Size Dependence of Dielectric Properties for Barium Titanate Nanoparticles Prepared under Various Vacuum Atmospheres

2006 ◽  
Vol 320 ◽  
pp. 139-142 ◽  
Author(s):  
Satoshi Wada ◽  
Masanori Ohishi ◽  
Kayo Takizawa ◽  
Takuya Hoshina ◽  
Hirofumi Kakemoto ◽  
...  

Barium titanate (BaTiO3) fine particles were prepared using the 3-step thermal decomposition method of barium titanyl oxalate under various vacuum atmospheres. In this method, the first two steps prepared BaTiO3 nanoparticles with 30 nm, and at the 3rd step, BaTiO3 nanoparticles were heat-treated at various temperature and degree of vacuum. As a result, as degree of vacuum is high, particle size of BaTiO3 fine particles decreased. Moreover, the dielectric constant of BaTiO3 fine particles was measured using the powder dielectric measurement method with slurry. The dielectric constant of these particles showed the dielectric maximum of 4,320 at 200 nm despite degree of vacuum. This result revealed that degree of vacuum during particle growth of BaTiO3 particles had no relation about dielectric constant.

2009 ◽  
Vol 421-422 ◽  
pp. 506-509 ◽  
Author(s):  
Shuhei Kondo ◽  
Chikako Moriyoshi ◽  
Yoshihiro Kuroiwa ◽  
Satoshi Wada

Barium titanate (BaTiO3) nanoparticles were prepared by two-step thermal decomposition method of barium titanyl oxalate nanoparticles with a size of 30 nm. The BaTiO3 particle sizes were changed from 12.3 to 142 nm by control of temperature at 2nd step. The X-ray diffraction (XRD) measurement revealed that a clear splitting of 002 and 200 planes was observed over 40 nm, and the c/a ratio of 1.0089 was obtained for the BaTiO3 nanoparticles with a size of 62.3 nm. This high c/a ratio in the BaTiO3 nanoparticles suggested that its mesoscopic particle structure was composed of very thin surface cubic layer below 5 nm. Thus, synchrotron XRD data were analyzed using a “two layers” model and a “three layers” model. The Rietveld analysis using the three layers model resulted in the particle structure with a cubic layer thickness of 2.5 nm and structure gradient layer thickness of 7.5 nm. Finally, the dielectric constant of these BaTiO3 nanoparticles with thin surface cubic layer was measured at room temperature, and the maximum dielectric constant over 30,000 was obtained at the nanoparticles with a size of 83.6 nm.


2007 ◽  
Vol 350 ◽  
pp. 47-50 ◽  
Author(s):  
Takuya Hoshina ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
Satoshi Wada

Barium titanate (BaTiO3) nanoparticles with various particle sizes from 20 to 430 nm were prepared using a 2-step thermal decomposition method. Powder dielectric measurement clarified that dielectric constant of BaTiO3 particles with 140 nm exhibited a maximum around 5,000. To explain this high dielectric constant, THz-region dielectric properties of BaTiO3 nanoparticles, especially Slater transverse optic (TO) mode frequency, were estimated using the far infrared (FIR) reflection method. As the result, it was found that the Slater TO mode of BaTiO3 particles with 140 nm exhibited a minimum. Therefore, the high dielectric constant around 5,000 at 140 nm can be originated from the softening of the Slater TO mode.


2010 ◽  
Vol 445 ◽  
pp. 171-174 ◽  
Author(s):  
Shuhei Kondo ◽  
Tatsuya Kita ◽  
Petr Pulpan ◽  
Chikako Moriyoshi ◽  
Yoshihiro Kuroiwa ◽  
...  

Barium titanate (BaTiO3) nanoparticles were prepared by a two-step thermal decomposition method using barium titanyl oxalate nanoparticles of size 30 nm with and without dry-jet milling. Dry-jet milled barium titanyl oxalate nanoparticles (BTO-B) were well-dispersed whereas those without the dry-jet milling procedure (BTO-A) were partially aggregated. A heat annealing of obtained BaTiO3 nanoparticles at the same temperature resulted in crystallite sizes of the BTO-A derived BaTiO3 nanoparticles much smaller than those of the BTO-B derived. A mesoscopic particle structure analysis of revealed much thinner surface cubic layer thickness of the BTO-B derived BaTiO3 nanoparticles compared with the BTO-A derived BaTiO3 nanoparticles. This indicated the particle growth rate to be the most important parameter for the surface cubic layer thickness determination. A relationship between the surface cubic layer thickness and the particle growth rate was investigated precisely in this study.


2007 ◽  
Vol 350 ◽  
pp. 59-62 ◽  
Author(s):  
Kayo Takizawa ◽  
Takuya Hoshina ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
Yoshihiro Kuroiwa ◽  
...  

