For obtaining pure phase T12Ba2Ca2Cu3O10 （T1-2223） films with good superconducting properties, the growth technique is improved by dc magnetron sputtering and a triple post-annealing process. The triple post-anneali...For obtaining pure phase T12Ba2Ca2Cu3O10 （T1-2223） films with good superconducting properties, the growth technique is improved by dc magnetron sputtering and a triple post-annealing process. The triple post-annealing process comprises annealing twice in argon and once in oxygen at different temperatures. In the first low-temperature annealing phase in argon, T12Ba2CaCu2O8 （T1-2212） is obtained to effectively minimize evaporation in the next step. With the increase of temperature in the second annealing stage in argon, the previously prepared T1-2212 inter-phase is converted into T1-2223 phase. An additional annealing in oxygen is also adopted to improve the properties of T1-2223 films, each containing an optimal oxygen content value. The results of X-ray diffraction （XRD） θ-2θ scans, 09 scans and rotational φ scans show that each of the T1-2223 films has a high phase purity and an epitaxial structure. Smooth films are observed by scanning electron microscopy （SEM）. The critical temperatures Tc of the films are measured to be about 120 K and the critical current densities Jc can reach 4.0 MA/cm2 at 77 K at self field.展开更多
Enhancement of post-annealing stability in Co/ Ni multilayers with perpendicular magnetic anisotropy （PMA） was obtained by inserting Au layers into Ni/Co interfaces. After annealing at 350 ℃, the effective mag- net...Enhancement of post-annealing stability in Co/ Ni multilayers with perpendicular magnetic anisotropy （PMA） was obtained by inserting Au layers into Ni/Co interfaces. After annealing at 350 ℃, the effective mag- netic anisotropy density （Kef0 for Ta（3）/Pt（2）/[Co（0.3）/ Ni（0.6）/Au（0.3）]× 3/Co（0.3）/Pt（1）/Ta（3） （in nm） keeps at 0.48 × 105 J·m^-3. Scanning transmission electron micro- scopy-high-angle annular dark field （STEM-HAADF） analysis shows that the diffusion between Ni and Co layers is obstructed by the Au insertion layers among them, which is responsible for the post-annealing stability enhancement of the multilayers. Multilayers with Pt insertion layers were also investigated as reference samples in this work. Com- pared with Pt-layer-inserted Co/Ni multilayers, the Au insertion layers are found to bring seldom interfacial PMA to the multilayers, making it competitive in being employed to enhance the post-annealing stability of PMA Co/Ni multilayers which are used for magnetic random access memory devices （MRAM）.展开更多
High-performance thin-film transistors （TFTs） with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fa...High-performance thin-film transistors （TFTs） with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fabricated under the maximum process temperature of 200℃. First, we investigate the effect of post-annealing environment such as N2, H2-N2 （4%） and O2 on the device performance, revealing that o2 annealing can greatly enhance the device performance. Further, we compare the influences of annealing temperature and time on the device performance. It is found that long anneMing at 200℃is equivalent to and even outperforms short annealing at 300℃. Excellent electrical characteristics of the TFTs are demonstrated after 02 anneMing at 200℃ for 35 rain, including a low off-current of 2.3 × 10-13 A, a small sub-threshold swing of 245 m V/dec, a large on/off current ratio of 7.6×10s, and a high electron effective mobility of 22.1cm2/V.s. Under negative gate bias stress at -10 V, the above devices show better electrical stabilities than those post-annealed at 300℃. Thus the fabricated high-performance ZnO TFT with a low thermal budget is very promising for flexible electronic applications.展开更多
TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highr...TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highrate capability is limited by their poor electronic and ionic conductivity.In particular,studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported.Herein,a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported.This binder-free TNO anode exhibits superior rate performance(~66.3%capacity retention as the rate increases from 1 to 40 C),which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods,facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network.Furthermore,the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility(no capacity loss after continuous bending for 500 times).Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 mW h cm^-3/419.3 mW cm^-3),more superior to previously reported hybrid supercapacitors.The device also efficiently powers an LED light upon 180°bending.展开更多
