Morphology controllable synthesis of yttrium oxide-based phosphors from yttrium citrate precursors

A novel yttrium citrate-templated conversion method for morphology controlled synthesis of Y2O3 microspheres, microflowers and microsheets was reported for the first time. The precursors with controllable morphologies were synthesized with a homogenous precipitation method in aqueous solution without any surfactant. Y2O3 samples with well-preserved morphological architectures were obtained by a subse-quent thermal transformation strategy. The chemical formula of the precursor was identified and a two-stage ...     

撞击流-活性炭吸附法制备氧化钇超细粉体

以Y( NO3)3·6H2O和碳酸氢铵为原料,在撞击流反应器中制备碳酸钇,经焙烧得到超细氧化钇粉体.考察了分散剂加入量、反应物摩尔比n( NH4HCO3)/n(Y(NO3)3)、活性碳用量、反应温度、反应时间、搅拌速度以及碳酸钇的焙烧温度和焙烧时间等因素对Y2O3粒径的影响,并用WJL激光粒度仪、TG、XRD和SEM等表征手段对产品进行表征,从而获得制备超细氧化钇的优化工艺条件为:PEG4000的质量为硝酸钇的3％,活性炭用量为0.025 mol·L-1,反应物摩尔比n( NH4HCO3):n(Y( NO3)3)为8:1,反应温度50℃,反应40 min,螺旋桨转速1000 r·min-1,800℃下焙烧1.5h,在此条件下制得球形氧化钇超细粉体,表观粒径小于0.5μm.     

Synthesis and characterization of BaCeO3 nanocrystals via solvothermal-based method

A facile approach to preparing well-dispersed nanocrystals of BaCeO3 was developed by a combination of solvothermal and annealing processes. The precursor consisted of amorphous BaCO3 and CeO2, and the conversion of the precursor to crystalline BafeO3 nanocrystals occurred upon heat treatment at a relatively low temperature. The as-processed BaCeO3 had an orthorhombic structure and the average size of such crystals was approximately 80 nm. The obtained products were characterized by Fourier Transform Infrared （FT-IR）, X-Ray Diffraction （XRD）, Laser Raman Spectroscopy （LRS）, Scanning Electron Microscopy （SEM）, Energy Dispersive X-Ray Spectrometry （EDS）, and Transmission Electron Microscopy （TEM）. This preparation process could also be used to synthesize doped barium cerate complex oxides Bafe0.95M0.05O3-δ （M=Y, Nd, Gd, and Sm）.     

Synthesis and characterization of Y_2O_2S:Eu~(3+),Mg~(2+),Ti~(4+) nanorods via a solvothermal routine

Y2O2S:Eu3+,Mg2+,Ti4+ nanorods were prepared by a solvothermal procedure.Rod-like Y(OH)3 was firstly synthesized by hydrothermal method to serve as the precursor.Y2O2S:Eu3+,Mg2+,Ti4+ powders were obtained by calcinating the precursor at CS2 atmosphere.The Y2O2S:Eu3+,Mg2+,Ti4+ phosphor with diameters of 30-50 nm and lengths up to 200-400 nm inherited the rod-like shape from the precursor after calcined at CS2 atmosphere.The Y2O2S:Eu3+,Mg2+,Ti4+ nanorods showed hexagonal pure phase,good dispersion and exhibite...     

Research on cathode material of Li-ion battery by yttrium doping

Modification of LiFePO4, LiMn2O4 and Li1 xV3O8 by doping yttrium was investigated. The influences of doping Y on structure, morphology and electrochemical performance of cathode materials were investigated systematically. The results indicated that the mechanisms of Y doping in three cathode materials were different, so the influences on the material performance were different. The crystal structure of the three materials was not changed by Y doping. However, the crystal parameters were influenced. The crystal parameters of LiMn2O4 became smaller, and the interlayer distance of (100) crystal plane of Li1 xV3O8 was lengthened after Y doping. The grain size of Y-doped LiFePO4 became smaller and grain morphology became more regular than that of undoped LiFePO4. It indicated that Y doping had no influence on crystal particle and morphology of LiMn2O4. The morphology of Li1 xV3O8 became irregular and its size became larger with the increase of Y. For LiFePO4 and Li1 xV3O8, both the initial discharge capacities and the cyclic performance were improved by Y doping. For LiMn2O4, the cyclic performance became better and the initial discharge capacities declined with increasing Y doping.     

