Bismuth Ferrite review
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Transcript of Bismuth Ferrite review
Bismuth Ferrite
The potential of future electronic memory devices are at its
twilight of booming into a new set of generation of memory chips.
Instead of having the memory devices of which are as big as tens
of nanometer, which is what our today technology’s advanced
system offers, comes a memory device shrinking to one or two
nanometer. If only one can synthesize a way to gasp into his
hands the controls of how to separate those regions that have
different electric, magnetic and other properties this would be
possible.
Bismuth ferrite is a compound of bismuth, iron and oxygen—
BiFeO3. This compound was discovered to have domain walls never
been seen by scientists of the department of energy at Lawrence
Berkeley National Laboratory of the University of California.
Even though Bismuth ferrite was originally know as an insulator,
this compound was discovered to have different electrical
polarity that conducts electricity at room temperature. In this
review, I will focus primarily on the synthesis, physical and
chemical properties, industry use and its effect upon disposal to
the environment of Bismuth Ferrite.
Chemical and physical properties
Bismuth ferrite, being an inorganic chemical compound, has
perovskite structure ( in which planes of heavy atoms, bismuth
for this compound, and oxygen alternates with planes of lighter
atoms, Iron for this compound, and oxygen atoms) and is said to
be one of the most promising multiferroic materials that exhibits
multiferroic properties at room temperature. At room temperature,
BiFeO3 is classified as rhombohedral that belongs to group R3c.
It is synthesize in thin film and in bulk and it temperatures—
antiferrmagnetic Neel and ferroelectric Curie—are well above room
temperature (653 K nd 1100 K, respectively). Its polarization
occurs with a magnitude of 90-95 µC/cm2 along the pseudocubic 111
direction. Its walls are oriented along two different
crystallographic planes, meaning it can be separated with 109-
degree, 71-degree, or 180-degree differences in the direction of
the polarization. Bismuth ferrite films contains ferroelectric
sphere that is between 5 to 10 micrometers. It exhibits week
magnetism at room temperature because of the spiral magnetic spin
cycloid with a periodicity of 62 nm.
Synthesis/preparation of Bismuth ferrite
In synthesizing this promising alloy, many ways were
developed. The following are just some of the ways on how to
produce Bismuth ferrite:
SOL-GEL TECHNIQUE
A 2:1 ratio of bismuth and iron was prepared from the
starting materials bismuth nitrate and ferric chloride. The
excess bismuth is used to compensate the bismuth evaporated
during high temperature annealing. Bismuth nitrate and ferric
chloride were dissolved in acetic acid and was added with
ethylene glycol that served as a drying control agent to restrict
cracking of the thin films before coat spinning. The solution was
them refluxed for 5 hour.
Figure 1. Flow chart of the
synthesis of BiFeO3 .
The precursor was coated on
copper substrate at 3000 rpm for 30
seconds while spinning after it was
cooled down to room temperature.
For thicker film, the process was
repeated. After the process, the film
was kept exposed for 1 hour for gel film to form via hydrolysis
Figure 1
and polymerization. The film was dried via heat treatment at a
temperature of 300o C for 2 hours. The Crystallization,
densification and microstructure of the films were then examined.
SUPERFACTANT ASSISTED AUTOCOMBUSTION SYNTHESIS
Bismuth ferrite powder was
synthesized by a solution
evaporation route. A 0.25 M Bi(NO3)3
and a 0.25 M Fe(NO3)3 was prepared by
dissolving it in dilute nitric acid.
The two solutions were mixed in a
beaker. A 0.1 mole ratio of glycine
was added to the solution above with
respect to nitrate. The supernatants
Triton X, and ALS (ammonium lauryl
sulfate) were added to the solution
with a mole ratio of 0.05
with respect to the metals. The solution was then heated on a hot
plate with continuous stirring until it reaches its boiling
temperature such time that all liquid have already evaporated. A
brown fume that evolves during the process was obtained at the
bottom of the beaker. The powder was than calcined at 500oC and
550oC. the crystalline size of the powder was then computed using
the Scherrer formula.
Figure 2
Figure 2. Flow chart of supernatant assisted autocombustion
synthesis.
SUPER CRITICAL HYDROTHERMAL SYNTHESIS
The equal mole amount (0.003 mol) of Bi(NO3)3·5H2O and
Fe(NO3)3.9H2O was weighted. Then, Bi(NO3)3.5H2O and Fe(NO3)3.9H2O
was dissolved in 250 ml deionized water and was heated until
homogenized. It was than transferred to a reactor vessel. A
stainless steel 316 with 180 mL volume bath type reactor was used
and was heated using an electrical heater.
The hydrothermal reaction was performed in the reactor
vessel at 500o C for 2 hours. After then, the reactor vessel was
reduced to stop the reaction with cold water so that the product
will be collected through washing the reactor with deionized
water and cetrifugate to remove the reagent that didn’t reacted.
Then the BiFeO nanoparticles were dreid at 40o C for 24 hours.
The identity of the synthesized nanoparticled was then X-
rayed for diffraction measurements. The size and the shape of the
obtained nanoparticled was then studied using transmission
electron microscopy.