Due to the strong magneto-elastic coupling in ferromagnetic/ferroelectric heterostructures and the potential applications in lowpower magnetoelectric nanodevices,ferroelastic domains and the corresponding dynamic evol...Due to the strong magneto-elastic coupling in ferromagnetic/ferroelectric heterostructures and the potential applications in lowpower magnetoelectric nanodevices,ferroelastic domains and the corresponding dynamic evolution under external stimuli have attracted intense research interest.Using pulsed laser deposition method,we have successfully grown layered-perovskite Bi_(2)WO_(6)thin films on SrTiO_(3)(001)substrates.Interestingly,for the as-grown thin films with step-flow morphology,the relationship between ferroelastic domain number and size shows a normal distribution,which is similar to the Boltzman distribution for confined gas molecules at equilibrium.In addition,with post-annealing,the thin films with as-grown island-like morphology can be optimized for layered morphology,and the initial small ferroelastic domains can grow into large domains.This study provides an effective strategy for ferroelastic domain engineering,which can be applied for the design of multiferroic heterostructures and low-power nanodevices.展开更多
Eu-doped Ca-α-SiAlON yellow phosphors, with the compositions Ca0.72Eu0.08Si9.56Al2.44O0.84N15.16, were prepared by a highly efficient combustion synthesis method. By optimizing the starting compositions of reactants ...Eu-doped Ca-α-SiAlON yellow phosphors, with the compositions Ca0.72Eu0.08Si9.56Al2.44O0.84N15.16, were prepared by a highly efficient combustion synthesis method. By optimizing the starting compositions of reactants and choosing appropriate post-annealing conditions, phase-pure, uniform and fine Ca-α-sialon：Eu2＋ phosphors possessing the particle size ranging -3-5μm, and good luminescence properties with an intense emission band that peaks at 592 nm under n-UV or blue light excitation were ob-tained. The results indicated that combustion synthesis method was an energy efficient, time saving and low cost way to prepare Ca-α-SiAlON phosphors by controlling the mass ratio of comburents. A combination with post-annealing treatment was desired for further increase of the properties of Ca-α-SiAlON phosphors.展开更多
A new improved two-step method in fabricating Tl_(2)Ba_(2)CaCu_(2)O_(8)(Tl-2212)thin films is presented in this paper.In the first process of dc magnetron sputtering,the thallium content in the precursor film is large...A new improved two-step method in fabricating Tl_(2)Ba_(2)CaCu_(2)O_(8)(Tl-2212)thin films is presented in this paper.In the first process of dc magnetron sputtering,the thallium content in the precursor film is largely increased by adjusting the ratio of thallium in the sputtering targets.After the second annealing process in the absence of additional thallium pellets or powder source,high-quality Tl-2212 thin films can be obtained.The proper content of thallium in the precursor film provides a relatively stable atmosphere to guarantee the growth of Tl-2212 film.This method avoids the repeated production of the thallium pellets in the post-annealing process,the repeatability and controllability of the experiment are greatly improved.X-ray diffraction(XRD)scans show that all of the sharp peaks of the sample films can be assigned to the(00 l)peaks of Tl-2212 phase.The highest superconducting critical temperature(T_(c))of the films is 105 K and the critical current density(J_(c))can achieve 1.93 MA/cm^(2) in zero magnetic field at 77 K for a 600 nm film.展开更多
