scholarly journals Barium Titanate Nanoparticles Formed by Chlorine-Free Ambient Condition Sol Process Using Tetrabutylammonium Hydroxide

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Wooje Han ◽  
Byungwook Yoo ◽  
Hyung-Ho Park
Keyword(s):  
Particle Size ◽  
Dielectric Constant ◽  
Barium Titanate ◽  
Ambient Condition ◽  
Molar Ratio ◽  
Diffraction Measurement ◽  
Capping Agent ◽  
Synthetic Control ◽  
Tetrabutylammonium Hydroxide ◽  
Particle Size Range

Barium titanate (BaTiO3: BTO) nanoparticles (NPs) were synthesized by chlorine-free ambient condition sol (ACS) process using heat reflux at low temperature of 90°C. The size distribution and morphology of BTO NPs were investigated by varying the concentration of tetrabutylammonium hydroxide (TBAH). The crystalline size of BTO NPs was decreased with increasing the amount of TBAH capping agent (average size changes from 54.3 to 38.7 nm for 0 to 0.5 M TBAH in X-ray diffraction measurement). The particle size of BTO NPs was principally controlled by a synthetic control of butyl chain of TBAH and also a steric effect of excess amount of TBAH. The dielectric constant of BTO NPs was decreased from 152 to 144 at 1 MHz after an adoption of TBAH capping agent with almost uniform dielectric loss (<0.027). But the dielectric constant of BTO NPs synthesized with various molar ratio of TBAH (0.1, 0.3, and 0.5) did not show a distinguished decrease. At the particle size range in this experiment, the dielectric behavior of BTO NPs was found to be mainly dependent on the TBAH ligands at BTO NPs formed during capping process, not on the size of BTO NPs.

Preparation of Potassium Niobate/Barium Titanate Nanocomposite Ceramics with a Wide Barium Titanate Particle Size Distribution and their Dielectric Properties

2013 ◽  
Vol 582 ◽  
pp. 76-79
Author(s):  
Ichiro Fujii ◽  
Kenta Yamashita ◽  
Kouichi Nakashima ◽  
Yoshinori Fujikawa ◽  
Daisuke Tanaka ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Barium Titanate ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Molar Ratio ◽  
Narrow Particle Size Distribution ◽  
Potassium Niobate ◽  
Barium Titanate Powder ◽  
Wide Particle Size Distribution

Denser, solvothermally synthesized KNbO3 (KN) / BaTiO3 (BT) composites with heteroepitaxial interfaces were prepared using the barium titanate powder with a wide particle size distribution. The relative density was 68 - 80 %, which was larger than that of the composites prepared using the barium titanate powder with a narrow particle size distribution. The dielectric constant was 300 450 and it was maximized at the KN/BT molar ratio of 0.5. The origin was discussed with the microstructure and crystal structure.

Near-Stoichiometric Barium Titanate Synthesis by Low Temperature Hydrothermal Reaction

1999 ◽  
Vol 606 ◽  
Author(s):  
Kyoungja Woo ◽  
Guang J. Choi ◽  
Young S. Cho
Keyword(s):  
Particle Size ◽  
Barium Titanate ◽  
Low Temperature ◽  
Hydrothermal Reaction ◽  
Ultrafine Particle ◽  
Molar Ratio ◽  
Barium Ions ◽  
Strong Force ◽  
Cubic Form ◽  
Tetragonal Form

AbstractBarium-deficiency of barium titanate particles prepared by low temperature hydrothermal reaction has been notorious. It has been believed that barium-deficiency is caused by the high solubility of barium source compared with titanium. Here is reported the synthesis of nearstoichiometric barium titanate powders with ultrafine particle size and high crystallinity by low temperature hydrothermal reaction from barium acetate and titanium tetra(methoxyethoxide). Barium titanate particles were synthesized in the spherical, metastable cubic crystalline grains with size distribution between 60 ∼ 90 nm in diameter. Ultrafine particle size was resulted from the control of the hydration rate and the decrease of Ti-O-Ti cross-linking extent of titanium precursor. Increasing barium to titanium molar ratio in reactant could not overcome the notorious barium-deficiency but, improved stoichiometry and produced finer and less agglomerated particles. Interestingly, adding a slight pressure to autogeneous one to make total 4 ∼ 10 atm has yielded near-stoichiometric, highly crystalline, and less agglomerated barium titanate particles. It seems like that the total pressure around 4 ∼ 10 atm provides strong force enough to push barium ions into the interstitial points of perovskite structure and stabilize it. These particles, which were in metastable cubic form as synthesized, initiated phasetransition to tetragonal form by calcination at 400 °C.

