Hydrothermal Preparation and Luminescence of LaF3：Eu^3＋ Nanoparticle

Pure andEu^3＋-doped LaF3 nanoparticle were prepared by a hydrothermal process at a low temperature and characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and fluorescence spectra. Well-dispersed nanopartiele with an average size of 30 nm and a hexagonal shape were synthesized. The effects of temperature and reaction time on the preparation of nanoparticle were investigated, and the growth mechanism of nanoparticle was briefly discussed. The effects of Eu^3＋-doped concentration, the calcination time and temperature were also investigated. An optimal Eu^3 ＋-doped concentration of 5% is found. Calcination temperature and prolonged of the nanoparticle at high time greatly reduce the fluorescence intensity. The sample calcinated at 600 ℃ for 6 h emits the strongest fluorescence.     

Preparation and Characterization of Sol-Gel Derived Au Nanoparticle Dispersed Y2O3：Eu Films

Gold nanoparticles dispersed Y2O3 films were prepared through a sol-gel method by using yttrium acetate and Au nanoparticles colloid as precursors. The films were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and UV-VIS absorption spectra. XRD patterns and TEM images of Y2O3 ＋ Au films give the same resuits on structure and particle size as that of pure Y2O3 films. The surface plasma resonance （SPR） of Au nanoparticles in Y2O3 ＋ Au film was observed around 550 nm in the absorption spectrum and its position shifts to red with increasing annealing temperature is caused by the increase of dielectric constant of Y2O3 matrix and the size of Au nanoparticles. The second and third order nonlinear optical effects of Y2O3 ＋ Au films were also observed. The photoluminescent properties of Y2O3 ： Eu ＋ Au films were investigated and results indicate that there exist an energy transfer from Eu^3 ＋ to Au nanoparticles and this energy transfer decreases the emission of Eu^3 ＋ in Y2O3 ： Eu ＋ Au film.     

Effects of La^3＋ Non-Uniformly Doping in TiO2 Films on Photocatalytic Activities

TiO2 thin films non-uniformly doped by La^3＋ were prepared by sol-gel method. The comparison of thin film activities, which was characterized by photocatalytic degradation of methyl orange, shows that doping modes have great activities. The non-uniformly effects on photocatalytic doped TiO2 films resuh in good photocatalytic activities with an optimal concentration; about 0. 5% （ atom fraction ）. UV-Vis transmittance spectra indicate that the absorption edges of these TiO2 thin films shift to ward longer wave- lengths remarkably, and electrochemical behavior also reveales that e^- -h^＋ pairs are prone to formation and separation under UV irradiation. The mechanism of photocatalytic activities are enhanced by La^3＋ non-uniformly doping was discussed on the analogy of the theory of “window effect” of solar cell heterojunction.     

Synthesis and Characterization of Cerium-Doped Lutetium Aluminum Garnet Phosphors by Nitrate-citrate Sol-Gel Combustion Process

Nanosized cerium-doped lutetium aluminum garnet （LuAG：Ce） phosphors were prepared by nitrate-citrate solgel combustion process using 1：1 ratio of the citrate：nitrate. The prepared LuAG：Ce phosphors were characterized by XRD, TEM, photoluminescence and radioluminescence spectra excited by UV and X-ray, respectively. The purified crystalline phase of LuAG：Ce was obtained at 900 ℃ by directly crystallizing from amorphous materials. The resultant Lu- AG：Ce phosphors were uniform and had good dispersivity with an average particle size of about 30 urn. Both photoluminescence and radioluminescence were well-known Ce^3＋ emissions located in the range of 470 -600 nm consisting of two emission bands because of the transition from the lowest 5d excited state （2D） to the 4f ground state of Ce^3＋, which matched well with the sensitivity curve of the Si-photodiode. There was a little red shift for the emission components from the UV-excited emission spectrum to the X-ray-excited emission spectrum. The fast scintillation decay component of 26 ns satisfies the requirements of fast scintillators.     