Isotropic Sm-Co nanoparticle powders with high coercivity were prepared by high-energy ball milling followed by optimal annealing at different temperatures.The covercivity increased monotonically with increasing of th...Isotropic Sm-Co nanoparticle powders with high coercivity were prepared by high-energy ball milling followed by optimal annealing at different temperatures.The covercivity increased monotonically with increasing of the annealing temperature and a highest coercivity of 31.2 kOe was obtained.The sample with an optimal energy product of 17.0 MGOe still had a coercivity of 18.2 kOe.The evolution of phase,particle size,mechanism of coercivity and other related magnetic properties were analyzed.The excellent performance is attributed to nanoscale size grains below 15 nm and good exchange coupling between nanoparticles.展开更多
Rare earth(RE)-doped TiO_(2)thin films possess important applications in modern optoelectronic devices.However,the high annealing temperature requirement remains a critical restriction in device fabrications.In this w...Rare earth(RE)-doped TiO_(2)thin films possess important applications in modern optoelectronic devices.However,the high annealing temperature requirement remains a critical restriction in device fabrications.In this work,TiO_(2)thin films doped with trivalent europium(Eu^(3+))ions were fabricated by a convenient sol-gel approach and subsequent annealing treatment.Interestingly,it is found that the optimal post-annealing temperature of TiO_(2):Eu^(3+)thin film is dramatically reduced from 800 to 300℃by incorporating 10 at%Sn^(4+)into the sol precursor.The Sn-incorporated film annealed at 300℃shows a 4-fold enhancement in photoluminescence(PL)intensity related to Eu^(3+)ions to the optimized Sn-free film.Systematic analysis reveals that this enhancement is attributed to Sn element promoting the crystallization of both anatase TiO_(2)and rutile SnO_(2)clusters at 300℃,which provides sufficient SnO_(2)/TiO_(2)crystal boundary facilitating Eu^(3+)to occupy and sensitized by SnO_(2)crystals.These results provide valuable insights into fabricating highly luminescent RE-doped TiO_(2)thin films with low annealing temperature requirement,which is essential for designing optoelectronic devices based on RE materials more freely in the future.展开更多
We develop a heterojunction-based Schottky solar cell consisting of n-type GaN and PEDOT：PSS and also investigate the effect of annealing on the performance of the solar cell. The results show that the open circuit v...We develop a heterojunction-based Schottky solar cell consisting of n-type GaN and PEDOT：PSS and also investigate the effect of annealing on the performance of the solar cell. The results show that the open circuit voltage （Voc） increases from 0.54 V to 0.56 V, 0.71 V and 0.82 eV while decreases to 0.69 eV after annealing at 100 ℃, 130 ℃, 160 ℃, and 200 ℃, respectively, which can be ascribed to the change of barrier height of PEDOT：PSS/GaN Schottky contact induced by variation of the work function of the PEDOT：PSS. Furthermore, the conductivity and surface roughness measurements of the PEDOT：PSS indicate that annealing can increase the grain size and improve the connectivity between PEDOT and PSS particles, and cause thermal degradation at the same time, which leads to the rise in short-circuit current density （ISC） up to 160 ℃ and the dropoff in ISC after annealing at 200 ℃.展开更多
The rocking curve of Tl-2212 thin films in Fig.2 of our original paper[1]should be replaced with the following new one.Accordingly,in the fifth paragraph of Section 3 of the original paper,the statement“The full widt...The rocking curve of Tl-2212 thin films in Fig.2 of our original paper[1]should be replaced with the following new one.Accordingly,in the fifth paragraph of Section 3 of the original paper,the statement“The full width at half maximum(FWHM)of the(0012)peak of the Tl-2212 phase is about 0.24°”should be“The full width at half maximum(FWHM)of the(0012)peak of the Tl-2212 phase is about 0.42°”.展开更多
