Synthesis, Properties and Characterization of Red Phosphor Particles of Y2O3:Eu

1997 ◽  
Vol 3 (S2) ◽  
pp. 725-726
Author(s):  
Y. D. Jiang ◽  
Z. L. Wang ◽  
F. Zhang ◽  
H. G. Paris ◽  
C. J. Summers
Keyword(s):  
High Efficiency ◽  
Fine Particles ◽  
Average Diameter ◽  
Structure Characterization ◽  
Europium Oxide ◽  
Particle Sizes ◽  
Properties And Characterization ◽  
Field Emission Displays ◽  
Synthesis Properties ◽  
Commercial Applications

High resolution and high efficiency planar display, one of the national priorities for advanced technologies and commercial applications, require highly efficient phosphor materials with crystalline monodispersive fine particles [1,2]. Europium oxide activated yttrium oxide (Y2O3:Eu) is a potential red-emission phosphor powders to be used in high efficiency electroluminescence and field emission displays. In this paper, a novel hydrolysis technique is employed to prepare phosphor particles of Y2O3: Eu, and the structure characterization is reported.In this synthesis technique, urea reacts with water to release OH−, cations of Y3+ and Eu3+ combine with OH− to form (Y1−xEux)(OH)3 precipitates. Y2O3 particles doped with Eu are formed after the precipitates being fired at a given temperature [3]. The particles prepared by this method are nearly spherical, and have an average diameter of ∼200 nm (Fig. 1). The distribution of particle sizes is narrow, and almost no agglomeration among particles is observed. The particle sizes remain approximately the same before (Fig. 1a) and after (Fig. 1b) being fired at 1200°C.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

Synthesis, properties and characterization of the trinuclear clusters [Co3(µ-SR)6(PEt3)3]X (R = Me or Et, X = BPh4–or PF6–)

1996 ◽  
pp. 4337-4344 ◽  
Author(s):  
Pierluigi Barbaro ◽  
Franco Cecconi ◽  
Carlo A. Ghilardi ◽  
Stefano Midollini ◽  
Annabella Orlandini ◽  
...  
Keyword(s):  
Properties And Characterization ◽  
Synthesis Properties ◽  
Trinuclear Clusters

scholarly journals Features of Waste Chemical Processing Germanium Concentrates

2020 ◽  
Author(s):  
Igor Nikolaevich Tanutrov ◽  
Marina Nikolaevna Sviridova
Keyword(s):  
Chemical Properties ◽  
Average Diameter ◽  
Toxic Waste ◽  
High Temperature Treatment ◽  
High Dispersion ◽  
Chemical Processing ◽  
Particle Sizes ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

In order to increase the extraction of germanium in the technology of production of germanium concentrates, as well as finding ways to eliminate the accumulation of toxic waste using modern techniques and equipment, the physical and chemical properties of waste chemical processing of germanium concentrates (OHGC) of two domestic enterprises were experimentally studied. The main components of OHGC are: sulphate hemihydrate CaSO4·0.5H2O and hypochlorite Ca(OCl)2 calcium. The moisture content of the sludge amounted to 30–50 %. The content of germanium in the cakes of both companies is in the range of 0.20 and 0.27 %, respectively, indicating the feasibility of recovery in the Ge. At the same time, the samples of cakes differ significantly in the content of impurities, which depends on the types of raw materials in the preparation of concentrates. Granulometric composition of cakes is characterized by high dispersion. With an average diameter of 12 μm, all particle sizes are in the range of 0.5-15 μm. The distribution of particle sizes is shifted in interval of 0–15 μm, and the area of the particles less than 3 μm is not more than 10 %. The high dispersion of the cake is reflected in the specific surface area, which is 23.7 m2/g. Thermographic study found that the heating of the sample cake is accompanied by two endothermic effects of dehydration at 110 and 145–168 ∘C calcium sulfate and hypochloride semihydrate with corresponding weight loss of 13.1 and 12.9 %. The presence of toxic impurities (arsenic, zinc and lead), as well as chlorine, presents significant challenges for the development of disposal technology with the extraction of germanium. Assuming that the undiscovered part of the germanium in the concentrate is compounds or solid solutions with silicon dioxide, an effective technology should include their reagent high temperature treatment. Keywords: waste, germanium concentrate, chemical processing, waste, physical and chemical properties

scholarly journals Optical, microphysical and compositional properties of the Eyjafjallajökull volcanic ash