Luminescent properties of amorphous phosphor 1.4YeO3·2.5Al2O3·0.1Tb2O3 prepared by sol-gel method

Amorphous phosphor 1.4YeO3·2.5Al2O3·0.1Tb2O3 （the same composition as Y2.8Tb0.2Al5O12） was prepared via a sol-gel method at relatively low temperature （i.e., below 650℃）, which is much lower than that for the preparation of polycrystalline Y3Al5O12：Tb^3＋ （above 1400℃）. The amorphous phosphor prepared in the optimized conditions showed a bright green-yellowish luminescence, the intensity of which was comparable with that of polycrystalline sample and the emissions of which were assigned to 5D4 → 7Fj transitions of Tb^3＋. Besides the emissions of Tb^3＋, the amorphous samples prepared at temperatures below 500 ℃ presented a weak blue emission band around 420 nm.     

Photoluminescence Characteristics of Gd2Mo3O9 ： Eu Phosphor Particles by Solid State Reaction Method

Eu^3＋-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with space group I41/α. The effects of flux content and sintering temperature on the luminescent properties were investigated with the emission and excitation spectra. The results showed that flux content and sintering temperature had effects on the luminescent properties, the optimized flux content and the best temperature was 3 % and 800 ℃ respectively. The excitation and emission spectra also showed that this phosphor could be effectively excited by C-T band （280 nm）, ultraviolet light 395 nm and blue light 465 nm. The wavelengths at 395 and 465 nm were nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Gd2Mo3O9 ： Eu was twice higher than that of Y2O2S ： Eu^3 ＋ under 395 nm excitation. The Eu^3＋ doped Gd2Mo309 phosphor may be a better candidate in solid-state lighting applications.     

Magnetic properties of SmCo-based permanent magnetic films during 25 to 300 ℃

Magnetic properties of the SmCo-based permanent magnetic films prepared on hot substrate with Mo and Cr underlayer without subsequent annealing process were investigated by vibrating sample magnetometer （VSM）, X-ray diffraction （XRD）, and en- ergy dispersive X-ray spectroscopy （EDS）. The results showed that the film thickness of the SmCo-based films presented complex effect on the intrinsic coercivity Hci. Optimal Hc~ for the films with Mo underlayer, Cr underlayer, and without underlayer was ob- served with different film thicknesses. Furthermore, the monotonous temperature dependence of Hci was found to be strongly corre- lated with the magnetic parameters for the 3.0 μm thick SmCo7 films with Mo underlayer. From 25 to 300 ℃, the Hci decreased from 281.6 to 211.2 kA/m with a temperature coefficient of-0.091%/℃, exhibiting good temperature stability.     

Preparation and photoluminescence of Tb^3＋ doped SrAl2O4 phosphor by composite combustion method

High-efficient Tb^3＋ activated SrAl2O4 phosphor was synthesized by a combined combustion-solid-state reaction method. The precursor of SrAl2O4：Th^3＋ phosphor was prepared via a combustion process, and then the as-prepared powder was heated in a reductive ambient of activated carbon at 1250 ℃ for 1 h. The results of X-ray diffraction, scanning electron microscopy, and photoluminescence spectra revealed the influence of the dosage of urea and heated process on the crystallinity, morphology, and photoluminescence of the phosphor. Comparing with traditional solid-sate reaction, the crystallinity and emission intensity of the SrAl2O4：Tb^3＋ phosphor were improved by this two-step process.     

Sol-gel preparation of La-doped bismuth ferrite thin film and its low-temperature ferromagnetic and ferroelectric properties

Bi0.85La0.15FeO3 thin film was prepared on ATO glass substrates by sol-gel technique. The effect of La doping on phase structure, film surface quality, ion valence, and ferroelectric/magnetic properties of Bi0.85La0.15FeO3 film were investigated. La dop-ing suppressed the formation of impurity phases and the transition of Fe3+ to Fe2+ ions at room temperature. Compared with the un-doped BiFeO3, La-doping also increased the average grain size and the film density, which resulted in the decrease of film leakage current density. The remanent polarization and saturation magnetization were enhanced significantly by La doping. The remanent polarization of Bi0.85La0.15FeO3 films gradually decreased while saturation magnetization increased with the decrease of measuring temperature within a range from 50 to 300 K.     