We have studied why PA （post-annealing） takes a long time to restore damaged crystallinity, which corresponds to repeat 10 10 times of lattice vibrations. Using a MD （molecular dynamics） simulation, we monitored t...We have studied why PA （post-annealing） takes a long time to restore damaged crystallinity, which corresponds to repeat 10 10 times of lattice vibrations. Using a MD （molecular dynamics） simulation, we monitored the time-series of the LRO （long-range order） parameter as LRO pattern, in the case of a type IIa diamond, from the beginning of ion impact by a sub-keV N2 beam implantation to a few nanoseconds, i.e., close to the feasible time limit for MD simulations. Due to the ion impact, the LRO parameter changed gradually from ＂LRO = 1＂ （crystal） to ＂LRO = 0＂ （amorphous）, showing the so-called critical slowing-down phenomenon. However, since PA was started the LRO pattern was not unique. The LRO patterns were grouped into more than three types of phases and the transition between them was also found. From the viewpoint of statistical dynamics, such chaotic variations in the LRO pattern may present that the system is a GCM （globally coupled map） of a complex system in a closed system. A GCM composed of coupled oscillators develops slowly to exhibit several different phases or ‘chaotic itinerancy＇ over time. Therefore, the long duration required for PA may be attributable to the nature of a complex system.展开更多
The effect of substrate temperature on the structure and magnetic properties of CoPt/AlN multilayer films has been investigated.The crystallinity of CoPt has been improved with increasing substrate temperature from ro...The effect of substrate temperature on the structure and magnetic properties of CoPt/AlN multilayer films has been investigated.The crystallinity of CoPt has been improved with increasing substrate temperature from room temperature to 400 ℃.After post-annealing process,L1_0 CoPt structure transformation has also been promoted.However,since the easy magnetic axis of L1_0 CoPt is in[001]orientation,the promotion of L1_0 CoPt transformation causes the change of easy magnetic axis in（111） textured CoPt layers,which impairs the perpendicular magnetic anisotropy.The optimum substrate temperature should be room temperature to obtain the strongest perpendicular magnetic anisotropy according to the results of the present work.展开更多
In this work, we studied on the boron-ions implantation, including the implant dose and post-annealing temperature on the performance of PMOS radiation field-effect transistors(RADFETs) in experimental. The possible t...In this work, we studied on the boron-ions implantation, including the implant dose and post-annealing temperature on the performance of PMOS radiation field-effect transistors(RADFETs) in experimental. The possible traps and defects induced by ions implantation in the gate-oxide and their further impacting on the sensitivity and dose range of RADFETs were analyzed qualitatively. Our devices had the dry/wet/dry sandwich gate-oxide of 420 nm thick. Different ion-implanting doses and post-annealing temperatures were carried out during the RADFETs fabrication. We built a real time auto-measurement system to realize the auto-state-switch between irradiation and read-out modes, and in-situ measurement of output voltage for ten devices in turn at once of radiation experiment. The threshold voltage, dose range and sensitivity of RADFETs were extracted and analyzed in detail. The results showed that the highest sensitivity of 229 mV/Gy achieved when the implant dose was2.2×1011 cm.2 and the post-annealing temperature was 1000°C, and the dose range of 34 Gy as well.展开更多
Ag_(3)PO_(4) as a novel photoanode material,despite its arguably highest photoactivity,suffers for its poor light absorption and stability for photoelectrochemical(PEC)water oxidation.In this work,4.54.5 cm^(2) Ag_(3)...Ag_(3)PO_(4) as a novel photoanode material,despite its arguably highest photoactivity,suffers for its poor light absorption and stability for photoelectrochemical(PEC)water oxidation.In this work,4.54.5 cm^(2) Ag_(3)PO_(4) microcrystalline films are grown via a room-temperature solution process,and vacuum annealing is proposed to solve the stability and light absorption issues.It is found that the major process below 400℃ of vacuum annealing is the|Recovery|process for Ag_(3)PO_(4) microcrystals,when lattice defects and Ag0 surface species get reduced.Next,|Recrystallization|stage occurs at>40℃.The recovery of native defects of silver vacancies,with both density functional theory calculation and experimental results,could simultaneously improve the light absorption and catalytic activity of Ag_(3)PO_(4).The 400℃-annealed Ag_(3)PO_(4) photoanode,with enhanced light harvesting and crystal quality,exhibits 88% increase in(Jlight-Jdark)value(1.94 mA cm^(-2))than non-annealed photoanode(1.03 mA cm^(-2)).Moreover,it retains>99% current density after a 4000-s stability test.These results suggest that vacuum annealing can substantially improve the PEC performance of Ag_(3)PO_(4) microcrystalline film photoanodes due to mitigated effects of native defects,improved light harvesting,and inhibited Ag_(3)PO_(4) decomposition during water oxidation reaction.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51002081 and 61176119)
