Abstract： The effect of Al_2O_3 doping on the microstructure and electrical properties of the ZnO- Pr_6O11-CO_3O_4-MnCO_3-Y_2O_3 system was investigated in the range of 0.0-0. lmol%. The results reveal that Al_2O_3 d...Abstract： The effect of Al_2O_3 doping on the microstructure and electrical properties of the ZnO- Pr_6O11-CO_3O_4-MnCO_3-Y_2O_3 system was investigated in the range of 0.0-0. lmol%. The results reveal that Al_2O_3 doping has slight influence on the densification process. The microstructure of the ceramics comprises of ZnO phase, ZnAl_2O_4 spine phase and Pr-rich phases. The addition of Al_2O_3 greatly affects the electrical properties. The varistor voltage （E_1mA/cm^2） of ZPCMYAl samples decreases over a wide range from 5 530 V/cm to 1 844 V/cm with the increasing Al_2O_3 content. The nonlinear exponent（a） increases with the increasing Al_2O_3 content to 0.01mol%, whereas it is decreased by the further doping. The ZPCMYAI-based varistor ceramics with 0.01mol% Al_2O_3 exhibit the best electrical properties, with the nonlinear exponent （ct） attaining the highest value of 33.4 and the lowest leakage current of 2.7 μA. The capacitance-voltage （C-V） measurement shows that the donor density （Nd） at the grain boundaries increase from 1.58×10^18 to 3.15×10^18 cm^-3, the barrier height （Чb） increases from 1.60 to 2.36 eV, and the depletion layer width （t） decreases from 24.9 to 21.6 nm.展开更多
Nd2O3 doped BaTiO3ceramics（the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio）were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities thr...Nd2O3 doped BaTiO3ceramics（the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio）were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities through X-ray photoelectron spectrum （XPS）. The results showed that the dielectric characteristics of Nd2O3 doped BaTiO3 ceramics were improved by doping. When Nd2O3 content was 0.003 mol, the results were even better, the dielectric constant was increased, the dielectric loss was decreased, the Curie-temperature （Tc） was 110 ℃, and the frequency characteristic was also good. The resistivity of Nd2O3 doped BaTiO3 ceramics was lower than that of pure BaTiO3 ceramics, when Nd2O3 content was 0.001 mol,the resistivity was （2.364×）108 Ω·m, the smallest. The grain resistance of Nd2O3 doped BaTiO3 ceramics exhibited NTC effect, but the grain boundary resistance showed PTC effect, and the grain boundary resistance was larger than that of the grain resistance, so the PTC effect originated from the grain boundary. The analysis of the element binding energy through X-ray photoelectron spectrum were indicated that the quantivalence of Ba2+and Ti4+in Nd2O3 doped BaTiO3 ceramics was variable, and resulted in the improvement of the conductibility of BaTiO3 ceramics.展开更多
An improved sol-gel method was used to prepare Eu3+ ions doped SiO-Y2O3 nanocomposites. Systematic study on the effect of post-annealling treatment on photoluminescence (PL) properties of the samples under various eur...An improved sol-gel method was used to prepare Eu3+ ions doped SiO-Y2O3 nanocomposites. Systematic study on the effect of post-annealling treatment on photoluminescence (PL) properties of the samples under various europium ions doping concentrations were carried out. XRD patterns indicate that the samples show an amorphous matrix structure, and the SEM patterns show that the samples present a multi-hole loosen structure, and a rod structure after high-temperature annealling treatment (800 ℃) for 3 h. Raman spectra demonstrate that Y3+ and Eu3+ ions were incorporated into the composites successfully through the sol-gel and post-anneal process. Under the excitation of 387 nm (7F0→5G2) violet light (but not 394 nm (7F0→5L6)), the strongest emission spectrum, the red light, was observed at around 616 nm (5D0→7F2) when the samples were re-treated by annealing at high temperature after 3 months laying aside. Without annealing treatment, the optimized doping mole ratio of Eu ions is about 9%, which is much higher than that doped in SiOglass with the concentration of 3.5%, and it then becomes 5% when the samples are treated by high temperature annealing. In addition, the excitation of 532 nm (7F0→5D1) light can also arouse a comparatively strong emission.展开更多
