稀土掺杂钇铝石榴石粉体的研究进展

钇铝石榴石(YAG)是一种理想的激光材料和高温结构材料.其作为荧光粉的应用非常广泛.本文即对稀土掺杂钇铝石榴石粉体目前的研究现状做了较系统的概述,着重介绍了钇铝石榴石的制备方法,如高温固相反应法、燃烧法、沉淀法、溶剂热法等.同时简要分析了各种方法的优缺点,指出溶剂热法能够制得分散性好、形貌较好的粉体.     

撞击流反应-沉淀法制取纳米二氧化钛

采用浸没循环撞击流反应器(SCISR),以四氯化钛水解-沉淀法制取纳米二氧化钛,得到平均粒径 9.64 nm产品,粒径分布相当窄.通过600 ℃或800 ℃下煅烧,可分别制得锐钛型或金红石型产品,后者伴随温度升高,晶粒长大,产品粒径比前者大～20 nm.     

撞击流反应——沉淀法制取纳米二氧化钛

采用浸没循环撞击流反应器（SCISR），以四氯化钛水解－沉淀法制取纳米二氧化钛，得到平均粒径9.64nm产品，粒径分布相当窄。通过600℃或800℃下煅烧，可分别制得锐钛型或金红石型产品，后者伴随温度升高，晶粒长大，产品粒径比前者大－20nm。     

YAG:Ce~(3+)玻璃陶瓷白光LED的发光特性

用化学共沉淀法制备掺铈钇铝石榴石(YAG:Ce3+)前驱体,以B2O3-Al2O3-SiO2-Na2O为玻璃基质制作Ce3+掺杂YAG玻璃陶瓷,并封装成玻璃陶瓷白光发光二极管(LED)。改变玻璃陶瓷基片厚度和外形,测量玻璃陶瓷白光LED的光电色参数,并与常规涂敷YAG荧光粉方法制作的白光LED进行对照比较。结果表明,玻璃陶瓷白光LED发射光谱波形与普通白光LED光谱基本一致。玻璃陶瓷基片从0.50mm变化到0.90mm厚时,相关色温(CCT)从4 182 K增加到8862K。0.60mm厚平板玻璃陶瓷基片封装成的白光LED荧光能量转换效率约为20%,中心CCT为6396K,-85°和+85°视角CCT分别为5921K和5898K;而平凸玻璃陶瓷基片封装成的白光LED,-85°和+85°视角CCT变化范围可控制在150K范围内。     

浸没循环撞击流反应器制备纳米氧化铝的工艺研究

在撞击流反应器中以硝酸铝和碳酸氢铵为原料、聚乙二醇(PEG)为分散剂采用均匀沉淀法制备纳米氧化铝,并用X-射线衍射仪(XRD)及透射电子显微镜(TEM)对产品进行表征.探讨了原料配比、加料时间、洗涤液体积量比、反应时间等对收率的影响,初步确定适宜的工艺条件为:碳酸氢铵和硝酸铝的摩尔比是6∶1,硝酸铝的加料时间是30 min,洗涤过程中水与乙醇的体积比为1∶1,反应时间为1 h.分析结果表明制得了平均粒径为30~40 nm的-γAl2O3产品,且收率达98.22%.     

撞击流燃煤烟气湿法脱硫吸收剂的选择

在撞击流气液反应器中对目前燃煤烟气湿法脱硫中常用的钙法(以石灰乳为吸收剂)和氨法(以氨水为吸收剂)进行了比较研究.结果表明:钙法的脱硫效率最高可达95.0%,平均87.95%;氨法的脱硫效率最高可达96.08%,平均91.30%.并以某化工厂4×300 MW燃煤机组为例,进行了技术经济分析.钙法扣除副产品销售收入后的总运行费用是7 440万元/年,氨法的相应费用为458.58万元/年,氨法脱硫优于钙法.     

撞击流燃煤烟气湿法脱硫吸收剂的选择

在撞击流气液反应器中对目前燃煤烟气湿法脱硫中常用的钙法(以石灰乳为吸收剂)和氨法(以氨水为吸收剂)进行了比较研究.结果表明:钙法的脱硫效率最高可达95.0%,平均87.95%;氨法的脱硫效率最高可达96.08%,平均91.30%.并以某化工厂4×300 MW燃煤机组为例,进行了技术经济分析.钙法扣除副产品销售收入后的总运行费用是7 440万元/年,氨法的相应费用为458.58万元/年,氨法脱硫优于钙法.     