文摘For obtaining pure phase T12Ba2Ca2Cu3O10 （T1-2223） films with good superconducting properties, the growth technique is improved by dc magnetron sputtering and a triple post-annealing process. The triple post-annealing process comprises annealing twice in argon and once in oxygen at different temperatures. In the first low-temperature annealing phase in argon, T12Ba2CaCu2O8 （T1-2212） is obtained to effectively minimize evaporation in the next step. With the increase of temperature in the second annealing stage in argon, the previously prepared T1-2212 inter-phase is converted into T1-2223 phase. An additional annealing in oxygen is also adopted to improve the properties of T1-2223 films, each containing an optimal oxygen content value. The results of X-ray diffraction （XRD） θ-2θ scans, 09 scans and rotational φ scans show that each of the T1-2223 films has a high phase purity and an epitaxial structure. Smooth films are observed by scanning electron microscopy （SEM）. The critical temperatures Tc of the films are measured to be about 120 K and the critical current densities Jc can reach 4.0 MA/cm2 at 77 K at self field.
基金financially supported by the National Natural Science Foundation of China(Nos.51101012, 51271211,51331002,51371025,51371027,51471028 and 51571017)the National Key Scientific Research Projects of China(No. 2015CB921502)+1 种基金the Beijing Nova Program(No.Z141103001814039)the Fundamental Research Funds for the Central Universities(No. FRF-TP-14-002C1)
文摘Enhancement of post-annealing stability in Co/ Ni multilayers with perpendicular magnetic anisotropy （PMA） was obtained by inserting Au layers into Ni/Co interfaces. After annealing at 350 ℃, the effective mag- netic anisotropy density （Kef0 for Ta（3）/Pt（2）/[Co（0.3）/ Ni（0.6）/Au（0.3）]× 3/Co（0.3）/Pt（1）/Ta（3） （in nm） keeps at 0.48 × 105 J·m^-3. Scanning transmission electron micro- scopy-high-angle annular dark field （STEM-HAADF） analysis shows that the diffusion between Ni and Co layers is obstructed by the Au insertion layers among them, which is responsible for the post-annealing stability enhancement of the multilayers. Multilayers with Pt insertion layers were also investigated as reference samples in this work. Com- pared with Pt-layer-inserted Co/Ni multilayers, the Au insertion layers are found to bring seldom interfacial PMA to the multilayers, making it competitive in being employed to enhance the post-annealing stability of PMA Co/Ni multilayers which are used for magnetic random access memory devices （MRAM）.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61474027 and 61376008
文摘High-performance thin-film transistors （TFTs） with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fabricated under the maximum process temperature of 200℃. First, we investigate the effect of post-annealing environment such as N2, H2-N2 （4%） and O2 on the device performance, revealing that o2 annealing can greatly enhance the device performance. Further, we compare the influences of annealing temperature and time on the device performance. It is found that long anneMing at 200℃is equivalent to and even outperforms short annealing at 300℃. Excellent electrical characteristics of the TFTs are demonstrated after 02 anneMing at 200℃ for 35 rain, including a low off-current of 2.3 × 10-13 A, a small sub-threshold swing of 245 m V/dec, a large on/off current ratio of 7.6×10s, and a high electron effective mobility of 22.1cm2/V.s. Under negative gate bias stress at -10 V, the above devices show better electrical stabilities than those post-annealed at 300℃. Thus the fabricated high-performance ZnO TFT with a low thermal budget is very promising for flexible electronic applications.