Important use in the industry
In the past studies, bismuth ferrite has proven itself for
its effective and applications to the industry. Bismuth ferrite
was used as high tech magnetic tapes, used for its
superconductivity, used in environmental engineering; and
finally, is used to enhance spontaneous magnetization. But for
this review, I will focus on the new discovered application of
bismuth ferrite--nanoscale shape-memory oxide.
Bismuth ferrite is a compound of bismuth, iron and oxygen.
This multiferroic compound has been studied thoroughly in recent
years by many scientists. As bismuth ferrite, being a
multiferroic alloy, displays both ferromagnetic and ferroelectric
properties, meaning it responds to applications of magnetic field
or external electric. In this latest study by the scientists of
the University of California in Berkley they were able to
introduce an elastic-like phase transition into bismuth ferrite
by means of electric field.
Bismuth ferrite's application to the electric field allowed
them to develop a phase transformation to be achieve that is
reversible even without assistance of an external stress recovery
said Ramesh of the University of California in Berkley.
This new discovery of the shape-memory alloys claimed to be
the champion for elasticity and is primed to take over the shape
memory apps to a whole new level---which is shrinking it to
nanoscale. Researchers in Berkley laboratory have discovered a
way to introduce recoverable strain into bismuth ferrite up to
14%.
This is larger than any shape-memory effect observed in any
metals for now. This discovery opens new door to for the
application of many fields such as that in medical, energy, and
specially electronics.
According to Jinxing Zhang this bismuth ferrite they newly
developed displays amazing features including being stable even
when reduced to nanometer compared to other shape-memory alloys.
One more feature is that its responses are fast due the
electrical field needed to activate shape-memory alloy rather
than the primitive way of using thermal fields.
A shape-memory effect is when a solid material grows back to
its original shape after being deformed after stress is applied
is an ability of a metal to be elastic. In the past, this has
always been involved with heating. Nickel-titanium or "nitinol”
alloy is a shape-memory alloy that has a great use to those that
are in the field of medicine. It is used intents for angioplasty
and in medical joints. This memory effect of alloy has also have
a great impact for non-medical fields. An example is the
actuators in smart materials and in Microelectro-Mechanical
Systems (MEMS). But as scientist try to achieve nano-scale size
of this shape-memory alloys, various problems and instabilities
arises such as micro-cracking and oxidation. But with the new
study on bismuth ferrite, scientists of Berkley Lab's materials
Sciences Division of the University of California in Berkley were
able to eliminate surface issues and were able to integrate it
with microelectronics by achieving shape-memory effect to an
oxide material rather than in alloy metals. According to Zhang,
this bismuth ferrite they developed has "ultra-high work function
density during actuation that is almost two orders of magnitude
higher than what a metal alloy can generate." Ramesh also added
that even though aspects like hysteresis, micro-cracking and so
many more needs to be accounted when it will be applied to real
devices, the discovery of bismuth ferrite being able to show
large shape-memory effect only shows that it is not an ordinary
material. This alloy has great potentials that it can be use in
the future in nanoelectromechanical devices and other state-of-
the-art nanosystems.
References:
Researchers Discover Nanoscale Shape-memory Oxide. (n.d.). In PCB
Design 007. Retrieved December 20, 2013, from
http://www.pcbdesign007.com/pages/zone.cgi?
a=96945&artpg=1&topic=0
Physicists observe new magnetic state of bismuth ferrite (n.d.).
In Phys.org. Retrieved December 20, 2013, from
http://phys.org/news/2013-05-physicists-magnetic-state-bismuth-
ferrite.html#inlRlv
Remembrances of Things Past: Berkeley Lab Researchers Discover
Nanoscale Shape-Memory Oxide (n.d.). In Hispanicbusiness.
Retrieved December 20, 2013, from
http://www.hispanicbusiness.com/2013/12/3/remembrances_of_things_
past_berkeley_lab.htm
Researchers take the lead out of piezoelectrics (n.d.). In
Phys.org. Retrieved December 20, 2013, from
http://phys.org/news177340310.html
Hu, Y., Fei, L., Zhang, Y., Yuan, J., Wang, Y., and Gu, H.,
(2010). Synthesis of Bismuth Ferrite Nanoparticles via a Wet
Chemical Route at Low Temperature. Hindawi Publishing
Incorporated, 2011(2011), 6 pages. Retrieved from
http://www.hindawi.com/journals/jnm/2011/797639/
Haneberg, D. H. (2011). A Finite-Size Study on Samarium-
Substituted Bismuth Ferrite: Multiferroic and Lead-Free
Piezoelectric Materials. Abstract retrieved from NTNU.
Shurygina V.Yu., Zhereb V.P., Skorikov V.M. (2013). MECHANISM OF
SOLID STATE SYNTHESIS OF BISMUTH FERRITE BI25FEO39. Abstract from
Digital scientific journal
PDF:
Bismuth ferrite nanoparticles formation via a supercritical
hydrothermal synthesis method (2012) by J. Karimi, A., and
Golzary, C
Synthesis and Properties of Bismuth Ferrite Multiferroic
Nanoflowers (2000’s) by Chybczynska, K., Ławniczak, P., Hilczer,
B., Łeska, B., Pankiewicz, R., Pietraszko, A., Kepinski, L.,
Kałuski, T., Cieluch, P., Matelski F., and Andrzejewski, B.