Formation Mechanism of the Slice and Rod-Like Cerium Dioxide Precursor Particles

2013 ◽  
Vol 743-744 ◽  
pp. 389-396 ◽  
Author(s):  
Jian Qing Chen ◽  
Zhi Gang Chen ◽  
Yong Wei
Keyword(s):  
Cerium Dioxide ◽  
Ageing Time ◽  
Transition Process ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Nitrate Hexahydrate ◽  
X Ray Diffraction ◽  
Method Effects ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

Ultra-fine cerium dioxide precursor particles was prepared with cerium (III) nitrate hexahydrate (Ce (NO3)36H2O) and urea (CO(NH2)2) at 85°C by homogenous precipitation method. Effects of reaction and ageing time on the morphology of the precursor particles were studied, the morphology of precursor particles was characterized by scan electronic microscope and the crystallinity of the precursors was studied by X-ray diffraction. The result showed that the mono-dispersed spherical particles turned into flower and bundle-like particles as reaction time increasing, the particles turned into slice and rod-like particles as the ageing time increasing, the transition process occurred in ageing process was later than that in the reaction process, the spherical particles were less crystallization and the slice and the rod-like particles were at a state of fine crystallization.

Synthesis of Nanosized Pseudoboehmite and γ-Al2O3 by Control Precipitation Method

2013 ◽  
Vol 684 ◽  
pp. 46-52 ◽  
Author(s):  
Zhou Qing Jiang ◽  
Hong Wen Ma ◽  
Jing Yang ◽  
Le Wang
Keyword(s):  
Aqueous Solution ◽  
Diffraction Analysis ◽  
Sodium Sulfate ◽  
Ageing Time ◽  
Precipitation Method ◽  
Al2o3 Nanoparticles ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray

Nanosized pseudoboehmite particles were synthesized by the precipitation of sodium sulfate and ammonia in aqueous solution at 70°C. After calcinations, the pseudoboehmite could successfully transfer to γ-Al2O3 nanoparticles while retaining their previous morphology. The influence of the reaction conditions on formation of pseudoboehmite and γ-Al2O3 had been researched in detail. The X-ray diffraction analysis showed that nanosized crystalline pseudoboehmite was formed at pH 8-8.5 after ageing 2 hours. Utilization of surfactant(PEG1000) would produce finer nanoparticles with well-dispersion. With the ageing time or the surfactant amount increasing, the morphology of the resulting particles transformed from spherical to fibrous

Effect of Surfactant on the Preparation of Nano-powder for Yb Doping Laser Transparent YAG Ceramic

2013 ◽  
Vol 32 (5) ◽  
pp. 511-515 ◽  
Author(s):  
Xiao Guo Cao ◽  
Jia Wang ◽  
Qi Bai Wu ◽  
Hai Yan Zhang
Keyword(s):  
Particle Size ◽  
Polyethylene Glycol ◽  
Average Particle Size ◽  
Ammonium Bicarbonate ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Nano Powder ◽  
Co Precipitation

AbstractYb:YAG transparent ceramic nano-powder was prepared by chemical co-precipitation method, with ammonium bicarbonate as the precipitant and polyethylene glycol as surfactant. The addition of polyethylene glycol can reduce the agglomeration and particle size of the prepared Yb:YAG powder. The morphology, thermal stability and phase structure of Yb:YAG nano-powder were charactered by scanning electron microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. The results show that well-crystallized nano-powder was obtained by calcining the precursors at 900 °C for 3 h. The average particle size of Yb:YAG powder is about 100–200 nm. When the volume amount of polyethylene glycol is 2.0%, well-dispersed Yb:YAG powder with spherical particles of 100 nm diameter was obtained.

The Morphology of Si-K-HAs Composite Prepared by Spray Drying

2019 ◽  
Vol 966 ◽  
pp. 19-24
Author(s):  
Srie Muljani ◽  
Heru Setyawan ◽  
Ketut Sumada
Keyword(s):  
Surface Area ◽  
Spray Drying ◽  
Humic Substance ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Infrared Spectrometry ◽  
Drying Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spray Dried

The silica potassium humic substance (Si-K-HAs) composite have been produce by spray drying successfully. In the previous study the preparation of Si-K-HAs gel by precipitation method required the addition of acid so that Si-K-HAs gel product contains acid salts. This study was develope spray drying method in order to eliminate the use of acid. The mixture of potassium silicate, cellulose and humic potassium solution was mixed with varying volume ratios and flowed into a spray dryer to produce Si-K-HAs powder. The used of cellulose (CMC) in this study acts as a homogeneous agent so that silica and humic substance can be completely mixed at controlled viscosity. Si-K-HAs products were characterized by Scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), and Surface area analytical (SAA). The result showed that the Si-K-HAs composite prepared by spray dryers have spherical particles, SiO2 in the range of 48-50%, K2O in the range of 49-50%. The present of cellulose caused the increasing of Si-K-HAs particle size e.g 17.30 μm prepared without CMC to 41.11 μm prepared with addition of 100g of CMC. The presence of cellulose can also increase the surface area of the spray-dried Si-K-HAs particles from 111.92 m2g-1; 163.241 m2g-1.