Valence Control of Ce Ions in Cerium-substituted Yttrium Iron Garnet

Cerium-substituted yttrium iron garnet( CexY3-xFe5O12, Ce : YIG ) was prepared via coprecipitation. The structure, morphology, valence state and constituent of Ce ions were investigated respectively. X-ray powder diffraction( XRD ) analysis shows that Ce : YIG was of single cubic YIG phase. The result of X-ray photoelectron spectroscopy( XPS ) indicates the Ce ions in Ce : YIG were in the state of trivalence. Scanning electron microscope ( SEM ) demonstrates the conglobatian of Ce : YIG particles about 0.2μm scale. The magnetic properties were studied by a vibrating sample magnetometer (VSM) and the result exhibits that substitution of Ce 3 changes the magnetic parameters of YIG. The effects of doping content of Ce ions and synthesis temperature on valence control were discussed in detail.     

低温固相反应法合成钇铝石榴石粉体的研究

以分析纯六水合硝酸钇、四水合碱式乙酸铝为原料,柠檬酸为配合剂,通过碾磨发生低温固相化学反应制备前驱体,然后用煅烧的方式获得钇铝石榴石（YAG）产物。采用FTIR和TG／DSC对前驱体的组成及其热分解过程进行分析,采用XRD和SEM对产物Y3Al5O12粉末进行表征。结果表明,可在全固相条件下通过低温固相反应得到钇和铝原子级混合的前驱体,该前驱体煅烧到800℃即可形成纯净无中间产物的YAG晶体粉末,且随温度的升高,其逐渐转化为结晶良好、尺寸均匀的钇铝石榴石粉体。     

Theoretical analysis of fluid mixing time in liquid-continuous impinging streams reactor

The mixing time of impact zone in liquid-continuous impinging streams reactor(LISR) is theoretically calculated by empirical model and modern micromixing model of the fluid mixing process, and the variation laws of macromixing time and micromixing time are quantitatively discussed. The results show that under a continuous and stable operating condition, as the paddle speed increases, the macromixing time and micromixing time calculated by the two models both decrease, even in a linkage equilibrium state. Simultaneously, as the paddle speed increases, the results figured by the two models tend to be consistent. It indicates that two models both are more suitable for calculation of mixing time in high paddle speed. Compared with the existing experimental results of this type of reactor, the mixing time computed in the speed of 1500 r/min is closer to it. These conclusions can provide an important reference for systematically studying the strengthening mechanism of LISR under continuous mixing conditions.     

撞击流吸收器燃煤烟气湿法脱硫(Ⅰ)--装置设计

在分析石灰乳吸收湿法脱硫反应特性的基础上,讨论了撞击流吸收对该过程的适应性和合理性.采用旋涡压力喷嘴作为吸收剂(石灰乳)的雾化装置,对系统中主题设备的设计,包括吸收装置结构特点,工作原理,主要尺寸及其计算、决策方法进行了介绍.     

Synthesis and electrochemical properties of LiNi0.8Al0.2-xTixO2 cathode materials by an ultrasonic-assisted co-precipitation method

A new co-precipitation route was proposed to synthesize LiNi0.8Al0.2-xTixO2 (x=0.0-0.20) cathode materials for lithium ion batteries, with Ni(NO3)2, Al(NO3)3, LiOH.H2O, and TiO2 as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi0....     

Synthesis of aluminum nitride nano-powder by decomposed diethylaluminum azide in aerosols

An aerosol process for making aluminum nitride nano-powder by decomposition of single compound diethylaluminun azide was described. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to study characters of the A1N powder. It is shown that the process can produce spherical A1N powder with mean particle diameters ranging from 10 to 50 nm at 500-800℃. The generated amorphous A1N powder is characterized by a BET (Brunauer-Emmett-Teller) surface area of 103 m^2/g and is very reactive to moisture.     

燃烧法制备SrAl2O4：Eu^2＋，Dy^3＋长余辉发光材料

以硝酸盐和尿素为基质,采用一次燃烧法在较低炉温（600-620℃）下合成了SrAl2O4：Eu^2＋,Dy^3＋长余辉发光材料．通过对比实验,研究了原料的用量对产物合成及性能的影响．实验结果表明,在n（尿素）：n（硝酸盐）=12：1,硼酸摩尔分数为0．10％～0．12％,Eu2O3为0．2％,Dy2O3为0．4％时,制备的SrAl2O4：Eu^2＋,Dy^3＋具有好的余辉性能．     

Synthesis of sodium beta alumina films by heat treatment of sodium aluminum oxides

Sodium beta alumina(Na-β-alumina) films were synthesized by heat treatment of NaAl_6O_(9.5)and γ-NaA1O_2 films at temperatures of 1 373-1 573 K.Single-phase γ-NaA1O_2 and NaAl_6O_(9.5) films were prepared by laser chemical vapor deposition at the deposition temperatures of 976 and 1 100 K,respectively.Subsequent heat treatment of the films resulted in the formation of Na-β-alumina with α-Al_2O_3 at temperatures above 1 373 K for NaAl_6O_(9.5) and 1 473 K for γ-NaA1O_2.On heat treatment at temperatures of 1 473-1 573 K,the faceted morphology with terraces of the as-deposited(110)-oriented γ-NaAlO_2 films transformed to a porous morphology with platelet grains comprising Na-β-alumina and α-Al_2O_3.On heat treatment at temperatures of1 373-1 473 K,the pyramidal,faceted grains of as-deposited NaAl_6O_(9.5) films transformed to planer,shapeanisotropic morphology in the film of mixed Na-β-alumina and α-Al_2O_3.A dense morphology was observed in both the as-deposited and heat-treated NaAl_6O_(9.5) films.     