Application of Experimental Statistical Method in Optimizing Preparation Variables for Cu-Ni/TiO2 Photocatalyst

2014 ◽  
Vol 625 ◽  
pp. 856-859 ◽  
Author(s):  
Robabeh Bashiri ◽  
Norani Muti Mohamed ◽  
Chong Fai Kait ◽  
Suriati Sufian
Keyword(s):  
Particle Size ◽  
Response Surface ◽  
Polynomial Regression ◽  
Antagonistic Effect ◽  
Molar Ratio ◽  
Coefficient Of Determination ◽  
Particle Size Range ◽  
Adsorptive Property ◽  
Cu Content ◽  
Contour Plots

Cu-Ni/TiO2 was prepared using sol–hydrothermal method. Response surface Method (RSM) including central composite design (CCD) was applied to study the single and combined effects of three primary preparation parameters like water to alkoxide molar ratio (A), acid to alkoxide molar ratio (B), and Cu content (C) on the growth of Cu-Ni doped TiO2 particle size. The particle size range of the photocatalysts was 13−25 nm. Analysis of variance (ANOVA) revealed a second–order polynomial regression model to fit the experimental data in CCD. A comparison between predicted and experimental values has depicted a good agreement amongst them with high coefficient of determination value (R2= 0.98). The 3-D response surface and the contour plots imply a synergistic effect of parameter A, an antagonistic effect of parameter B, and significant interaction between them on the growth of particle sizes more than parameter C and its interactions with other variables. The smaller average sizes of Cu-Ni doped TiO2 particles with higher surface area are helpful to increase the light adsorptive property in hydrogen production studies.

scholarly journals DEPENDENCE OF THE STABILITY OF THE FERROELECTRIC PHASE OF POTASSIUM NITRATE IN A COMPOSITE WITH BARIUM TITANATE ON THE VOLUME AND SIZE OF INCLUSION PARTICLES

2020 ◽  
pp. 30-36
Author(s):  
NIKITA SERGEEVICH KONTES ◽  
◽  
ELENA VLADIMIROVNA STUKOVA ◽  
IRINA ANATOLYEVNA GOLUBEVA ◽  
OKSANA VASILIEVNA ZOTOVA ◽  
...  
Keyword(s):  
Particle Size ◽  
Dielectric Constant ◽  
Barium Titanate ◽  
Ferroelectric Phase ◽  
Volume Fraction ◽  
Potassium Nitrate ◽  
Ferroelectric State ◽  
The Stability

The results of a study of composites (KNO3) 1 -x /(BaTiO3)x (x = 0.1 and 0.2) are presented. It is shown that the stability of the ferroelectric state of potassium nitrate increases with an increase in the volume fraction of inclusions. It was found that the stability of the ferroelectric phase of potassium nitrate in the composite is also influenced by the particle size of the inclusions. It was revealed that the values of the dielectric constant in the region of the ferroelectric phase increase with an increase in the particle size of the inclusions.

381. Sampling Efficiencies of Three Personal Aerosol Samplers within and Beyond the Inhalable Particle Size Range

2001 ◽  
Author(s):  
V. Aizenberg ◽  
P. Baron ◽  
K. Choe ◽  
S. Grinshpun ◽  
K. Willeke
Keyword(s):  
Particle Size ◽  
Size Range ◽  
Particle Size Range

scholarly journals Feasibility of fly ash as fluxing agent in mid- and low-grade phosphate rock carbothermal reduction and its reaction kinetics

2021 ◽  
Vol 10 (1) ◽  
pp. 157-168
Author(s):  
Biwei Luo ◽  
Pengfei Li ◽  
Yan Li ◽  
Jun Ji ◽  
Dongsheng He ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Reaction Time ◽  
Carbothermal Reduction ◽  
Industrial Waste ◽  
Phosphate Rock ◽  
Molar Ratio ◽  
Low Grade ◽  
Carbon Excess ◽  
Fluxing Agent

Abstract The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

COMPARATIVE STUDY OF DIELECTRIC BEHAVIOR OF Mn0.4Zn0.6Fe2O4 NANOFERRITE BY CITRATE PRECURSOR METHOD

2008 ◽  
Vol 22 (16) ◽  
pp. 2537-2544 ◽  
Author(s):  
PREETI MATHUR ◽  
ATUL THAKUR ◽  
M. SINGH
Keyword(s):  
Particle Size ◽  
Dielectric Constant ◽  
Comparative Study ◽  
Average Particle Size ◽  
Dielectric Behavior ◽  
Average Particle ◽  
Oxidizing Agent ◽  
Precursor Method ◽  
Citrate Precursor ◽  
Citrate Precursor Method

In the present work, comparative study of the dielectric behavior of Mn 0.4 Zn 0.6 Fe 2 O 4 ferrite synthesized with and without H 2 O 2 (hydrogen peroxide) has been presented. The dc resistivity has been improved by the citrate precursor method as compared to the ceramic method, and it is further improved by the addition of H 2 O 2, which acts as a strong oxidizing agent. We have shown by means of X-ray diffraction that the resulting ferrite is made up of nanocrystallites and the average size of these nanocrystallites–calculated by Scherrer's formula–depends on the polarizer. The average particle size was found to be ~70 nm with H 2 O 2 and ~88 nm without H 2 O 2. The particle size is further confirmed by scanning electron microscopy. Both the results are found to be in good agreement. The decrease in dielectric constant and dielectric loss factor by addition of oxidizing agent is justified by inverse proportionality between the resistivity and dielectric constant. Possible mechanisms contributing to these processes have been discussed.

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