基金supported by the National Natural Science Foundation of China (51672205, 21673169 and 51972257)the National Key R&D Program of China (2016YFA0202602)the Natural Science Foundation of Hubei Province (2018CFB581)
文摘TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highrate capability is limited by their poor electronic and ionic conductivity.In particular,studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported.Herein,a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported.This binder-free TNO anode exhibits superior rate performance(~66.3%capacity retention as the rate increases from 1 to 40 C),which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods,facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network.Furthermore,the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility(no capacity loss after continuous bending for 500 times).Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 mW h cm^-3/419.3 mW cm^-3),more superior to previously reported hybrid supercapacitors.The device also efficiently powers an LED light upon 180°bending.
基金supported by the NSF of China(Grant No.12004036)State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(No.KFZD202201).
文摘Due to the strong magneto-elastic coupling in ferromagnetic/ferroelectric heterostructures and the potential applications in lowpower magnetoelectric nanodevices,ferroelastic domains and the corresponding dynamic evolution under external stimuli have attracted intense research interest.Using pulsed laser deposition method,we have successfully grown layered-perovskite Bi_(2)WO_(6)thin films on SrTiO_(3)(001)substrates.Interestingly,for the as-grown thin films with step-flow morphology,the relationship between ferroelastic domain number and size shows a normal distribution,which is similar to the Boltzman distribution for confined gas molecules at equilibrium.In addition,with post-annealing,the thin films with as-grown island-like morphology can be optimized for layered morphology,and the initial small ferroelastic domains can grow into large domains.This study provides an effective strategy for ferroelastic domain engineering,which can be applied for the design of multiferroic heterostructures and low-power nanodevices.
基金Project supported by the National Natural Science Foundation of China(51302311)the National High Technology Research and Development Program of China(2009AA03Z211)
文摘Eu-doped Ca-α-SiAlON yellow phosphors, with the compositions Ca0.72Eu0.08Si9.56Al2.44O0.84N15.16, were prepared by a highly efficient combustion synthesis method. By optimizing the starting compositions of reactants and choosing appropriate post-annealing conditions, phase-pure, uniform and fine Ca-α-sialon：Eu2＋ phosphors possessing the particle size ranging -3-5μm, and good luminescence properties with an intense emission band that peaks at 592 nm under n-UV or blue light excitation were ob-tained. The results indicated that combustion synthesis method was an energy efficient, time saving and low cost way to prepare Ca-α-SiAlON phosphors by controlling the mass ratio of comburents. A combination with post-annealing treatment was desired for further increase of the properties of Ca-α-SiAlON phosphors.
基金Project supported by the National Natural Science Foundation of China(Grant No.51002081)the Fundamental Research Funds for the Central Universities,Chinathe Research Program of Application Foundation and Advanced Technology of Tianjin,China(Grant No.15JCQNJC01300)
文摘A new improved two-step method in fabricating Tl_(2)Ba_(2)CaCu_(2)O_(8)(Tl-2212)thin films is presented in this paper.In the first process of dc magnetron sputtering,the thallium content in the precursor film is largely increased by adjusting the ratio of thallium in the sputtering targets.After the second annealing process in the absence of additional thallium pellets or powder source,high-quality Tl-2212 thin films can be obtained.The proper content of thallium in the precursor film provides a relatively stable atmosphere to guarantee the growth of Tl-2212 film.This method avoids the repeated production of the thallium pellets in the post-annealing process,the repeatability and controllability of the experiment are greatly improved.X-ray diffraction(XRD)scans show that all of the sharp peaks of the sample films can be assigned to the(00 l)peaks of Tl-2212 phase.The highest superconducting critical temperature(T_(c))of the films is 105 K and the critical current density(J_(c))can achieve 1.93 MA/cm^(2) in zero magnetic field at 77 K for a 600 nm film.
基金supported by the National Natural Science Foundation of China(Grant Nos.51771220,51771095,51422106)the Major Program of the Zhejiang Provincial Natural Science Foundation of China(Grant No.LD19E010001).