Barium titanate (BaTiO3) fine particles were prepared using the 2-step thermal decomposition method of barium titanyl oxalate. At the 2nd step of this method, the intermediate compound (Ba2Ti2O5·CO3) was decomposed into BaTiO3 and CO2 under various degrees of vacuum pressure. As a result, the particle size of prepared BaTiO3 nanoparticles decreased with decreasing pressure. Moreover, the dielectric constants of these BaTiO3 nanoparticles were measured using the powder dielectric measurement method using slurry. The dielectric constant of BaTiO3 nanoparticles increased with decreasing pressure at the same particle size. It is considered that mesoscopic particle structure controlled by vacuum pressure is important for the dielectric properties of BaTiO3 nanoparticles.


2012 ◽  
Vol 622-623 ◽  
pp. 897-900 ◽  
Author(s):  
Suryakanta Nayak ◽  
Tapan Kumar Chaki ◽  
Dipak Khastgir

Polymer-ceramic nanocomposites with controlled dielectric properties are prepared using poly(dimethylsiloxane) elastomer as base matrix and barium titanate as filler. Barium titanate (BaTiO3) used in this study is prepared by solid state reaction at high temperature. The effect of BaTiO3 nanoparticles on electrical and mechanical properties are extensively studied and found that dielectric constant of nanocomposites increases significantly with the increase in BaTiO3 concentration where as volume resistivity decreases continuously. Different mechanical properties are also studied for all the composites in order to find the effect of filler concentration. Morphology of the prepared BaTiO3 was studied by field emission scanning electron microscope (FESEM).


2007 ◽  
Vol 350 ◽  
pp. 31-34 ◽  
Author(s):  
Teruhisa Makino ◽  
Masashi Arimura ◽  
Kunitaka Fujiyoshi ◽  
Yoko Yamashita ◽  
Makoto Kuwabara

We synthesized barium titanate (BaTiO3) nanoparticles by sol-gel process and investigated their crystallization behavior using differential scanning calorimetry and X-ray diffraction. BaTiO3 nanoparticles with various degrees of crystallinity were obtained by adjusting synthesis conditions. Under aging conditions that do not allow dealcholization reaction to complete, many hydroxyl ligands remain in as-synthesized BaTiO3 nanoparticles, resulting in the formation of voids or defects in the nanoparticles after calcination. It is essential to use high concentration alkoxides precursor solutions for producing BaTiO3 nanoparticles with high crystallinity at low temperature.


2008 ◽  
Vol 388 ◽  
pp. 111-114 ◽  
Author(s):  
Satoshi Wada ◽  
Aki Nozawa ◽  
Masaru Ohno ◽  
Takaaki Tsurumi ◽  
Yoshihiro Kuroiwa

Barium titanate (BaTiO3) nanocube particles below 20 nm were prepared by solvothermal method. To prepare nanocubes, a selection of organic solvent and inorganic materials of Ba and Ti sourses was most important. At the temperatures above 200 °C, a nucleation and particle growth of BaTiO3 nanoparticles led to a formation of the BaTiO3 nanocubes with a size of 10-15 nm.


2006 ◽  
Vol 320 ◽  
pp. 131-134 ◽  
Author(s):  
Takuya Hoshina ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
Masatomo Yashima ◽  
Yoshihiro Kuroiwa ◽  
...  

Almost impurity-free, defect-free and dense barium titanate (BaTiO3) fine particles with various sizes from 20 to 430 nm were prepared by the 2-step thermal decomposition method and post-heating treatment. The crystal structures of these particles in the range from -150 to 150 °C were investigated using synchrotron radiation XRD measurement. The crystal structure refinement using Rietveld method revealed that BaTiO3 particles with the size over 40 nm were composed of two parts; (a) cubic shell and (b) core with successive phase transitions. The crystal structure of the core component can be related to the dielectric properties at room temperature. Moreover, it was revealed that the phase transition behavior of BaTiO3 nanoparticles was different from that of the BaTiO3 single crystal.


Author(s):  
Vuong Thi Vy Anh ◽  
Nguyen Thi Dung ◽  
Chu Ngoc Chai ◽  
Phan Thi Tuyet Mai ◽  
Nguyen Xuan Hoan

Barium titanate nanopowders, and composite materials of barium titanate/ graphene oxide (10 wt.% of graphene oxide according to the initial composite composition) were synthesized by hydrothermal method at the fixed reaction condition of 200 oC and 24 hours. The obtained powders were characterized by different techniques: X-ray diffraction, FTIR spectroscopy, Particles size distribution, and Scanning electron microscopy. Zeta potential measurement under electrophoretic mobility technique was also employed to investigate the stability of the BaTiO3 nanoparticles and composite materials of barium titanate/graphene oxide. The results showed that the BaTiO3 present with the tetragonal crystal structure (P4mm, a = 4.0000 Å, c = 4.0109 Å) and has uniform morphology with the grain sizes are in the range of 70 - 140 nm. The BaTiO3 nanoparticles were well distribution and covered on a surface of graphene oxide. The BaTiO3 nanoparticles, and BaTiO3/graphene oxide are stable in alkali, neutral media, and acidic media up to pH ~ 5.


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