 1 C).The study highlights that the choice of doping methods is equally crucial for the performance of NFPP materials.
基金supported by the National Natural Science Foundation of China(No.21646012)the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.2019DX13)+2 种基金China Postdoctoral Science Foundation(Nos.2016M600253,2017T100246)the Post-doctoralFoundation of Heilongjiang Province(No.LBH-Z16060)the Fundamental Research Funds for the Central Universities(No.HIT.NSRIF.201836)。
文摘Lithium metal has a very outstanding theoretical capacity(3860 mAh/g)and is one of the most superior anode materials for high energy density batteries.However,the uncontrollable dendrite growth and the fo rmation of"dead lithium"are the important hidden dangers of short cycle life and low safety.However,the uncontrollable dendrite growth and the fo rmation of dead lithium leads to short cycle life and hidden dange r,which hinder its practical application.Controlling the nucleation and growth process of lithium is an effective strategy to inhibit lithium dendrite.Herein,a simple in situ self-catalytic method is used to construct nitrogen doped carbon nanotube arrays on stainless steel mesh(N-CNT@SS)as a lithium composite anode.The N-doped CNTs provide a great number of N-functional groups,which enhance the lithiophilic of anode and provide a large number of uniform nucleation sites,hence it has excellent structural stability for cycles.The arrays provide neat lithium-ion transport channels to uniform lithiumion flux and inhibits dendrite generation,revealed by the COMSOL multi-physics concentration field simulation.The N-CNT@SS composite anode sustain stable at 98.9%over 300 cycles at 1 mA/cm2.NCNT@SS as the anode is coupled LiFePO_(4)(LFP)as the cathode construct a full battery,demonstrating excellent cycling stability with a capacity of 152.33 mAh/g and capacity retaining ratio of 95.4%after 100 cycles at 0.5 C.
文摘Quantitative oxygen detection,especially at low concentrations,holds significant importance in the realms of biology,complex environments,and chemical process engineering.Due to the high sensitivity and rapid response of the triplet excitons of phosphorescence to oxygen,pure organic room-temperature phosphorescence(RTP)materials have garnered widespread attention in recent years for oxygen detection.However,simultaneously achieving ultralong phosphorescence at room temperature and quantitative oxygen detection from pure organic host-vip doped materials poses challenges.The d ensely packed materials may decrease non-radiative decay to increase the phosphorescence,but are unsuitable for oxygen diffusion in oxygen detection.Herein,the oxygen sensitivity of host-vip doped RTP materials using 4-bromo-N,N-bis(4-(tertbutyl)phenyl)aniline(TPABuBr)as the host and 6-bromo-2-butyl-1H-benzo[de]isoquinoline-1,3(2H)-dione(NIBr)as the vip was developed.The doped material exhibits fluorescence-phosphorescence dual-emission behavior at room temperature.The tert-butyl groups in TPABuBr facilitate appropriate intermolecular spacing in the crystal state,enhancing oxygen permeability.Therefore,oxygen penetration can quench the phosphorescence emission.The observed linear relationship between the phosphorescence intensity of the doped material and the oxygen volume fraction conforms to the Stern-Volmer equation,suggesting its potential for quantitative analysis of oxygen concentration.The calculated limit of detection is 0.015%(φ),enabling the analysis of oxygen with a volume fraction of less than 2.5%(φ).Moreover,the doped materials demonstrate rapid response and excellent photostability,indicating their potential utility as oxygen sensors.This study elucidates the design and characteristics of NIBr/TPABuBr doped materials,highlighting their potential application in oxygen concentration detection and offering insights for the design of oxygen sensors.
文摘Dye-sensitized solar cells (DSC) play a leading role in the third generation photovoltaics due to their low cost, easy fabrication process, high conversion efficiency and good stability. As a media of dye adsorption, electron transport, and electrolyte diffusion, the nanocrystalline semiconductor photoanode plays a key role during light-to-electricity conversion in DSC. This paper studies the influence of different ions doping and different concentration of ion doping on the electrical and optical properties of DSC, through the photoelectric property test of DSC. We learn that Zn2+ doped TiO2 photoanode is the best. At the same time there was an optimum doping concentration which was 0.05% (mole fraction).
