Biomedical Engineering Reference
In-Depth Information
a more compact structure. h rough Ti substitution, the dielectric prop-
erty was enhanced and leakage conduction was reduced [52]. h e analysis
of the crystal structure of polycrystalline ceramic samples of Co-doped
BiFeO
3
was done by Yu
et al.
[53]. h ey measured the ferroelectricity of the
samples by hysteresis loop, but the samples did not give a perfect ferroelec-
tric loop. However, on Co substitution, the leakage current was quite large,
which implied that the Co substitution had no ef ect on the improvement
of ferroelectricity in samples. A detailed investigation on the ef ect of Sm
doping on the structural, thermal, electrical and magnetic properties was
given by Nalwa
et al.
[54]. h ey found that Sm-doped samples exhibited
higher magnetization and higher leakage current density than undoped
samples. Ba-substituted BiFeO
3
samples exhibited magnetic, ferroelectric
properties and magnetoelctric ef ect at room temperature [55].
h e well saturated hysteresis loops in P-E characteristics were observed
in the La and Ni codoped BiFeO
3
. h e X-ray dif raction analysis revealed
that the obtained i lms were rhombohedrally distorted perovskite structure
[56]. Some research groups investigated and prepared the solid solution of
BiFeO
3
with other perovskite-type ferroelectric materials such as BaTiO
3
,
PbTiO
3
and PrFeO
3
[57-59]. Pandey
et al.
and others found that the cou-
pling of magnetic and electric order parameters can be studied directly
by measuring the change in polarization induced by an external magnetic
i eld or by measuring changes in the magnetization by an applied electric
i eld in solid solution 0.9BiFeO
3
-0.1BaTiO
3
[60, 61].
13.2
Synthesis of Materials
A variety of methods have been developed for the preparation of single
crystal, thin i lm, nanoparticle, nanotube, polycrystalline ceramics, etc.
h e methodology is concerned with the development of proposed mate-
rial in its pure and substituted form with suitable doping, so that these
materials could be tailored in their desired shape, size and character-
istics. h e multiferroic compounds exhibit ferroelectric and ferromag-
netic properties simultaneously. Although bismuth ferrite (BiFeO
3
) has
been the focus of several researchers, the main problem still concerns
the dii culties in preparing the pure as well as substituted compounds
in ceramic form. Potential applications of BiFeO
3
in memory devices,
in sensors and in satellite communication are strongly restricted due
to leakage current which has been attributed to the presence of addi-
tional phases like bismuth oxide and iron oxide, as well as defects and
non-stoichiometry.