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.     

Effect of Sulfate Ions on YAG Powders Synthesized by Microwave Homogeneous Precipitation

Using Al(NO3)3·9H2O, NH4Al(SO4)2·12H2O, Y(NO3)3 as mother salts, and urea as precipitant, YAG nano-powders were synthesized by microwave homogeneous precipitation. The composition, morphology, and phase transformation of precursor were analyzed by IR, XRD and TEM. The size distribution of YAG powders was characterized using laser diffraction method. The results show that sulfate ions influence the dispersion, composition and morphology of the YAG precursors. The addition of moderate sulfate ions can produce YAG powders with nano size and excellent dispersion at 1100 ℃.     

Nanostructured yttrium aluminum garnet powders synthesized by co-precipitation method using tetraethylenepentamine

Tetraethylenepentamine(C8H23N5,TEPA) has been used as a novel precipitant to synthesize yttrium aluminum garnet(Y3Al5O12,YAG) precursor from a mixed solution of aluminum and yttrium nitrates via a normal-strike co-precipitation method without controlling the pH value during precipitation process.The original precursor was analyzed by thermogravimetry/differential scanning calorimetry(TG/DSC).The evolution of phase composition and micro-structure of the as-synthesized YAG powders were characterized by X-ray ...     

Study on phosphating treatment of aluminum alloy： role of yttrium oxide

Zinc phosphate coatings formed on 6061-Al alloy, after dipping in phosphating solutions containing different amounts of Y2O3(yttrium oxide), were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical measurements. Significant variations in the morphology and corrosion resistance afforded by zinc phosphate coating were especially observed as Y2O3 in phosphating solution varied from 0 to 40 mg/L. The addition of Y2O3 changed the initial potential of the interface between aluminum alloy substrate and phosphating solution and increased the number of nucleation sites. The phosphate coating thereby was less porous structure and covered the surface of aluminum alloy completely within short phosphating time. Phosphate coating was mainly composed of Zn3(PO4)2-4H2O (hopeite) and AIPO4(aluminum phosphate). Y2O3, as an additive of phosphatization, accelerated precipitation and refined the gain size of phosphate coating. The corrosion resistance of zinc phosphate coating in 3% NaCl solution was improved as shown by po-larization measurement. In the present research, the optimal amount of Y2O3 was 10-20 mg/L, and the optimal phosphating time was 600 s.     

微波外场对液相合成砂状氧化钇前驱体形貌的影响

在微波外场作用下,以YCl3溶液为原料、草酸为沉淀剂直接液相合成了大颗粒砂状Y2O3前驱体,采用SEM、XRD和TG-DTA对前驱体及热分解产物进行表征,考察了H2C2O4与YCl3的摩尔比、YCl3起始浓度、反应时间和反应温度等对前驱体形貌的影响.结果表明,在微波外场作用及H2C2O4与YCl3的摩尔比为2∶1、YCl3的起始浓度为0.5 mol/L、反应时间3 h和反应温度40℃液相合成条件下,可得到D50约为40μm的附聚形大颗粒砂状前驱体.     

