The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic ...The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic process. The experimental results show that the rare earth doping can increase the aspect axial ratio of needle α-FeOOH grains. its anti-sintering capability during the heat-treatment and the thermostability of γ-Fe2O3 magnetic properties. The magnetic properties of γ-Fe2O3 doping with rare earth are as follows: the coercivity Hc=36.3 kA/m (445 Oe), the ratio saturation magnetization σs=90.4μWbm/kg (72 emu/g), the ratio remanent magnetization σr=54 μWbm/kg (43 emu/g), and the temperature coefficient of remanent magnetization of γ-Fe2O3 doping with 0.1 mol% Dy can reach -5 ×10-4℃-1.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
Mg PSZ ceramics doped with Y 2O 3 and CeO 2 was prepared using traditional processing method. The fine grain PSZ ceramics( d c10 μm) sintered at low temperature(1550 ℃) was obtained by means of composition ...Mg PSZ ceramics doped with Y 2O 3 and CeO 2 was prepared using traditional processing method. The fine grain PSZ ceramics( d c10 μm) sintered at low temperature(1550 ℃) was obtained by means of composition design. The effects of co stabilization of Y 2O 3, CeO 2 and annealing at 1100 ℃ on material composition, microstructure and mechanical properties were studied. The results show that Y 2O 3 and CeO 2 during annealing at 1100 ℃ can inhibit subeutectoid decomposition reaction effectively, and optimize nucleation and growth of t ZrO 2 precipitates in c ZrO 2 matrix phase. The materials show transgranular and intergranular fracture characteristics, and exhibit better mechanical properties owing to the cooperative effect of stress induced transformation toughening and microcrack toughening.展开更多
The transport properties were studied for rare earth manganese oxide La_(0.67)Ca_(0.33)Mn_(1-x)Fe_xO_3 (x=0～0.3) systems. It is found that with increasing Fe^(3+)-doping content x, the resistance increases and the in...The transport properties were studied for rare earth manganese oxide La_(0.67)Ca_(0.33)Mn_(1-x)Fe_xO_3 (x=0～0.3) systems. It is found that with increasing Fe^(3+)-doping content x, the resistance increases and the insulator-metal transition temperature (T_(IM)) shifts to lower temperature. If the doping content is small, the transport properties manifest metallic characteristics in the temperature range of T<T_(IM), while they will obey a thermal activation model in the temperature range of T>T_(IM). Such a behavior may be attributed to the Fe^(3+)-doping and possible Mn ions scattering to electrons. The Fe^(3+) doping may lead to the formation of Fe^(3+)-O^(2-)-Mn^(4+) channels, which could terminate the double exchange Mn^(3+)-O^(2-)-Mn^(4+) channels. The antiferromagnetic clusters of Fe ions may induce the Mn ions to scetter to the electrons.展开更多
Various affecting factors and degradation mechanism were studied on ultrasonic degradation of methyl orange adopting Y2O3 doping anatase TiO2 catalyst prepared in laboratory.In the experiment, the UV-VIS spectrophotom...Various affecting factors and degradation mechanism were studied on ultrasonic degradation of methyl orange adopting Y2O3 doping anatase TiO2 catalyst prepared in laboratory.In the experiment, the UV-VIS spectrophotometer was used to follow and inspect the degradation process of methyl orange.The results indicate that the ultrasonic degradation ratios of methyl orange in the presence of anatase TiO2 catalyst are much better than those without catalyst.Moreover, the catalytic performance of Y2O3 doping anatase TiO2 catalyst is obviously higher than that of anatase TiO2 catalyst without doping.The optimal conditions were adopted in this work and the degradation and COD elimination ratio of methyl orange got to98% and 99.0% in 90 min, respectively.展开更多
In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as...In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.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
Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good cry...Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good crystal structure, Y^3＋ doping makes the lattice parameter and crystal volume small. Cyclic vohammogram testing result shows that a small quantity of Y^3＋ doping has no influence on the Li^＋ deinsertion-insertion process, but Y^3＋ doping decreases the interacting force among Li^＋ , and then availably avoids the energy level splitting. The electrochemical property testing indicates that the initial discharge ca- pacity at x =0.02 is 117.2 mAh·g^-1 and remains 96.9% with 113.6 mAhg^-1 after 20 cycles, which explains that Y^3＋ doping effectively restricts Jahn-Teller effect and stabilizes the crystal structure. AC analysis shows that conductivity of the samples is clearly improved due to Y^3＋ doping.展开更多
文摘The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic process. The experimental results show that the rare earth doping can increase the aspect axial ratio of needle α-FeOOH grains. its anti-sintering capability during the heat-treatment and the thermostability of γ-Fe2O3 magnetic properties. The magnetic properties of γ-Fe2O3 doping with rare earth are as follows: the coercivity Hc=36.3 kA/m (445 Oe), the ratio saturation magnetization σs=90.4μWbm/kg (72 emu/g), the ratio remanent magnetization σr=54 μWbm/kg (43 emu/g), and the temperature coefficient of remanent magnetization of γ-Fe2O3 doping with 0.1 mol% Dy can reach -5 ×10-4℃-1.