Green synthesis of ZnS nanoparticles and fabrication of ZnS–chitosan nanocomposites for the removal of Cr(vi) ion from wastewater

2021 ◽  
Vol 10 (1) ◽  
pp. 374-383
Author(s):  
Thokozani Xaba
Keyword(s):  
Metal Ion ◽  
Hexagonal Phase ◽  
Optical Measurements ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Cubic Phase ◽  
Average Crystalline Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Zns Nanoparticles

Abstract A modified homogeneous precipitation method has been used to synthesize ZnS nanoparticles. Starch and polyvinyl alcohol (PVA) were utilized as capping molecules, and later, the ZnS–PVA-capped nanoparticles were then incorporated with chitosan to form ZnS–chitosan nanocomposites for the removal of Cr(vi) ion from wastewater. The optical measurements of the synthesized ZnS nanoparticles showed the band gap which was blue-shifted when compared with the bulk ZnS material. The crystalline structures were determined by X-ray diffraction, and the crystalline sizes were estimated from the Scherer formula. XRD spectra confirmed the formation of hexagonal phase for the uncapped ZnS nanoparticles with an average crystalline size of 3.71 nm whereas the starch- and PVA-capped ZnS nanoparticles showed the formation of cubic phase structures with crystalline sizes of 3.26 and 2.88 nm. The TEM image showed spherical particles with regular morphologies and significantly narrow size distributions. The calculated average particle diameters were in good agreement with the estimated XRD result. The removal of Cr(vi) ion from wastewater was studied through the adsorption process. The effect of pH, dosage, and contact time was investigated. More than 95% of the metal ion recovery was achieved through using ZnS–chitosan nanocomposites.

Microstructure and Mechanical Properties of (CrTiNb)N Films

2014 ◽  
Vol 915-916 ◽  
pp. 808-811
Author(s):  
Yu Feng ◽  
Jun Zhang
Keyword(s):  
Mechanical Properties ◽  
Bias Voltage ◽  
High Speed ◽  
High Speed Steel ◽  
Fracture Morphology ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Friction Resistance ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

(CrTiNb)N hard reactive films are prepared by multi-arc ion plating technology using the combination of Ti-Nb alloy target and Cr target. The high speed steel (HSS) is adopted as substrate. The surface and cross-fracture morphology, the surface compositions and the phase structures of the as-deposited (CrTiNb)N films are observed and measured by scan electronic microscope (SEM) and X-ray diffraction (XRD). The mechanical properties including the micro-hardness, the adhesion between film and substrate, the friction and wear resistance of the as-deposited (CrTiNb)N films are systemically investigated. The effects of deposition bias voltage and the addition of Nb element on the as-deposited (CrTiNb)N films are discussed. It is revealed that the optimally comprehensive performances including the micro-hardness, the adhesion and also the friction resistance can be achieved by the (CrTiNb)N hard reactive films with bias voltage of 200V.

Microstructure analysis of carbon–carbon preform

2004 ◽  
Vol 19 (7) ◽  
pp. 2124-2130 ◽  
Author(s):  
Zhenyi Liu ◽  
Guoding Zhang ◽  
Jinliang Sun ◽  
Hong Li ◽  
Musu Ren
Keyword(s):  
Crystal Structure ◽  
Pyrolytic Carbon ◽  
Processing Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Preform ◽  
Anisotropic Form ◽  
Degree Of Graphitization ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

The microstructure of three kinds of porous carbon–carbon preforms prepared for carbon–carbon/aluminum composites was identified by x-ray diffraction, Raman spectroscopy, and field emission scan electronic microscope. Although manufactured at same processing conditions, including the temperature, type of organic gas, and pressure of pyrolysis, the structure of the pyrolytic carbon (Cpy) in three kinds of preforms is different. The morphology of the Cpy is influence by the topology of the preforms greatly, and the crystal structure of the Cpy is influenced by the crystal structure of the carbon fiber greatly, on which surface the Cpy was deposited. The degree of graphitization of the Cpy had been enhanced and the structure of the Cpy changed to more anisotropic form when the preforms were annealed at 2773 K.

