Synthesis and characterization of TiO2 nanocrystalline powder prepared by homogeneous precipitation using urea

2003 ◽  
Vol 18 (3) ◽  
pp. 571-577 ◽  
Author(s):  
Dong Seok Seo ◽  
Hwan Kim ◽  
Hang Chul Jung ◽  
Jong Kook Lee
Keyword(s):  
Particle Size ◽  
Particle Shape ◽  
Elevated Temperatures ◽  
Treatment Temperature ◽  
Precipitation Method ◽  
Nanocrystalline Powder ◽  
Homogeneous Precipitation ◽  
Homogeneous Precipitation Method ◽  
Good Crystallinity

TiO2 nanocrystalline powder was synthesized by homogeneous precipitation method using urea, and its characteristics were investigated through comparison with the powder prepared by conventional precipitation using ammonia. The homogeneously precipitated powder was anatase-type TiO2 with a particle size of 4–5 nm and a uniform spherical particle shape. The fact that the transformation from anatase to rutile was prohibited at elevated temperatures in the homogeneously precipitated powder can be useful to prepare anatase-type TiO2 thin films by calcination at high temperatures. With increasing heat-treatment temperature, the particle size of the homogeneously precipitated powder was smaller than that of the conventionally precipitated powder, and the particle shape was more uniform. The homogeneously precipitated powder showed good photocatalytic activity for Ag ion photoadsorption because the powder had both good crystallinity and a large specific surface area of 280 m2/g.

Synthesis and Characterization of Nanocrystalline Ceria Powder through Homogeneous Precipitation Method

2012 ◽  
Vol 557-559 ◽  
pp. 567-571
Author(s):  
Jin Liang ◽  
Hong Chen
Keyword(s):  
Particle Size ◽  
Orthogonal Experiment ◽  
Fluorite Structure ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Homogeneous Precipitation Method ◽  
Nanocrystalline Ceria

Nanocrystalline ceria powder was prepared through homogeneous precipitation method, orthogonal experiment was designed to figure out the most important factor that influence the particle size of the resultant and the optimum condition. X-ray diffraction revealed that the as-prepared nanoscale ceria powder had cubic fluorite structure, TEM image showed that the ceria powder was weakly agglomerated with a particle size of about 10 nm.

Synthesis of Spherical Zinc Oxide Micro-Flower via an Electric Field-Assisted Homogeneous Precipitation Method

2011 ◽  
Vol 328-330 ◽  
pp. 1541-1544 ◽  
Author(s):  
Xiu Juan Liang ◽  
Xiao Fang Hu ◽  
Xing Xing Weng ◽  
Da Wei Hu ◽  
Hai Xu Ji
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Zinc Oxide ◽  
Electric Field ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Homogeneous Precipitation Method ◽  
Ft Ir ◽  
Particle Size And Morphology ◽  
Size And Morphology

This paper presents the experimental results on electric field-assisted synthesis of spherical Zinc Oxide (ZnO) micro-flower in an homogeneous precipitation method. The synthesis processes with and without an electric field were compared. The products were characterized via SEM, XRD, TGA and FT-IR spectrum. The results show that the spherical ZnO micro-flower composed of ZnO single crystalline nanoparticles have thickness of about 10nm, width of about 50nm.The SEM results show that the application of an electric field caused the morphology transformation from flake-like to flower-like. It was found that an electric field had an effect on the crystal structure,the particle size and morphology.

Upconversion luminescence properties of monodisperse spherical Y2O2S:Yb,Ho nanocrystals

2009 ◽  
Vol 24 (5) ◽  
pp. 1756-1760 ◽  
Author(s):  
Xixian Luo ◽  
Wanghe Cao ◽  
Mingming Xing
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Formation Mechanism ◽  
In Vivo Imaging ◽  
Upconversion Luminescence ◽  
Green Emission ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Homogeneous Precipitation Method

Monodisperse spherical Y2O2S:Yb,Ho nanocrystals with particle size about 50 nm were prepared by a modified homogeneous precipitation method combined with low-temperature sulfurization process. The Y2O2S:Yb,Ho nanocrystals exhibit an intense green emission assigned to the Ho3+ ions 5F4, 5S2 → 4I15/2 transition under 980 nm infrared pump. The upconversion luminescence brightness of Y2O2S:Yb,Ho is 526 Cd/m2 under 4.63 W/cm2 pump density, indicating that the as-prepared Y2O2S:Yb,Ho nanocrystals can meet the requirement of in vivo imaging. The formation mechanism of monodisperse spherical oxysulfide nanoparticles is also discussed.

Synthesis and Characterization of BaCO3 Nanoparticles with Different Morphologies by Microwave Homogenous Precipitation

2013 ◽  
Vol 32 (1) ◽  
pp. 47-50
Author(s):  
Guo Chen ◽  
Jin Chen ◽  
Lijun Liu ◽  
C. Srinivasakannan ◽  
Jinhui Peng
Keyword(s):  
Raw Materials ◽  
Precipitation Method ◽  
Synthesis And Characterization ◽  
Homogeneous Precipitation ◽  
Tetraacetic Acid ◽  
X Ray ◽  
Homogeneous Precipitation Method ◽  
Scanning Electron ◽  
Composition Of Products

AbstractBaCO3 nanoparticles with different morphologies including needle-like, rod-like, bird's nest-like and flower-like have been successfully synthesized by the microwave homogeneous precipitation method using BaCl2·2H2O, NaOH and (NH2)2CO as raw materials with the help of different guide reagents, such as citric acid (CA), sodium triphosphate (STPP) and ethylene diamine tetraacetic acid (EDTA). Their phases and morphologies were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), respectively. The characterization results show that different guide reagents have little effect on the phase structure and composition of products while they play significant roles in determining the morphology of products. All the synthesized BaCO3 nanoparticles have typical orthorhombic structures that are well-crystallized.

Synthesis of Calcium Carbonate from Calcium Chlorine Solution Using Homogeneous Precipitation Method

2005 ◽  
Vol 486-487 ◽  
pp. 542-545 ◽  
Author(s):  
Kyung Nam Kim ◽  
Dae Yong Shin ◽  
Se Gu Son ◽  
Yong Do Kim
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Reaction Conditions ◽  
Homogeneous Precipitation Method ◽  
Reaction Solution ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Hydrolysis Of

Calcium carbonate(CaCO3) was synthesized from aqueous CaCl2 solution, using the homogeneous precipitation technique, which uses the hydrolysis of urea. The effects of reaction conditions on the morphology of CaCO3 were examined at 50-90°C. Particle size of CaCO3 decreases, as the concentrations of urea and [Ca2+] are increased. Calcite is produced more, as the concentration of [Ca2+] is increased. Method to stir the reaction solution affects significantly the particle size and morphology of CaCO3. Uniform needle-like aragonite particles were obtained, when left at 90°C for 4hours without stirring.

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