Rare earth application for heat-resisting alloys

High-temperature oxidation resistance of Al2O3-and Cr2O3-forming heat-resisting alloys with rare earths(yttrium-implanted FeCrAl,-added FeCrAl,-added FeCrAlPt alloys,Y2O3-or CeO2-coated NiCrSi,yttrium-or lutetium-added NiCr and NiCrSi) was studied in oxygen at high temperatures,by mass gain measurements,mass change measurements,amount of spalled oxide,observation of surface appearance,X-ray diffraction(XRD),scanning electron microscopy(SEM),electron probe X-ray microanalysis(EPMA) and transmission electron microscopy(TEM).After oxidation at 1573 K for 18 ks in oxygen,oxide scale on FeCrAl alloy spalled from the entire surface,however,yttrium-implanted FeCrAl alloys showed good oxide adherence.After oxidation at 1473 K for 18 ks in oxygen,mass gain of FeCrAlY alloys decreased with increasing yttrium of up to 0.1 wt.% follwed by an increase with the yttrium content,and the mass gain of FeCrAl0.005Pt0.05Y alloy with appropriate additions of platinum and yttrium was lower than that of FeCrAl0.1Y alloy.Yttrium-added FeCrAl alloys showed good oxide adherence.TEM analysis revealed that the alumina/alloy interface of FeCrAl0.005Pt0.05Y alloy showed good coherency.The scale surface of FeCrAl alloy was rough,however,those of FeCrAlY and FeCrAlPtY alloys were smooth.Cyclic oxidation of NiCrSi,Y2O3-or CeO2-coated NiCrSi alloys was studied up to 10 cycles(1 cycle:300 s) at 1523 K in oxygen.Mass change of NiCrSi alloy increased up to 3 cycles and then decreased up to 10 cycles because of oxide spallation during cooling.On the other hand,mass change of Y2O3-or CeO2-coated NiCrSi alloy increased up to 10 cycles,and these alloys showed good oxide adherence.Granular Cr2O3 particles on Y2O3-coated NiCrSi alloy were in size smaller than these on CeO2-coated NiCrSi alloy.This result suggested that oxidation rate of Y2O3-coated NiCrSi alloy was lower than that of CeO2-coated NiCrSi alloy.After oxidation at 1473 and 1573 K for 18 ks in oxygen,mass gain of yttrium-or lutetium-added NiCr and NiCrSi alloys decreased.Oxide scales on NiCrS     

Synthesis and characterization of branched yttrium hydroxide fluoride microcrystals with hierarchical tubular structure

Hexagonal yttrium hydroxide fluoride microcrystals were prepared by a two-step hydrothermal route using yttrium nitrate, sodium hydroxide and sodium fluoride as raw materials to react in propanetriol solvent. The samples were characterized by powder X-ray diffraction (XRD), energy dispersive spectrum (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier trans-form infrared spectroscopy (FT-IR), thermogravimetre and differential-thermogravimetric analysis (TG-DTA), which revealed that Y(OH)2.14F0.86 microcrystals were multi-branched and that the branches of Y(OH)2.14F0.86 microcrystals were composed of hierarchical tubes. This novel multi-branched and intriguing hierarchical tubular structure of yttrium hydroxide fluoride maybe has a potential application in photoelectric crystals. The formation of branched Y(OH)2.14F0.86 microcrystals with hierarchical tubular structure were due to the substitution reaction and Oswald ripening.     

Uniform YF_3 nanorods:Synthesis,luminescent properties and cytotoxicity study

Uniform YF3 nanorods composed of nanoparticles were successfully prepared via a facile solvothermal method with ethanol as solvent and tetrabutyl ammonium fluoride(TBAF) as fluorine source.The products were characterized with powder X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The nanorods were with diameters of ca.60 nm and lengths ranging from 200 to 350 nm.Eu3+ and Tb3+ doped YF3 nanorods were also prepared and their photoluminescence properties were ...     

Strengthening and Toughening Effect of Yttrium on Al2O3/TiCN Ceramic Tool Material

Modern ceramic cutting tool materials with their excellent physical, mechanical properties and cutting performances promote greatly the development of metal cutting technology.Therefore, they are one of the most promising cutting tool materials in the coming Zlst century["'l. however, the intrinsic brittleness is a fatal weakness for ceramic tool materials. In order to reduce the brittleness and to increase the strength and the fracture toughness of the cutting tool materials, various research…     

Preparing of Nano-Sized Power RE2O3(RE = La,Y,Gd) by Pyrolying Precursors

The precursors RE (HSal) 3 ( RE = La, Y, Gd; HSal = C6 H4 (OH) COO) were synthesized by the rheological phase reaction method. The mechanism and products of thermal decomposition of precursors was studied by using TG,DTA, gas chromatography-mass spectrometry (GC-MS). Nano-sized RE2O3 ( RE = La, Y and Gd) power were obtained by thermal decomposition of the precursors in air at 800 ℃. TEM measurement indicates that RE2O3 are spherical particles. The middle level diameter ( d50 ) of the particles are 19.3 ( La2O3 ) , 53.8 ( Y2O3 ) and 28.6 nm( Gd2O3 ) respectively by means of laser particles size analyzer.     