Influence of Magnetic Annealing on Properties of SmFe Thin Films

SmFe thin films were prepared by DC magietron sputtering at room temperature and 300 %. The influence of magnetic annealing temperature on the phase structure and magnetic properties was investigated. Results showed that thermal sputtering followed by a heat treatment process helped to obtain a structure with a relatively large fraction of SmFe2. Residual phases observed were α-Fe, Sm2O3, and unknown phases. During the annealing treatment, the intrinsic compressive stress in SmFe films was relieved and could become tensile at higher annealing temperatures. The degree of in-plane anisotropy weakened, and furthermore, the anisotropy transformed into out-of-plane anisotropy.     

Synthesis and luminescent properties of Pr-doped Lu3Al5O12 translucent ceramic

Lutetium aluminum garnet (LuAG) precursors doped with different Pr3+ concentration (0.25at.%, 0.5at.%, 1.0at.%, 3.0at.%, 5.0at.%) were synthesized via a co-precipitation method using ammonium hydrogen carbonate as precipitant. The phase evolution and mor-phology of the precursor were characterized with X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The resultant LuAG:Pr3+ powder was sintered into translucent ceramic without any additives in vacuum at 1150℃ and then in nitrogen atmosphere at 1700℃. Photohiminescence spectra of LuAG:Pr3+ powder and ceramic were measured at room temperature in vacuum ultraviolet (VUV) and ultraviolet (VU) region. For the 5d-4f transition of Pr3+ ions, dominant emission of ceramic samples peaking round 311 nm had higher lumines-cence intensity. And the host absorption in ceramic samples was not as intensive as that in powder samples. The luminescent intensity of LuAG:Pr3+ varied with the Pr3+ contents and the quenching concentration was about 1.0at.% for ceramic and 3.0at.% for powder, which was much higher than 0.24at.% for LuAG:Pr3+ single crystals. This phenomenon showed that the ceramic had some superiority over single crystals.     

Luminescent properties of β-Lu2Si2O7:RE3+(RE=Ce, Tb) nanoparticles by sol-gel method

Nanoscale RE3 (RE=Ce, Tb) doped and codoped lutetium pyrosilicate Lu2Si2O7 (LPS) phosphors were prepared by using the sol-gel method. Heat treatment was performed in the temperature range from 900 to 1100℃. The crystal structure was analyzed by X-ray diffraction (XRD). The results showed that the β-type structure of LPS was obtained at 1100℃. The excitation spectra in the UV and VUV ranges and the emission spectra of the samples were measured at room temperature, and their luminescent properties were studied. The energy transfer from Ce3 to Tb3 in the codoped samples were observed and discussed.     

Synthesis and luminescent properties of Ce~(3+) doped LuAG nano-sized powders by mixed solvo-thermal method

Polycrystalline LuAG:Ce3+(cerium3+-doped lutetium aluminum garnet) powders were prepared by mixed solvo-thermal method.Fourier-transform IR spectroscopy(FTIR) and X-ray diffraction(XRD) measurements showed that the precursors were ethanol derivatives AlO(OH) crystal with hydroxyl and carbonate group.XRD results showed that phase of Lu2O3 disappeared with the precursors were annealed at 400 °C,cubic phase LuAG:Ce3+ appeared but only one diffraction peaks of LuAP(LuAlO3) at calcination temperature to 700 °C,and the purified crystalline phase of LuAG:Ce3+ was obtained at 1000 °C.The scanning electron microscopy(SEM) analysis revealed that the synthesized LuAG:Ce3+ powders were uniform and had good dispersivity with an average particle size about 100 nm.Excitation and emission spectra of Ce3+ doped LuAG phosphors were measured.Many factors of affecting the intensity of emission spectra were discussed.     

Tb3+掺杂复合材料LaF3-SiO2的制备和发光性能研究

采用溶胶-凝胶法在室温条件下制备了掺杂Tb3+的复合材料LaF3 -SiO2,通过XRD、TG-DTA、IR、激发和发射光谱研究了材料的结构和发光性能.结构表测试表明,在高于494℃时LaF3-SiO2:Tb3+转变为稳定的氟铈矿六方结构,800℃退火处理后,材料主要存在Si-O-Si键;发光性能研究表明,最佳退火温度为800℃;样品在544nm监测波长下,最佳激发波长为228nm,Tb3+的最佳掺杂摩尔浓度为0.48％.     

