Nanosize Barium Titanate Powder for New Generation of Passive Electronic Components
BaTiO3 NanoPowders
Description
The miniaturization of the electronic components, in par-
ticular the passive components like multilayer ceramic ca-
pacitors, is a rapidly developing area of R&D worldwide.
The multilayer ceramic capacitor (MLCC) with dielectric
formulations based on the ferroelectric compound BaTiO3
already compete with conventional high-capacitance Al- or
Ta-electrolytic capacitors. Utilization of nanosized particles
and nanostructured bulk ceramics is the most promising
way to improve volumetric efficiency that leads to higher
capacitance in smaller volumes, i.e. an ongoing miniaturiza-
tion process of these components. The nanosized barium
titanate powder (particle size of 10-25 nm, specific sur-
face area less than 40 m2/g) has been obtained from
unstable precursors by the original technology of rate-
controlled calcination (RCC).
Innovative Aspect and Main Advantages
The innovative aspect of this technology concerns cal-
cination procedure of doped precursor. The precursor is
decomposed under rate-controlled conditions to obtain
the doped nanosized barium titanate. Normally the RCC
proceeds under non-isothermal conditions with variable
heating rate, which is a function of chemical transforma-
tion rate. The feedback established between transforma-
tion degree and instantaneous temperature is the main
innovation and feature of this technique (fig.1).
Fig.1 The scheme of rate-controlled calcinations.
The RCC calcination regime of heating results in smallest
particle sizes of 20-25 nm shown here in Figs. 2, 3.
Areas of Application
Nano BaTiO3 powder and nanograins ceramics is of
highest interest for such industrial applications as mul-
tilayer capacitors. The segment of market of ceramic
multilayer capacitors is around $6 billion. The main
customer is the electronics industry covering medical,
consumer, telecommunication, computing, automobile,
and military etc. The miniaturization of electronic de-
vices is actual now: the trends are thinner active layers,
better dispersion, and finer dielectric particles; present
state-of-the-art product has particles ~ 100 nm and lay-
ers of a few microns. Today’s industry uses BaTiO3
powders doped with 10-15% CaZrO3, CaTiO3, Dy2O3,
MnO to produce the X7R or Y5V series of dielectric
layers. Usually, particle size of both admixed dopants
and BaTiO3 is the same, around 100-200 nm. Future
trends require much smaller particles ~20 nm, much
thinner layers 0.2-0.5 micron to increase markedly the
specific capacity. The revolutionary solution is 100 nm
thick ceramics requires particles of 10-15 nm in size
giving after sintering the grains of 40-50 nm in size i.e.
on the edge of ferroelectricity.
Nanoscale barium titanate powder is also attractive for
manufacturing of nanocomposites with polymer matrix.
These nanocomposites are considered prospective for
attenuators, sensors, transformers and other applica-
tions.
(a) (b)
Fig.2 Barium titanate particle size distribution after RCC:
differential curve (a) and tabulated values (b).
Fig. 3 HRTEM image of
as-prepared barium titan-
ate nanopowder
Stage of Development
We designed and assembled the pilot rotary-tube furnace,
equipped it by the system of gas and temperature control.
This furnace allows transferring the RCC from laboratory
to pilot installment due to temperature gradient along the
furnace. The projected annual yield of Nanosize barium
titanate powder from this furnace is 27-30 t (Fig.4).
Fig. 4 The pilot rotary tube furnace for RCC technology
Contact Details
Contact person: Andrey V. Ragulya
Frantsevich Institute for Problems in Materials Science
Address: Kiev-680,
3, Krzhizhanovsky.,
departament Nanoceramics and Nanocomposites
Tel: (380-44) 424-7435
Fax: (380-44) 424-2131
E-mail: ragulya@ipms.kiev.ua
Web-site: www.materials.kiev.ua
IPMS,
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