文摘Isotropic Sm-Co nanoparticle powders with high coercivity were prepared by high-energy ball milling followed by optimal annealing at different temperatures.The covercivity increased monotonically with increasing of the annealing temperature and a highest coercivity of 31.2 kOe was obtained.The sample with an optimal energy product of 17.0 MGOe still had a coercivity of 18.2 kOe.The evolution of phase,particle size,mechanism of coercivity and other related magnetic properties were analyzed.The excellent performance is attributed to nanoscale size grains below 15 nm and good exchange coupling between nanoparticles.
基金the National Natural Science Foundation of China(61504030,11704081)Natural Science Foundation of Guangxi Province(2020GXNSFAA238043,2020GXNSFAA297182,2017GXNSFGA198005)the Special Fund for Guangxi Distinguished Professors(Bagui Yingcai&Bagui Xuezhe)2017AD22006。
文摘Rare earth(RE)-doped TiO_(2)thin films possess important applications in modern optoelectronic devices.However,the high annealing temperature requirement remains a critical restriction in device fabrications.In this work,TiO_(2)thin films doped with trivalent europium(Eu^(3+))ions were fabricated by a convenient sol-gel approach and subsequent annealing treatment.Interestingly,it is found that the optimal post-annealing temperature of TiO_(2):Eu^(3+)thin film is dramatically reduced from 800 to 300℃by incorporating 10 at%Sn^(4+)into the sol precursor.The Sn-incorporated film annealed at 300℃shows a 4-fold enhancement in photoluminescence(PL)intensity related to Eu^(3+)ions to the optimized Sn-free film.Systematic analysis reveals that this enhancement is attributed to Sn element promoting the crystallization of both anatase TiO_(2)and rutile SnO_(2)clusters at 300℃,which provides sufficient SnO_(2)/TiO_(2)crystal boundary facilitating Eu^(3+)to occupy and sensitized by SnO_(2)crystals.These results provide valuable insights into fabricating highly luminescent RE-doped TiO_(2)thin films with low annealing temperature requirement,which is essential for designing optoelectronic devices based on RE materials more freely in the future.
基金supported by the Fundamental Research Funds for the Central Universities of Ministry of Education of China(Grant No.JB141104)
文摘We develop a heterojunction-based Schottky solar cell consisting of n-type GaN and PEDOT：PSS and also investigate the effect of annealing on the performance of the solar cell. The results show that the open circuit voltage （Voc） increases from 0.54 V to 0.56 V, 0.71 V and 0.82 eV while decreases to 0.69 eV after annealing at 100 ℃, 130 ℃, 160 ℃, and 200 ℃, respectively, which can be ascribed to the change of barrier height of PEDOT：PSS/GaN Schottky contact induced by variation of the work function of the PEDOT：PSS. Furthermore, the conductivity and surface roughness measurements of the PEDOT：PSS indicate that annealing can increase the grain size and improve the connectivity between PEDOT and PSS particles, and cause thermal degradation at the same time, which leads to the rise in short-circuit current density （ISC） up to 160 ℃ and the dropoff in ISC after annealing at 200 ℃.
文摘The rocking curve of Tl-2212 thin films in Fig.2 of our original paper[1]should be replaced with the following new one.Accordingly,in the fifth paragraph of Section 3 of the original paper,the statement“The full width at half maximum(FWHM)of the(0012)peak of the Tl-2212 phase is about 0.24°”should be“The full width at half maximum(FWHM)of the(0012)peak of the Tl-2212 phase is about 0.42°”.
文摘We have studied why PA （post-annealing） takes a long time to restore damaged crystallinity, which corresponds to repeat 10 10 times of lattice vibrations. Using a MD （molecular dynamics） simulation, we monitored the time-series of the LRO （long-range order） parameter as LRO pattern, in the case of a type IIa diamond, from the beginning of ion impact by a sub-keV N2 beam implantation to a few nanoseconds, i.e., close to the feasible time limit for MD simulations. Due to the ion impact, the LRO parameter changed gradually from ＂LRO = 1＂ （crystal） to ＂LRO = 0＂ （amorphous）, showing the so-called critical slowing-down phenomenon. However, since PA was started the LRO pattern was not unique. The LRO patterns were grouped into more than three types of phases and the transition between them was also found. From the viewpoint of statistical dynamics, such chaotic variations in the LRO pattern may present that the system is a GCM （globally coupled map） of a complex system in a closed system. A GCM composed of coupled oscillators develops slowly to exhibit several different phases or ‘chaotic itinerancy＇ over time. Therefore, the long duration required for PA may be attributable to the nature of a complex system.
