A joint research group of Professor Atsushi Muramatsu, Assistant
Professor Kiyoshi Kanie at IMRAM, Tohoku University, and Confidential, a
manufacturer of materials synthesis, sintered compact, and device
implementation, newly developed an enormous amount of solution phase
synthesis. The new method uses a technology to precisely control sizes
and shapes of alkali niobate metal salt particles for piezoceramics that
are used as sensors, ultrasonic vibrators, transformers for liquid
crystal backlight of personal computers, and head parts materials of
inkjet printers.

Most piezoceramics are lead-based such as PZT-based materials, and
lead-based materials include a large amount of hazardous lead oxide. A
demand for developing lead-free piezoceramic materials that can replace
exiting lead-based ones has been increased because of the concern about
environmental pollution caused by lead oxide outflow.

Recently, alkali niobate piezoceramics as lead-free ceramic materials
that are relatively highly piezoelectric have gathered attention. Such
piezoceramics are usually synthesized in a solid-phase method, but it
has been extremely difficult to homogeneously mix raw material powder at
the nano-level, and precisely regulate crystalline sizes and grain
boundaries. Regulating grain boundaries is necessary to improve
piezoceramic properties because grain boundaries have a great effect on
piezoelectric properties and intensity. Materials whose grain boundaries
are not regulated enough may have caused damage to products or property
defects.

On the other hand, the problem is that particles are aggregated, and
uniformly regulating grain diameters and shapes has been impossible in
an existing liquid phase method. Taking the fact into consideration, a
demand for a new mass production method of alkali niobate metal salt
particles has been increased. The new method can prevent particle
agglutination, and regulate grain boundaries or grain diameters. It has
been also expected to develop alkali niobate metal salt fine particles
whose grain sizes and shapes are highly uniform.

The research results shows a possible reproducible synthesis of sodium
niobate potassium salt particles that consist of secondary particles
that have uniform sizes and special shapes by combining sodium and
potassium at a particular rate. Mass synthesis of the particles for
stable supply and sample shipments are getting ready. Preliminary
experimental results found that piezoelectric properties are dynamic to
be devisable, and such particles are at the stage of being used as
piezoceramic materials.

[Contact]
Professor and Assistant Director Atsushi Muramatsu
IMRAM, Tohoku University
Tel: +81 22-217-5163
E-mail: mura@tagen.tohoku.ac.jp