Spectroscopic properties of Gd2Oa：Dy3＋ nanocrystals

Gd2O3:Dy3+ nanocrystals were synthesized via solvothermal method followed by a subsequent calcination.The samples were characterized by X-ray diffraction(XRD),transmission electron microsopy(TEM),Electronic dispersive X-ray spectroscopy(EDX),photoluminescence(PL)spectrum and decay curves.The effect of the annealing temperature on the crystallinity and particle size was studied;heat treatment improved the crystallinity of as-prepared nanocrystals as well as increased their particle size.The nanocryatals presented monodispersed spherical shape under TEM.Photoluminescence spectra showed that nanocrystal exhibited strong yellow emission corresponding to 4F9/2→6H13/2 transition(573 nm)of Dy3+ under UV light excitation,which broadened with the particle size decreased without structure changed.The theoretical mechanism of luminescence was explored and surface effect was thought to be the main reason.     

（Y，Eu）2O3红生粉的粒度和形貌控制研究

以草酸共沉淀法制备（Y,Eu）2O3为红生粉,对比六种沉淀方式对红生粉形貌的影响,其中在沉淀过程中添加氨水并用双加料的方式可制备出形貌上优于红生粉商品,其粒度分布呈正态分布;通过调节草酸过量系数、沉淀过程中添加氨水的量、合成温度及草酸浓度等沉淀条件可控制红生粉D50的变化。     

Preparation of Neodymium-Doped Yttrium Aluminum Garnet Transparent Ceramics by Homogeneous Precipitation Method

Neodymium-doped yttriumaluminumgarnet(Nd∶YAG)transparent polycrystalline ceramics,laser ce-ramic matrix materials,are gradually becomingsubsti-tutes for single crystals because they are provided withpredominantly chemical stability,highly doped ionconcentration,excellent optical performance and hightemperature stability[1,2].Presently,the conventionallyused methods to produce Nd∶YAG powders are solid-state processes[3],chemical precipitation methods[4,5]andlowtemperature combustiontechniqu…     

Microstructural characteristics and second-phase particles in yttrium-bearing Fe-10Ni-7Mn martensitic steels

In this study, the microstructure and second-phase particles in yttrium （0.05 wt.%and 0.8 wt.%） bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy indicated the formation of （Fe, Ni, Mn）17Y2 precipitates with hexagonal structure in a Fe-10Ni-7Mn-0.8Y （wt.%） alloy. Lattice parameters of these precipitates were calculated as follows：a=0.8485 nm and c=0.8274 nm. Formation of Y2O3 sub-micron particles was also confirmed in both yttrium bearing steels via electrolytic phase extraction method. The effect of these precipitates on the prior austenite grain size was investigated. The results revealed that these precipitates had an effective role in controlling the prior austenite grain size.     

Low-temperature electrochemical synthesis and characterization of ultrafine Y（OH）_3 and Y_2O_3 nanoparticles

Ultrafine Y(OH)3 nanoparticles were successfully deposited from an additive-free 0.005 mol/L YCl3 low-temperature bath on the steel cathode at the current density of 0.5 mA/cm2 and bath temperature of 10 oC. Heat treatment of the prepared Y(OH)3 nanoparticles at 600 oC in air led to the formation of Y2O3 nanoparticles. Thermal behavior and phase transformation during the heat treatment of Y(OH)3 were investigated by differential scanning calorimetry (DSC) and thermogramimetric analysis (TGA). The morphologies, crystal structures and compositions of the prepared materials were examined by means of scanning and transmission electron microscopy (SEM and TEM) as well as X-ray diffraction (XRD) and FT-IR spectroscopy. The results showed that the prepared Y(OH)3 nanoparticles was essentially amorphous and composed of well dispersed ultrafine particles with size of 4 nm. After heat treatment, the obtained oxide product was well crystallized cubic phase of Y2O3 nanoparticles with the grain size of around 5 nm. It was concluded that low-temperature cathodic electrodeposition offered a facile and feasible way for preparation of ultrafine Y(OH)3 and Y2O3 nanoparticles.