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.
文摘Mg PSZ ceramics doped with Y 2O 3 and CeO 2 was prepared using traditional processing method. The fine grain PSZ ceramics( d c10 μm) sintered at low temperature(1550 ℃) was obtained by means of composition design. The effects of co stabilization of Y 2O 3, CeO 2 and annealing at 1100 ℃ on material composition, microstructure and mechanical properties were studied. The results show that Y 2O 3 and CeO 2 during annealing at 1100 ℃ can inhibit subeutectoid decomposition reaction effectively, and optimize nucleation and growth of t ZrO 2 precipitates in c ZrO 2 matrix phase. The materials show transgranular and intergranular fracture characteristics, and exhibit better mechanical properties owing to the cooperative effect of stress induced transformation toughening and microcrack toughening.
文摘The transport properties were studied for rare earth manganese oxide La_(0.67)Ca_(0.33)Mn_(1-x)Fe_xO_3 (x=0～0.3) systems. It is found that with increasing Fe^(3+)-doping content x, the resistance increases and the insulator-metal transition temperature (T_(IM)) shifts to lower temperature. If the doping content is small, the transport properties manifest metallic characteristics in the temperature range of T<T_(IM), while they will obey a thermal activation model in the temperature range of T>T_(IM). Such a behavior may be attributed to the Fe^(3+)-doping and possible Mn ions scattering to electrons. The Fe^(3+) doping may lead to the formation of Fe^(3+)-O^(2-)-Mn^(4+) channels, which could terminate the double exchange Mn^(3+)-O^(2-)-Mn^(4+) channels. The antiferromagnetic clusters of Fe ions may induce the Mn ions to scetter to the electrons.
基金Project supported by the National Natural Science Foundation of China(20371023 )
文摘Various affecting factors and degradation mechanism were studied on ultrasonic degradation of methyl orange adopting Y2O3 doping anatase TiO2 catalyst prepared in laboratory.In the experiment, the UV-VIS spectrophotometer was used to follow and inspect the degradation process of methyl orange.The results indicate that the ultrasonic degradation ratios of methyl orange in the presence of anatase TiO2 catalyst are much better than those without catalyst.Moreover, the catalytic performance of Y2O3 doping anatase TiO2 catalyst is obviously higher than that of anatase TiO2 catalyst without doping.The optimal conditions were adopted in this work and the degradation and COD elimination ratio of methyl orange got to98% and 99.0% in 90 min, respectively.
基金supported by the National Natural Science Foundation of China (52202001)Open Project of Advanced Laser Technology Laboratory of Anhui Province (AHL2021KF07)+1 种基金Major Science and Technology of Anhui Province(202203a05020002)University Natural Science Research Project of Anhui Province (KJ2021A0388)。
文摘In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.
文摘采用高温固相反应法制备了Sr_(1-x)Ca_xSi_2O_2N_2∶Eu^(2+)系列荧光粉,研究Y^(3+)离子掺入对荧光粉发光性能的影响。对于Sr Si_2O_2N_2∶Eu^(2+),Y^(3+)离子掺入主要起到稳定Eu^(2+)价态的作用,避免Eu^(2+)氧化为Eu^(3+),从而提高Sr Si_2O_2N_2∶Eu^(2+)的发光性能。对于Ca Sr Si_2O_2N_2∶Eu^(2+),Y^(3+)离子掺入除了稳定Eu^(2+)价态作用外,还能有效减小Eu^(2+)取代Ca^(2+)后晶格膨胀引起的应力,提高Eu^(2+)在晶格中的溶解度。Sr_(1-x)Ca_xSi_2O_2N_2∶Eu^(2+)(x=0,0.15,0.3,0.6,0.75,0.95)系列荧光粉中随着Ca含量的增加,共掺Y^(3+)离子对样品发光强度的提高程度也随之增加(20%~80%)。
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.
文摘Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good crystal structure, Y^3＋ doping makes the lattice parameter and crystal volume small. Cyclic vohammogram testing result shows that a small quantity of Y^3＋ doping has no influence on the Li^＋ deinsertion-insertion process, but Y^3＋ doping decreases the interacting force among Li^＋ , and then availably avoids the energy level splitting. The electrochemical property testing indicates that the initial discharge ca- pacity at x =0.02 is 117.2 mAh·g^-1 and remains 96.9% with 113.6 mAhg^-1 after 20 cycles, which explains that Y^3＋ doping effectively restricts Jahn-Teller effect and stabilizes the crystal structure. AC analysis shows that conductivity of the samples is clearly improved due to Y^3＋ doping.