The acid-proof anode Ti/SnO2+Mn2O3/PbO2 doped with Ce was prepared by thermal decomposition and electrodeposition combination technology, the effect of Ce on the morphology and structure of anode was also studied in t...The acid-proof anode Ti/SnO2+Mn2O3/PbO2 doped with Ce was prepared by thermal decomposition and electrodeposition combination technology, the effect of Ce on the morphology and structure of anode was also studied in this paper. The results obtained by cyclic voltammetry (CV), electrochemical impedance spectroscopic (EIS), X-ray Diffraction (XRD) and scanning electron microscopy (SEM) indicated that PbO2 crystal grains presented honeycomb structure were formed on the electrode surface by doping with Ce. The specific surface areas and catalytic active sites of the Ce-PbO2 doped electrode were increased and the catalytic activity was evidently greater than the undoped one. However, when Ce was doped into the intermediate layer (SnO2+Mn2O3), a more cracked surface structure formed, thus leading electrode deactivation by passivation of the Ti-substrate. So the anodic stability was decreased according to the accelerated life tests.展开更多
Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_...Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.展开更多
Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielect...Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielectric layer.In this paper,NH_(3)in situ doping,a process treatment approach during ALD growth of Al_(2)O_(3),is used to decrease these defects for better device characteristics.MoS_(2)FET has been well fabricated with this technique and the effect of different NH_(3)in situ doping sequences in the growth cycle has been investigated in detail.Compared with counterparts,those devices with NH_(3)in situ doping demonstrate obvious performance enhancements:Ion/Ioff is improved by one order of magnitude,from 1.33×10^(5)to 3.56×10^(6),the threshold voltage shifts from-0.74 V to-0.12 V and a small subthreshold swing of 105 m V/dec is achieved.The improved MoS_(2)FET performance is attributed to nitrogen doping by the introduction of NH_(3)during the Al_(2)O_(3)ALD growth process,which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al_(2)O_(3)layer.Furthermore,the MoS_(2)FET processed by in situ NH_(3)doping after the Al and O precursor filling cycles demonstrates the best performance;this may be because the final NH_(3)doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS_(2)channel.The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS_(2)devices.展开更多
基金Funded by the Changzhou Science and Technology Innovation Project(Nos.CC20110048 and CN20100051)
文摘Abstract： The effect of Al_2O_3 doping on the microstructure and electrical properties of the ZnO- Pr_6O11-CO_3O_4-MnCO_3-Y_2O_3 system was investigated in the range of 0.0-0. lmol%. The results reveal that Al_2O_3 doping has slight influence on the densification process. The microstructure of the ceramics comprises of ZnO phase, ZnAl_2O_4 spine phase and Pr-rich phases. The addition of Al_2O_3 greatly affects the electrical properties. The varistor voltage （E_1mA/cm^2） of ZPCMYAl samples decreases over a wide range from 5 530 V/cm to 1 844 V/cm with the increasing Al_2O_3 content. The nonlinear exponent（a） increases with the increasing Al_2O_3 content to 0.01mol%, whereas it is decreased by the further doping. The ZPCMYAI-based varistor ceramics with 0.01mol% Al_2O_3 exhibit the best electrical properties, with the nonlinear exponent （ct） attaining the highest value of 33.4 and the lowest leakage current of 2.7 μA. The capacitance-voltage （C-V） measurement shows that the donor density （Nd） at the grain boundaries increase from 1.58×10^18 to 3.15×10^18 cm^-3, the barrier height （Чb） increases from 1.60 to 2.36 eV, and the depletion layer width （t） decreases from 24.9 to 21.6 nm.
文摘Nd2O3 doped BaTiO3ceramics（the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio）were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities through X-ray photoelectron spectrum （XPS）. The results showed that the dielectric characteristics of Nd2O3 doped BaTiO3 ceramics were improved by doping. When Nd2O3 content was 0.003 mol, the results were even better, the dielectric constant was increased, the dielectric loss was decreased, the Curie-temperature （Tc） was 110 ℃, and the frequency characteristic was also good. The resistivity of Nd2O3 doped BaTiO3 ceramics was lower than that of pure BaTiO3 ceramics, when Nd2O3 content was 0.001 mol,the resistivity was （2.364×）108 Ω·m, the smallest. The grain resistance of Nd2O3 doped BaTiO3 ceramics exhibited NTC effect, but the grain boundary resistance showed PTC effect, and the grain boundary resistance was larger than that of the grain resistance, so the PTC effect originated from the grain boundary. The analysis of the element binding energy through X-ray photoelectron spectrum were indicated that the quantivalence of Ba2+and Ti4+in Nd2O3 doped BaTiO3 ceramics was variable, and resulted in the improvement of the conductibility of BaTiO3 ceramics.