文摘The effect of substrate temperature on the structure and magnetic properties of CoPt/AlN multilayer films has been investigated.The crystallinity of CoPt has been improved with increasing substrate temperature from room temperature to 400 ℃.After post-annealing process,L1_0 CoPt structure transformation has also been promoted.However,since the easy magnetic axis of L1_0 CoPt is in[001]orientation,the promotion of L1_0 CoPt transformation causes the change of easy magnetic axis in（111） textured CoPt layers,which impairs the perpendicular magnetic anisotropy.The optimum substrate temperature should be room temperature to obtain the strongest perpendicular magnetic anisotropy according to the results of the present work.
基金supported by the National Basic Research Program of China(Grant No.2015CB352100)
文摘In this work, we studied on the boron-ions implantation, including the implant dose and post-annealing temperature on the performance of PMOS radiation field-effect transistors(RADFETs) in experimental. The possible traps and defects induced by ions implantation in the gate-oxide and their further impacting on the sensitivity and dose range of RADFETs were analyzed qualitatively. Our devices had the dry/wet/dry sandwich gate-oxide of 420 nm thick. Different ion-implanting doses and post-annealing temperatures were carried out during the RADFETs fabrication. We built a real time auto-measurement system to realize the auto-state-switch between irradiation and read-out modes, and in-situ measurement of output voltage for ten devices in turn at once of radiation experiment. The threshold voltage, dose range and sensitivity of RADFETs were extracted and analyzed in detail. The results showed that the highest sensitivity of 229 mV/Gy achieved when the implant dose was2.2×1011 cm.2 and the post-annealing temperature was 1000°C, and the dose range of 34 Gy as well.
基金This work was supported by Fundamental Research Funds for the Central Universities of Ministry of Education of China(Southeast University)Core-to-Core Program(Advanced Research Networks Type A)of Japan Society for the Promotion of Science(JSPS)+4 种基金Q.Cao acknowledges the support of China Scholarship Council(No.201506100018)the START project of Japan Science and Technology Agency(JST)R.Che thanks the support of National Basic Research Program(973 Program No.2018YFA0209102)National Science Fund for Distinguished Young Scholars(No.51725101)National Natural Science Foundation of China(Nos.11727807,51672050,and 61790581)of China.
文摘Ag_(3)PO_(4) as a novel photoanode material,despite its arguably highest photoactivity,suffers for its poor light absorption and stability for photoelectrochemical(PEC)water oxidation.In this work,4.54.5 cm^(2) Ag_(3)PO_(4) microcrystalline films are grown via a room-temperature solution process,and vacuum annealing is proposed to solve the stability and light absorption issues.It is found that the major process below 400℃ of vacuum annealing is the|Recovery|process for Ag_(3)PO_(4) microcrystals,when lattice defects and Ag0 surface species get reduced.Next,|Recrystallization|stage occurs at>40℃.The recovery of native defects of silver vacancies,with both density functional theory calculation and experimental results,could simultaneously improve the light absorption and catalytic activity of Ag_(3)PO_(4).The 400℃-annealed Ag_(3)PO_(4) photoanode,with enhanced light harvesting and crystal quality,exhibits 88% increase in(Jlight-Jdark)value(1.94 mA cm^(-2))than non-annealed photoanode(1.03 mA cm^(-2)).Moreover,it retains>99% current density after a 4000-s stability test.These results suggest that vacuum annealing can substantially improve the PEC performance of Ag_(3)PO_(4) microcrystalline film photoanodes due to mitigated effects of native defects,improved light harvesting,and inhibited Ag_(3)PO_(4) decomposition during water oxidation reaction.