2014 ◽  
Vol 14 (9) ◽  
pp. 13271-13300 ◽  
Author(s):  
A. Rocha-Lima ◽  
J. V. Martins ◽  
L. A. Remer ◽  
N. A. Krotkov ◽  
M. H. Tabacniks ◽  
...  
Keyword(s):  
Refractive Index ◽  
Volcanic Ash ◽  
Fine Particles ◽  
Absorption Efficiency ◽  
Particle Sizes ◽  
Air Volume ◽  
Automatic Software ◽  
Compositional Properties ◽  
Size Distribution Of Particles ◽  
Mass Absorption Efficiency

Abstract. Microphysical, optical, and compositional properties of the volcanic ash from the April–May (2010) Eyjafjallajökull volcanic eruption are presented. Samples of the volcanic ash were taken on the ground in the vicinity of the volcano. The material was sieved, re-suspended, and collected on filters, separating particle sizes into coarse and fine modes. The spectral mass absorption efficiency αabs [m2 g−1] was determined for coarse and fine particles in the wavelength range from 300 to 2500 nm. Size distribution of particles on filters was obtained using a semi-automatic software to analyze images obtained by Scanning Electron Microscopy (SEM). The grain density of the volcanic ash was determined as 2.16(13) g cm−3 by measuring the variation of air volume in a system with volcanic ash and air under compression. Using Mie–Lorenz and T-matrix theories, the imaginary part of the refractive index was derived. Results show the spectral imaginary refractive index ranging from 0.001 to 0.005. Fine and coarse particles were analyzed by X-Ray fluorescence for elemental composition. Fine and coarse mode particles exhibit distinct compositional and optical differences.

Influence of Applied Magnetic Field on a Wire-Plate Electrostatic Precipitators Under Multi-Field Coupling

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Jian-Ping Zhang ◽  
Yong-Xia Dai ◽  
Jiong-Lei Wu ◽  
Jian-Xing Ren ◽  
Helen Wu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Fine Particles ◽  
Collection Efficiency ◽  
Mathematic Model ◽  
Average Diameter ◽  
Dust Particles ◽  
Particle Dynamic ◽  
Electrostatic Precipitators ◽  
The Magnetic Field

The aim of this work is to find an effective method to improve the collection efficiency of electrostatic precipitators (ESPs). A mathematic model of an ESP subjected to the external magnetic field was proposed. The model considered the coupled effects between the gas flow field, particle dynamic field and electromagnetic field. Particles following a Rosin-Rammler distribution were simulated under various conditions and the influence of the magnetic field density on the capture of fine particles was investigated. The collection efficiency and the escaped particle size distribution under different applied magnetic field intensities were discussed. Particle trajectories inside the ESP under aerodynamic and electromagnetic forces were also analyzed. Numerical results indicate that the collection efficiency increases with the increase of applied magnetic field. It was also found that a stronger applied magnetic field results in a larger particle deflection towards the dust collection plates. Furthermore, the average diameter of escaping particles decreases and the dispersion of dust particles with different sizes increases with the increasingly applied magnetic field. Finally, the average diameter decreases almost linearly with the magnetic field until it drops to a certain value. The model proposed in this work is able to obtain important information on the particle collection phenomena inside an industrial ESP under the applied magnetic field.

Millimetre-scale growth of single-wall carbon nanotube forests using an aluminium nitride catalyst underlayer

MRS Advances ◽  
2019 ◽  
Vol 4 (3-4) ◽  
pp. 177-183
Author(s):  
Takashi Tsuji ◽  
Naoyuki Matsumoto ◽  
Hirokazu Takai ◽  
Shunsuke Sakurai ◽  
Don N. Futaba
Keyword(s):  
Carbon Nanotube ◽  
Photoelectron Spectroscopy ◽  
High Efficiency ◽  
Ostwald Ripening ◽  
Average Diameter ◽  
Aluminium Nitride ◽  
High Yield ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Carbon Nanotube Forests

