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1
Synthesis of Ferroelectric Materials by
Mechanochemically Assisted Methods
The synthesis of powdered-ferroelectric oxides is
classically carried out via solid-state routes
that involve high temperatures and long times of
reaction, implying a possible loss of
stoichiometry and uncontrolled particles sizes.
Ceramics obtained from these powders often cannot
be sintered to full dense materials. At the
Instituto de Ciencia de Materiales de Madrid
(CSIC)- Spain, mechanochemically assisted
synthesis methods are used in order to avoid all
these problems. The effects of varying the
milling media, as well as the length of
mechanical treatments and the annealing
temperature are studied.
Mechanical activation devices
Materials under current study I Layered
perovskites a Aurivillius phases
Bi2An-1BnO3n3 n1 Bi2VO5? Bi2WO6
Bi2MoO6 n2 Bi3TiNbO9 Bi2SrNb2O9
n3 Bi4Ti3O12 n?4
Bi4Srn-3TinO3n3 Bin1Ti4Fen-3O3n3 b
Ruddlesden-Popper phase Srn1TinO3n1 II
Three-dimensional perovskites ANbO3
(ALi, Na) ATiO3 (ASr, Ba) PZN-PT
Results of mechanical treatments

• Vibrating mill
• Amorphous powders with around 100-200 nm in
  particle size.
• Evidence of mechanosynthesis, i.e. the synthesis
  of the final products, is found in some n1
  Aurivillius phases and three-dimensional
  perovskites.

SEM micrograph of a mixture of 2Bi2O33TiO2
mechanically treated in a vibrating mill for 168h.
XRD recording of a mixture of 2Bi2O33TiO2
mechanically treated in a vibrating mill for
different times.
XRD recording of a mixture of BaO2TiO3
mechanically treated in a planetary mill for
different times.
Planetary mill Mechanosynthesized crystalline
powders can be obtained after short mechanical
treatments.
Both textured and isotropic ceramics can be
obtained by hot-pressing and natural sintering
(i.e., single thermal treatment in which
synthesis, grain growth and sintering takes
place), respectively, when mechanochemically
activated precursors are used. The dielectric
and piezoelectric properties of these ceramics
are much improved.
Selected References 1 A. Castro et al. J. Mater.
Chem. 9, 1313-1317 (1999). 2 A. Castro et al.
J. Mater. Chem. 10, 767-771 (2000). 3 L. Pardo
et al. Acta Materialia 48, 2421-2428 (2000). 4
J.G. Lisoni et al. Chem. Mater. 13, 2084-2091
(2001). 5 A. Moure et al. J. Eur. Ceram. Soc.
21, 1399-1402 (2001). 6 T. Hungría et al. Chem.
Mater. 14, 1747-1754 (2002).
Contact person Dr. A. Castro Instituto de
Ciencia de Materiales de Madrid.
CSIC. Cantoblanco. 28049 Madrid. Spain E-mail
acastro_at_icmm.csic.es