基金NSFC (50272063)The Sci-Tec Project of Jiangmen City Nanocomposites (2006-10 &No .2007-11)
文摘An improved sol-gel method was used to prepare Eu3+ ions doped SiO-Y2O3 nanocomposites. Systematic study on the effect of post-annealling treatment on photoluminescence (PL) properties of the samples under various europium ions doping concentrations were carried out. XRD patterns indicate that the samples show an amorphous matrix structure, and the SEM patterns show that the samples present a multi-hole loosen structure, and a rod structure after high-temperature annealling treatment (800 ℃) for 3 h. Raman spectra demonstrate that Y3+ and Eu3+ ions were incorporated into the composites successfully through the sol-gel and post-anneal process. Under the excitation of 387 nm (7F0→5G2) violet light (but not 394 nm (7F0→5L6)), the strongest emission spectrum, the red light, was observed at around 616 nm (5D0→7F2) when the samples were re-treated by annealing at high temperature after 3 months laying aside. Without annealing treatment, the optimized doping mole ratio of Eu ions is about 9%, which is much higher than that doped in SiOglass with the concentration of 3.5%, and it then becomes 5% when the samples are treated by high temperature annealing. In addition, the excitation of 532 nm (7F0→5D1) light can also arouse a comparatively strong emission.
基金the National Natural Science Foundation of China (20476070,20771080)Natural Science Foundation of Shanxi Province (20031024 ,20041020)
文摘The acid-proof anode Ti/SnO2+Mn2O3/PbO2 doped with Ce was prepared by thermal decomposition and electrodeposition combination technology, the effect of Ce on the morphology and structure of anode was also studied in this paper. The results obtained by cyclic voltammetry (CV), electrochemical impedance spectroscopic (EIS), X-ray Diffraction (XRD) and scanning electron microscopy (SEM) indicated that PbO2 crystal grains presented honeycomb structure were formed on the electrode surface by doping with Ce. The specific surface areas and catalytic active sites of the Ce-PbO2 doped electrode were increased and the catalytic activity was evidently greater than the undoped one. However, when Ce was doped into the intermediate layer (SnO2+Mn2O3), a more cracked surface structure formed, thus leading electrode deactivation by passivation of the Ti-substrate. So the anodic stability was decreased according to the accelerated life tests.
基金supported by the Special Project for the Central Government to Guide Local Technological Development (GUIKE ZY20198008)the Guangxi Technology Base and talent Subject (GUIKE AD20238012,AD20297086)+5 种基金the Natural Science Foundation of Guangxi Province (2021GXNSFDA075012)the National Natural Science Foundation of China (51902108,52104298,22169004)the National Natural Science Foundation of China (U20A20249)the Regional Innovation and Development Joint Fundthe Guangxi Innovation Driven Development Subject (GUIKE AA19182020,19254004)the Special Fund for Guangxi Distinguished Expert。
文摘Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.
基金the National Natural Science Foundation of China(Grant Nos.61774168 and 11764008)the Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences。
文摘Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielectric layer.In this paper,NH_(3)in situ doping,a process treatment approach during ALD growth of Al_(2)O_(3),is used to decrease these defects for better device characteristics.MoS_(2)FET has been well fabricated with this technique and the effect of different NH_(3)in situ doping sequences in the growth cycle has been investigated in detail.Compared with counterparts,those devices with NH_(3)in situ doping demonstrate obvious performance enhancements:Ion/Ioff is improved by one order of magnitude,from 1.33×10^(5)to 3.56×10^(6),the threshold voltage shifts from-0.74 V to-0.12 V and a small subthreshold swing of 105 m V/dec is achieved.The improved MoS_(2)FET performance is attributed to nitrogen doping by the introduction of NH_(3)during the Al_(2)O_(3)ALD growth process,which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al_(2)O_(3)layer.Furthermore,the MoS_(2)FET processed by in situ NH_(3)doping after the Al and O precursor filling cycles demonstrates the best performance;this may be because the final NH_(3)doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS_(2)channel.The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS_(2)devices.