Research on the Al3+，V5+ Double Ionic Substitute Negative Thermal Expansion Compound Zr1-xAlxMoW1-yVyO8

2011 ◽  
Vol 689 ◽  
pp. 407-412
Author(s):  
Shao Hua Shen ◽  
Xian Zhi Qin ◽  
Shao Bin Xiang ◽  
Fu Heng Hao ◽  
Jing Tan ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Potential Applications ◽  
Conductive Property ◽  
Co Precipitation ◽  
Electronic Microscope

The ZrW2O8 family of materials has been shown to display the unusual property of an isotropic bulk contraction in volume with the rising of temperature. They have a number of potential applications, for example, they would be widely used in composite material and solid electrolyte based on its characteristic of negative thermal expansion and ionic conductive property. In this paper, an Al3+，V5+ double substitute negative thermal expansion (NTE) solid solution Zr1-xAlxMoW1-yVyO8 was synthesized by co-precipitation method. The phase composition, the micromorphology and the thermal expansion coefficient were obtained by using X-ray diffraction (XRD), scanning electronic microscope (SEM) and thermal mechanical analyzer (TMA), respectively. The results show that the sample’s density rises with the increasing of the content of V5+, while, its porosity declines. The thermal expansion coefficients of the samples are between -3.0~4.0×10-6 K-1, it indicates that their negative thermal expansion behavior is a little lower than that of ZrMoWO8. And the experiment also shows that these samples have displayed a fine behavior of heat shock resistance.

Fabrication, Properties and Laser Performance of Indium-Substituted YAG:Ho Phosphor by Co-Precipitation Method

2013 ◽  
Vol 320 ◽  
pp. 40-43 ◽  
Author(s):  
Shi Xing Liu ◽  
Wei Zhang ◽  
Zheng Fa Hu ◽  
Hao Yi Wu ◽  
Xia Sheng
Keyword(s):  
Photoluminescence Property ◽  
Critical Distance ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Garnet Phase ◽  
Yttrium Aluminum ◽  
Method Effects ◽  
Co Precipitation ◽  
Scanning Electron

Ho-doped Yttrium aluminum indium garnet, Y3Al4.5In0.5O12 (YAIG), was synthesized by co-precipitation method. Effects of Ho concentration, reaction mechanism, crystallinity and luminescence properties of the phosphor powders were studied using the X-ray diffraction, thermo-gravimetry Analyzer,scanning electron microscopy and photoluminescence. The performances of samples were analyzed by changing the concentration of Ho3+ and the substitution of indium for aluminum. The results showed that pure cubic garnet phase was formed in the Indium-substituted samples, and the critical distance of the energy transfer was 1.41 nm. Both the excitation and emission intensities increased firstly and then decreased with the increasing of Ho3+ concentration. When the concentration of Ho3+ reached 15%, the photoluminescence property of the sample was best.

Synthesis of Si-O-C Nanoballs by CVD of Polydimethylsiloxane

2012 ◽  
Vol 454 ◽  
pp. 114-117
Author(s):  
Xia Yuan ◽  
Yu Liang An ◽  
Hong Chao Sui ◽  
Chen Zhang
Keyword(s):  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cvd Method ◽  
Silicon Carbon ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Two Populations ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

Here we reported that the Si-O-C nanoballs (SCONBs) were yielded from polyorganosiloxane, polydimethylsiloxane, by chemical vapor deposition (CVD) method. The composite nanoballs with a range of diameters from 50 to 200nm were composed of silicon, carbon and oxygen based on analysis of EDX. At the transmission electron microscope(TEM) and scan electronic microscope(SEM), two populations of nanoballs were found: around 200nm and 500nm. X-ray diffraction patterns demonstrated that the nanoballs were dominatingly amorphous. Temperature played an key role in size distribution of Si-O-C nanoballs, and the 850–900°C temperature range was typical for nanoparticles growth via CVD.

Microstructure and Mechanical Properties of TiAlON/TiAlN/TiAl Films

2014 ◽  
Vol 628 ◽  
pp. 93-97 ◽  
Author(s):  
Jun Zhang ◽  
Jia Jing Cai ◽  
Wei Zhao ◽  
Zheng Gui Zhang
Keyword(s):  
Mechanical Properties ◽  
Adhesive Strength ◽  
High Speed ◽  
High Speed Steel ◽  
Fracture Morphology ◽  
Liquid Droplets ◽  
X Ray Diffraction ◽  
Good Adhesive ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

TiAlON/TiAlN/TiAl hard films are prepared by multi-arc ion plating technology using the Ti-50Al (at%) alloy target. The high speed steel (HSS) is adopted as substrate. The surface and cross-fracture morphology, the surface and cross-fracture compositions and the phase structures of the as-deposited TiAlON/TiAlN/TiAl hard films are observed and measured by scan electronic microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties, including micro-hardness and adhesive strength between film and substrate, of the as-deposited TiAlON/TiAlN/TiAl hard films are investigated. The effects of oxygen partial pressure on the as-deposited films are discussed. It is revealed that the increase of oxygen decreased liquid droplets distribution density to some extent, caused complicated phase structure. Nevertheless, the good adhesive strength and the improved hardness with a maximum of 3900HV are achieved.

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