Barium titanate (high‐k dielectric material) nano‐powders (approx

Hirose, 'Dependence of the Crystal Structure on Particle Size in Barium Titanate,' J.

Hydrothermal Synthesis of Barium Titanate - Industrial ..

AB - Near-stoichiometric BaTiO3 powders with ultrafine particle size and high crystallinity were prepared by low temperature hydrothermal reaction of Ba(OAc)2 and Ti(OCH2CH2OCH3)4. BaTiO3 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, Ti(OCH2CH2OCH3)4, which gives electronic, steric, and weakly chelating effect to titanium ion. Increasing the Ba/Ti mole ratio in reactant could not overcome the notorious Ba-deficiency but, improved stoichiometry and produced finer and less agglomerated particles. Interestingly, adding a slight pressure to autogeneous hydrothermal condition (total 4-10 atm) has yielded near-stoichiometric, highly crystalline, and less agglomerated BaTiO3 particles. These particles, which were in metastable cubic form as synthesized, initiated phasetransition to tetragonal form by calcination at below 400 °C.

Schreinemacher, 'Defect Chemistry and Microstructure of Hydrothermal Barium Titanate,' J.

Synthesis of Barium Titanate by Hydrothermal Method …

AB - A morphology-controlled synthesis of barium titanate (BaTiO3) nanostructures from nano-whiskers to nanoparticles, were prepared via a hydrothermal strategy by manipulating the alkalinity and reaction temperature. Initially, the K2Ti4O9 precursors almost remain unchanged in the temperature of 80-160 °C at 0.1 M. By increasing the alkalinity and temperature, the BaTiO3 nanostructures initially undergoes ion exchange with precursors while retaining the morphology at the self-sacrifice of K2Ti4O9 nano-whiskers, followed by the formation of BaTiO3 nano-maces. Finally, recrystallization occurs and converts into nanoparticles at 120-220 °C at 0.8 M. Also, time-dependent experiment was conducted to probe the ion exchange process. The formation mechanism involves the generation of chemical site inducing the ion exchange process and the dissolution-precipitation reaction. By investigating the synthesis and morphology evolution of one-dimensional BaTiO3 nanostructures, this work may be of great significance for fabrication of other perovskite-type MTiO3 (M = Ca, Sr, Pb).

Jiao, 'Solvethermal Synthesis and Characterization of Barium Titanate Powders,' J.

Nanocrystalline tetragonal barium titanate (BaTiO3) with particle sizes ranging from 30 to 100 nm were synthesized via microwave-hydrothermal routes at various fixed microwave frequencies and also using variable frequency with 1-5 s sweep times. The effects of microwave frequency, microwave bandwidth sweep time, and aging time on the microstructure, particle sizes, phase purity, surface areas, and porosities of the as-prepared BaTiO3 were investigated systematically. The crystallized BaTiO3 powders were characterized by X-ray diffraction, Raman spectroscopy, thermal analysis, infrared spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy with an EDS analyzer. The results show that the particle sizes, morphologies, and surface areas of the products are influenced by the microwave frequency and bandwidth sweep time. High microwave frequency (5.5 GHz) and variable frequency (3-5.5 GHz to 1 s) led to spherical particles with narrow and more uniform particle size distributions. BaTiO3 prepared using the standard 2.45 GHz yielded particles with a cubic microstructure. The surface areas of the prepared powders decreased with aging time using 4.0 and 5.5 GHz, but increased gradually with extended aging time in variable frequency (3-5.5 GHz to 1 s) processing. The dependence of properties of barium titanate on microwave frequency could be due to different transverse magnetic modes at different frequencies. For comparison purposes, conventional hydrothermal experiments were also performed under similar conditions as in microwave hydrothermal routes.

Barnea, 'X-Ray and Neutron Diffraction Study of Tetragonal Barium Titanate,' Acta Cryst., A26 336 (1970)


2 Synthesis of Barium Titanate using Hydrothermal process 3.2 ..

Due to the closed nature of the hydrothermalsystem and the desire for particles of decreased size, experimentaldesigns were employed to investigate the effects of various synthesisprocess treatments on the final particle attributes using low reactiontemperatures ({≤}210sp°C) and reaction times ≤30 min.

The synthesis of barium titanate ceramic ..

A morphology-controlled synthesis of barium titanate (BaTiO3) nanostructures from nano-whiskers to nanoparticles, were prepared via a hydrothermal strategy by manipulating the alkalinity and reaction temperature. Initially, the K2Ti4O9 precursors almost remain unchanged in the temperature of 80-160 °C at 0.1 M. By increasing the alkalinity and temperature, the BaTiO3 nanostructures initially undergoes ion exchange with precursors while retaining the morphology at the self-sacrifice of K2Ti4O9 nano-whiskers, followed by the formation of BaTiO3 nano-maces. Finally, recrystallization occurs and converts into nanoparticles at 120-220 °C at 0.8 M. Also, time-dependent experiment was conducted to probe the ion exchange process. The formation mechanism involves the generation of chemical site inducing the ion exchange process and the dissolution-precipitation reaction. By investigating the synthesis and morphology evolution of one-dimensional BaTiO3 nanostructures, this work may be of great significance for fabrication of other perovskite-type MTiO3 (M = Ca, Sr, Pb).

P a g e .1 used during the complete synthesis of barium titanate

N2 - A morphology-controlled synthesis of barium titanate (BaTiO3) nanostructures from nano-whiskers to nanoparticles, were prepared via a hydrothermal strategy by manipulating the alkalinity and reaction temperature. Initially, the K2Ti4O9 precursors almost remain unchanged in the temperature of 80-160 °C at 0.1 M. By increasing the alkalinity and temperature, the BaTiO3 nanostructures initially undergoes ion exchange with precursors while retaining the morphology at the self-sacrifice of K2Ti4O9 nano-whiskers, followed by the formation of BaTiO3 nano-maces. Finally, recrystallization occurs and converts into nanoparticles at 120-220 °C at 0.8 M. Also, time-dependent experiment was conducted to probe the ion exchange process. The formation mechanism involves the generation of chemical site inducing the ion exchange process and the dissolution-precipitation reaction. By investigating the synthesis and morphology evolution of one-dimensional BaTiO3 nanostructures, this work may be of great significance for fabrication of other perovskite-type MTiO3 (M = Ca, Sr, Pb).