ABSTRACTWe have demonstrated the high yield (∼900 μm) and highly single-wall selective (>95%) growth of carbon nanotube (CNT) forest using aluminium nitride (AlN) as a catalyst underlayer. Such high efficiency and single-wall selectivity have not been previously reported using this underlayer system. Evaluation with transmission electron microscopy showed that the average diameter of the grown carbon nanotubes was ∼3.0 nm, which is similar to those grown on alumina underlayers. In addition, characterization of the catalyst/underlayer system using atomic force microscopy and X-ray photoelectron spectroscopy suggests that neither Ostwald ripening along the surface nor catalyst subsurface diffusion into the AlN underlayer are severely occurring at the growth temperature, leading to the creation of the stable and dense small nanoparticle array to achieve an efficient growth of single-wall CNTs.

scholarly journals Size-segregated characteristics of organic carbon (OC), elemental carbon (EC) and organic matter in particulate matter (PM) emitted from different types of ships in China

2020 ◽  
Vol 20 (3) ◽  
pp. 1549-1564 ◽  
Author(s):  
Fan Zhang ◽  
Hai Guo ◽  
Yingjun Chen ◽  
Volker Matthias ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Elemental Carbon ◽  
Fine Particles ◽  
Particle Mass ◽  
Fuel Oil ◽  
Chemical Compositions ◽  
Particle Sizes ◽  
Heavy Fuel Oil ◽  
Different Types ◽  
Marine Diesel

Abstract. Studies of detailed chemical compositions in particles with different size ranges emitted from ships are in serious shortage. In this study, size-segregated distributions and characteristics of particle mass, organic carbon (OC), elemental carbon (EC), 16 EPA polycyclic aromatic hydrocarbons (PAHs) and 25 n-alkanes measured aboard 12 different vessels in China are presented. The results showed the following. (1) More than half of the total particle mass, OC, EC, PAHs and n-alkanes were concentrated in fine particles with aerodynamic diameter (Dp) < 1.1 µm for most of the tested ships. The relative contributions of OC, EC, PAH and alkanes to the size-segregated particle mass are decreasing with the increase in particle size. However, different types of ships showed quite different particle-size-dependent chemical compositions. (2) In fine particles, the OC and EC were the dominant components, while in coarse particles, OC and EC only accounted for very small proportions. With the increase in particle size, the OC / EC ratios first decreased and then increased, having the lowest values for particle sizes between 0.43 and 1.1 µm. (3) Out of the four OC fragments and three EC fragments obtained in thermal–optical analysis, OC1, OC2 and OC3 were the dominant OC fragments for all the tested ships, while EC1 and EC2 were the main EC fragments for ships running on heavy fuel oil (HFO) and marine-diesel fuel, respectively; different OC and EC fragments presented different distributions in different particle sizes. (4) The four-stroke low-power diesel fishing boat (4-LDF) had much higher PAH emission ratios than the four-stroke high-power marine-diesel vessel (4-HMV) and two-stroke high-power heavy-fuel-oil vessel (2-HHV) in fine particles, and 2-HHV had the lowest values. (5) PAHs and n-alkanes showed different profile patterns for different types of ships and also between different particle-size bins, which meant that the particle size should be considered when source apportionment is conducted. It is also noteworthy from the results in this study that the smaller the particle size, the more toxic the particle was, especially for the fishing boats in China.

The Research of Splitting Craft for Air Filter with Sea-Island Superfine Fiber Needled Fabrics

2013 ◽  
Vol 303-306 ◽  
pp. 2567-2571 ◽  
Author(s):  
Ling Xiao Jing ◽  
Sheng Sun ◽  
Xin Wang ◽  
Cai Qian Zhang
Keyword(s):  
Loss Rate ◽  
High Efficiency ◽  
Fine Particles ◽  
Orthogonal Design ◽  
Low Cost ◽  
Dust Collector ◽  
Air Filter ◽  
Ultra Fine Particles ◽  
Superfine Fiber ◽  
Splitting Time

Although the bag-type dust collector is dust capture equipment which is low cost and high efficiency, it has less filter efficiency to ultra fine particles for its of thicker fiber. So ultrafine fiber were used by bicomponent fiber with splitting craft to improve the filtration efficiency of ultra fine particles greatly. A piece of polyester/nylon sea-island superfine fiber needled nonwovens were splitted processing for nine times by the orthogonal design. And fibre microscopic photographs, weight loss rate and strength were analyzed. The best choice of splitting craft as followed: lye concentration is 16%, splitting time 15 min and splitting temperature is 95 °C.

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