熔盐法制备(La,Ce,Tb) PO4的工艺研究(

以NaCl和KCl为熔盐,采用熔盐法合成了(La,Ce,Tb)PO₄绿色荧光粉.利用XRD、SEM、激光粒度仪、光谱分析仪等测试和分析荧光粉物相、粒径、形貌及发光性能,主要考察了复合熔盐用量、合成时间及合成温度对荧光粉性能的影响,并对反应机理进行探讨.结果表明,复合熔盐与前驱体的摩尔比为2.5~3.5,在900 ℃保温3 h,可以得到性能良好的(La,Ce,Tb) PO₄绿色荧光粉,其发光亮度优于高温固相法.      

Research on Performance of ZnS∶TbF_3 Thin Film Electroluminescence Device

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Hydrothermal synthesis,structure study and luminescent properties of YbPO₄:Tb³⁺ nanoparticles

YbPO4:Tb3+ were synthesized by mild hydrothermal method.The luminescent properties,morphologies and structure of the obtained powders were characterized by photoluminescence(PL) spectra,FESEM,X-ray diffractometer(XRD) and FTIR.The results showed that the prepared YbPO4:Tb3+ nanoparticles were pure tetragonal phase and the average grain size varied with increasing of Tb3+ concentration.Hydrothermal temperature was revealed to be the key factor to enhance the emission intensity of YbPO4:Tb3+ phosphors.The spherical nanoparticles could be effectively excited by near UV(369 nm) light and exhibited green performance at 543 nm(5D4→7F5),489 nm(5D4→7F6) and 586 nm(5D4→7F4).The CIE chromaticity was calculated to be x=0.298,y=0.560.The YbPO4:Tb3+ nanoparticles exhibited potential to act as UV absorber for solar cells to enhance the conversion efficiency.     

Surface and Texture Properties of Tb-Doped Ceria-Zirconia Solid Solution Prepared by Sol-Gel Method

The three-way catalysts （TWCs） promoters Ce0.6Zr0.4- x TbxO2-y were prepared by sol-gel method. BET surface areas analysis indicated that an increase of the dopant Tb content from x = 0.05 to x = 0.15 favors an increase of surface area from 66.8 to 80.4 m^2· g^-1 compared with the undoped sample Ce0 .6oZr0.40O2 65.1 m^2·g^- 1 after calcination at 650℃. Transmission electron microscopy （TEM） observation indicated that the doped samples have a higher thermal stability. The XRD and Raman spectra confirmed that the Ce0.6Zr0.4-xTbxO2-y cubic solid solution is formed. XPS analysis revealed that Ce and Tb mainly existed in the form of Ce^4＋ and Tb^3 ＋ , and Zr existed in the form of Zr^4＋ on the surface of the samples. The doped samples were homogenous in composition ; the introduction of Tb into the CeO2-ZrO2 promoters resuited in the formation of a solid solution, and the concentration of surface lattice oxygen was increased.     

高温氧化协同原位掺硼提升金刚石薄膜的亲水性

用H₂、CH₄和B₂H₆气体作为气源,采用热丝化学气相沉积技术在单晶硅衬底上分别制备纯金刚石膜和含硼金刚石薄膜,然后在600~800℃高温氧化。通过扫描电镜、拉曼光谱及X射线衍射仪对金刚石膜层的形貌和成分进行表征,用常温接触角测试仪对其亲水性进行表征,研究高温氧化协同原位掺硼对金刚石薄膜亲水性的影响。结果表明,随高温氧化温度升高,膜层逐渐被刻蚀至出现微孔形貌,其中纯金刚石膜层在700℃下氧化后,接触角从68.1°降低至21.5°,膜层亲水性提高。随掺硼浓度提高,微孔逐渐消失,在V(H2):V(CH₄):V(B₂H₆)=97:3:0.4条件下制备的掺硼金刚石膜,并在800℃氧化处理后,具有最小接触角14.1°。在原位掺硼和高温氧化的协同作用下,膜层成分发生改变,同时金刚石完美构型出现缺陷,微孔形貌使金刚石膜层的表面能增大,从而有效提高金刚石薄膜的亲水性。