Synthesis and luminescence properties of red phosphor CaO: Eu3+

Ca(NO₃)₂·4H₂O, Eu(NO₃)₃ and H₂C₂O₄·2H₂O were adopted to synthesize CaO: Eu³⁺ with the chemical co-precipitation method, and the effects of the calcination temperature and Eu³⁺ doping concentration on the phosphor structure and its luminescent properties were investigated by TG-SDTA, XRD, and PL-PLE. The results confirm that the Eu³⁺ ions as luminescent centers substitutes Ca²⁺ sites without changing the crystal structure of cubic CaO. The optimum calcination temperature and the optimum concentration of Eu³⁺ are 1 100 ° and 1 mol%, respectively, under which the best crystallinity and highest PL intensity appeared. The maximum emission wavelength is 592 nm (⁵D₀→⁷F₁) which is excited by xenon lamp with the wavelength of 200–280 nm, indicating that the Eu³⁺ ion mainly locates in the symmetric position (O_h) in the crystal lattice of CaO. Funded by the Science and Technology Bureau of Sichun Province(No. 2006J13-059) and Education Bureau of Sichun Province (No. 2006A094)     

燃烧法制备SrAl2O4:Eu2+,Dy3+长余辉发光材料

以硝酸盐和尿素为基质,采用一次燃烧法在较低炉温(600～620℃)下合成了SrAl2O4:Eu2+,Dy3+长余辉发光材料.通过对比实验,研究了原料的用量对产物合成及性能的影响.实验结果表明,在n(尿素):n(硝酸盐)=12∶1,硼酸摩尔分数为0.10%～0.12%,Eu2O3为0.2%,Dy2O3为0.4%时,制备的SrAl2O4: Eu2+,Dy3+具有好的余辉性能.     

Preparation of YAG powder by co-precipitation method in a narrow pH-change environment

YAG(Y3Al5O12) powder was prepared by co-precipitation method.To avoid pH values changing intensely during titration process,the 4 3 NH HCO solution with 4 3 NH NO was used as precipitant solution.The pH change of precipitant solution during titration process,compositions of precursor,phase formation process and morphology of the prepared powder were investigated by means of pH meter,FT-IR,XRD and TEM.The results show that the presence of 4 3 NH NO in 4 3 NH HCO solution is crucial to alleviate the pH change,lower the calcination temperature and meliorate the morphology of YAG powder.The mechanisms were studied in detail.The YAG phase can be obtained at a lower temperature of 900 ℃.The obtained powder,composed of elliptical particles,showed a meliorated morphology.     

压力对均相共沉淀法制备羟基磷灰石晶体形貌的影响

以硝酸钙、磷酸氢二铵混合水溶液为原料、以尿素为缓冲剂,采用均相共沉淀法制备羟基磷灰石晶体,并通过X射线衍射、扫描式电子显微镜、透射电子显微镜等3种分析方法对样品分别进行了物相组成、晶体形貌、晶体取向的表征,研究了不同压力对羟基磷灰石晶体形貌的影响.结果表明:当反应压力从0.11 MPa增加至1.1 MPa时,所得羟基磷灰石晶体的物相组成由含有羟基磷灰石和磷酸八钙两种物相向只含有羟基磷灰石一种物相过渡;所得羟基磷灰石晶体的形貌从针状晶须（经由长板状和六方柱状）向薄片状晶体进行过渡;所得羟基磷灰石晶体的生长取向由沿一个方向（c轴）生长向沿另外两个方向（a轴和b轴）生长转变.     

NaOH共沉淀技术制备FeMnCuO_4复合金属氧化物

采用NaOH共沉淀法制备了尖晶石型的FeMnCuO4复合金属氧化物,并研究了不同配比以及不同煅烧温度下粉体的各项性能。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)分析了粉体的物相结构和微观形貌,并且采用紫外可见光光度计分析了在不同工艺条件下制得粉体的吸收率。结果表明,制备性能优异的FeMnCuO4复合金属氧化物的最佳工艺条件为当n(Fe3+)∶n(Cu2+)∶n(Mn2+)=1∶1∶1.5,煅烧温度为800℃。