Abstract: 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.
Abstract: Homogeneous BaTiO3 nano-sized powders were successfully prepared by spray pyrolysis
using multiphase plasma under the air atmosphere. Particle size, morphology, crystal phase
and crystallinity of as-prepared powders were characterized by SEM and XRD. The effect
of starting precursor solution on the formation of nanoparticles was investigated. The use
of Ba/Ti aqueous solution derived from malic acid led to formation of cubic BaTiO3
nanoparticles with 50 nm size.
Abstract: 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.
Abstract: Barium titanate (BaTiO3) particles with average size of smaller than 100 nm were synthesized
by a hydrothermal process at 100°C to 300°C. The c- to a-axis ratios of the particles increased as
the synthesis temperature increased. Disk capacitors were fabricated with as-synthesized particles
and some additives to obtain X7R capacitors. The temperature coefficient of capacitance with
particles synthesized at 100°C was much larger than that for 300°C, indicating that the former had
uniform composition in the grain while the latter had a core-shell structure. This data show that
barium titanate particles hydrothermally synthesized at high temperature are useful when creating
the X7R capacitors with small grain size.
Abstract: For potassium niobate (KNbO3) single crystal, the 31 resonators with the highest piezoelectric constant d31
were designed using transformation of axis. We confirmed that the engineered domain configurations with
maximum d31 of –55.1 pC/N was caused by a combination between two polarization with polar directions
along c and [-101]c directions. Moreover, if there are larger piezoelectric constants from domain wall
region, we can expect the much higher piezoelectric properties. To induce the above domain
configuration, a new poling method using patterning electrode was investigated. In this study, the two
methods on the basis of temperature-induced phase transition at 207 °C and electric-field-induced phase
transition at room temperature were investigated.
Abstract: For the  oriented barium titanate (BaTiO3) single crystals, the patterning electrode was applied to induce
the finer engineered domain configurations with domain size of 3 2m. The poling treatment was performed
at 134 °C under electric fields below 6 kV/cm to inhibit the burning of the patterning electrode with
photoresist. As the results, the gradient domain sizes from 3 to 8-9 2m were induced into the 31 resonator.
The d31 was measured at -243.2 pC/N, and this value was almost 70 % of the expected d31 of –337.7 pC/N
for the resonator with domain size of 3 2m. This difference was originated from lower applied electric field
below 6 kV/cm. However, this study was revealed that the patterning electrode was very powerful tool to
induce much finer domain sizes below 5 2m.
Abstract: The morphology of wurtzite-type zinc oxide (ZnO) grown from an aqueous solution was
successfully controlled by addition of phosphate ions and various organic molecules having carboxy
groups. Basically, array of hexagonal needles with a diameter of 50–100 nm was grown on a
substrate in the absence of the additives. Hexagonal plates were perpendicularly arranged on the
substrate by the adsorption of citric, tartaric and maleic acids. The presence of phosphate ions
induced an open cellular structures consisting of zinc oxide nanosheets. Densely packed columns
and bundles consisting of nanoscale fibrous crystals were produced by the addition of bulky dye
molecules, such as phenolphthalein. The influence of the dye molecules depended on pH of the
solution. The morphological variation of ZnO films was ascribed to the selective adsorption of the
anionic species on the basal and prism planes of the wurtzite structure.
Abstract: To obtain porous alumina films, the precursor sol was prepared by hydrolysis of Al isopropoxide
and then mixing with poly(ethylene glycol) (PEG). The porous alumina films were fabricated by
dip-coating technique on glass substrates and heating at 500 °C. The film was composed of nano
sized particles (30-50 nm). The maximum thickness of the film prepared by one-run dip-coating
was ca. 1000 nm. The film had humidity-sensitive electrical resistance at room temperature.
Abstract: Multi-walled carbon nanotubes (MWCNTs) were synthesized from camphor by a chemical vapor
deposition (CVD) method in a range of 750-900. The catalyst was fed in three ways: (a) a
sputtered Fe-film on a quartz substrate (b) vaporized ferrocene in an Ar flow; (c) both of (a) and (b).
In the case (c), highly pure, dense and aligned MWCNT arrays formed on the quartz substrate at
850, whereas nonaligned MWCNTs formed in the cases (a) and (b).
Abstract: We report a fabrication of high-density nanodots by photodoping in overdoped Bi2Sr2CaCu2O8+d
thin film (Tc = 80 K). A scanning near-field optical microscope probe is used to locally excite
carrier, and photodoped region is associated with lower Tc phase (Tc = 75 K) via overdoping.
Nanoscale characterizations with optical reflectivity reveal that nanodots (30-nm diameter) are
regularly distributed in 50-nm step. The resultant films with photoinduced nanodots enhance Jc, a
situation being similar to strong pinning effects observed in films modified by either ion irradiation
or sputtered nanoparticles. These results suggest that photoinduced nanodots with lower Tc act as
effective pinning centers.