• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.63-67
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• 2003

Synthesis of $PbLaTiO_{3}$ : Mn powders containing La and Mn was carried out using $PbO,\;TiO_{2},\;La_{2}O_{3}\;and\;MnO_{2}$ as starting materials by hydrothermal method. In the synthesis of single phase $PbLaTiO_{3}$ : Mn powder containing La and Mn, the optimal x value corresponding to La substitution was 0.01 which corresponds to $0.99(Pb_{1-x}La_{2x/3}TiO_{3})+0.01MnO_{2}$. The optimal conditions for the preparation of the powder synthesis were 8 M-KOH solvent of hydrothermal solvent, $270^{\circ}C$ of reaction temperature and 24 hrs of run time. It was found that the synthesized powders had spherical morphology with average particle size of 70 nm and specific surface area of $5.5\;m^{2}/g$.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.448-454
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• 2007

Hydrothermal synthesis was conducted with starting material as Barium hydroxide and hydrous titania ($TiO_2{\cdot}xH_2O$) to obtain barium titanate fine Powder. The conversion, crystal structure and properties of as-prepared powder were investigated according to reaction temperature, time and concentration. The effect of variables on conversion was in order of time < temperature < concentration and the maximum conversion reached to 99.5% in the case of hydrothermal synthesis at $180^{\circ}C$ for 2 h with 2.0 M reactant concentration. At low concentration such as 0.25 M, formation of unreacted $BaCO_3$ and $TiO_2$ was not inevitable at even high reaction temperature and these components converted into $BaTi_2O_5$ at high temperature and remained as impurity. As concentration of reactant increased, the size of as-synthesized $BaTiO_3$ powder deceased and Ba/Ti molar ratio approached into 1, showing Ba/Ti ratio of $1{\pm}0.005$ for reaction at $180^{\circ}C$ for 2 h with 2.0 M concentration.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.628-634
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• 2002

Formation rate of tetragonal BaTiO$_3$powder by hydrothermal synthesis and its dielectric property were studied. Submicron tetragonal BaTiO$_3$ powders were prepared hydrothermally, using Ba(OH)$_2$.8$H_2O$, TiO$_2$(anatase) and KOH as starting chemicals. Characterization via X-ray diffractometry, field emission scanning electron microscopy confirmed that increasing calcination temperatures(from 1100 to 130$0^{\circ}C$) promotes the formation of tetragonal BaTiO$_3$. Tetragonal BaTiO$_3$ ceramics, obtained by calcining at 1200 for 3 h after hydrothermal synthesis at 200 for 168 h, exhibited submicron size of 0.5 ~ 0.7 ${\mu}{\textrm}{m}$ and high relative permittivity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.33-38
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• 2014

In this work, according to temperature and time of hydrothermal synthesis, the electrochemical properties of $TiO_2$ particle using TTIP based on changing temperature and time in the hydrothermal synthesis were analyzed and optimized temperature and time were derived. When hydrothermal synthesis temperature and time were $200^{\circ}C$ and 1 h, respectively. The fabricated DSSC delivered the best electrochemical properties. In that case, $TiO_2$ particle size was 13.08 nm, electron transport time was $2.34{\times}10^{-3}s$ and recombination time was $4.01{\times}10^{-2}s$. The lowest impedance of $13.52{\Omega}$ and Voc, Jsc, FF is 0.70 V, $1.50mAcm^{-2}$, 65.62%, respectively and corresponding efficiency of 5.34% was considered as the optimal.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.3
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• pp.91-95
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• 2020

In this study, we report a hydrothermal synthesis in which BaTiO₃ nanoparticles (NPs) with enhanced size uniformity and dispersibility are synthesized by increased time and temperature, increasing nucleation and diffusion rates. The formation process of an uniform size of 20 nm BaTiO₃ NPs, which has not been extensively researched, was optimized through hydrothermal synthesis at 180℃. Simultaneous increase in the nucleation rate of TiO₂ and diffusion length of Ba²⁺ ions, resulting from a higher temperature, allowed for the synthesis of BaTiO₃ NPs (20 nm) with significantly enhanced size-uniformity. The size and crystallinity of BaTiO₃ NPs which exhibit excellent dispersibility in hexane solvent were investigated using transmission electron microscopy and X-ray diffraction. The results presented herein provide insights into improving the size uniformity and dispersibility of BaTiO₃ NPs by hydrothermal synthesis for applications to variety of electronic devices.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.129.2-129.2
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• 2007

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.543-550
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• 2010

This paper investigated the synthesis conditions of nano-sized $TiO_2$ powder in a hydrothermal process at a temperature range of $100{\sim}180^{\circ}C$ considering the precipitation agent, precipitation pH, reaction temperature and time. Titanium hydroxide formed by $NH_4OH$ exhibited a lower crystallization temperature than that by NaOH and formed less aggregated $TiO_2$ particles. As the precipitation pH increased above 8, the shape of the particles changed from spherical to needle form, which appeared to be caused by dissolution and re-precipitation of the titanium hydroxide in an alkali environment.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.77-77
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.219-219
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• 2005

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.561-564
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• 2015

Nano-size $BaTiO_3$ powder was synthesized by relatively simple hydrothermal reaction method. Finely dispersed Ti hydroxide precursor was first precipitated using $Ti(SO_4)_2$ and NaOH solution by applying ultrasonic power and washed thoroughly to remove $SO_4{^{2-}}$ and $Na^+$ ion. Then hydrothermal reaction was done at $160^{\circ}C$ for 6 hrs using solution prepared by washed Ti hydroxide precursor slurry and $Ba(OH)_2{\cdot}8H_2O$ with Ti:Ba mole ratio of 1:1. 200 ~ 500 nm size and uniform size distributed $BaTiO_3$ powder was synthesized by relatively low temperature and simple process.