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The current method for piezocomposite production is the dice-and-fill technique, which consists in cutting two sets of grooves in a block of piezoceramic at right angles each other, then a polymer is cast into these grooves and the solid ceramic base is ground off. Polishing and poling are the following steps in order to achieve the final thickness and properties. This method is expensive, time consuming and size limited.

As an alternative for the dice-and-fill technique, continuos green fibers obtained by the modified viscous-suspension-spinning process, can be bundled into a cottonball-like shape, then burned and sintered. The sintered bundle impregnated with epoxy resin can be sliced into discs and then polarized. Recent results have yielded 1-3 type composites with excellent piezoelectric properties.

On the other hand, an innovative process has been developed for Sr 2 (Nb 0.5 Ta 0.5 ) 2 O 7 /PVDF composites, in this new fabrication method, appropriate amounts of oxides are mixed, pressed and sintered. The porous resulting material is subsequently infiltrated with PVDF solution and then poled. This new method for composites preparation is simple and offers a lead-free alternative smart material.

Another kind of piezocomposites can be achieved by spinning films of piezoceramic onto metal alloys, such as TiNi. The resulting materials is a hybrid composite that can utilize the different active and adaptive properties of the individual bulk materials. Due to the shape memory nature of TiNi, a possible application for this new heterostructures could be smart active damping of mechanical vibrations. DC sputtering and spin coating are the techniques necessary for the smart thin film TiNi/piezoelectric heterostructures fabrication. However, eventhough the films had a fine grain structure and high mechanical qualities, the ferroelectric properties were poor compared to literature values.

In the future, the properties of piezocomposites will be tailored, by varying the ceramic, the polymer and their relative proportions. Adjustments in the material properties will lead to fulfillment of the requirements for a particular device. [link] shows a comparison among piezoelectric ceramics, polymers and composites parameters where Z is the impedance, ε t 33 is the dielectrical constant, and ρ is the density.

Parameter ranges for piezoelectric ceramics, polymers and composites.
Material parameter Piezoceramics Piezopolymers Piezocomposites
k t (%) 45 - 55 20 - 30 60 - 75
Z (10 6 Rayls) 20 - 30 1.5 - 4 4 - 20
ε t 33 0 200 - 5000 ~10 50 - 2500
tan γ (%) <1 1.5 - 5 <1
Q m 10 - 1000 5 - 10 2 - 50
ρ (10 3 kg/m 3 ) 5.5 - 8 1 - 2 2 - 5

Piezoelectric coatings.

Many potential applications exist which require film thickness of 1 to 30 μm. Some examples of these macroscopic devices include ultrasonic high frequency transducers, fiber optic modulators and for self controlled vibrational damping systems.

ZnO and PZT have been used for piezoelectric fiber optic phase modulators fabrication. The piezoelectric materials have been sputter deposited using dc magnetron source and multimagnetron sputtering systems. Coatings of 6 µm thick of ZnO and 0.5 µm of PZT are possible to achieve using these systems. However, thickness variation of approximately 15% occurs between the center and the end of ZnO coatings, results on affected modulation performance. Although PZT coatings achieved by sputtering posses uniformity and do not exhibit cracking, the PZT is only partially crystallized and it is actually a composite structure consisting of crystalline and amorphous material, diminishing the piezoelectric properties.

Sol-gel technique for thick PZT films have been developed. It is now possible to fabricate PZT sol-gel films of up to 60 µm. The electrical and piezoelectrical properties of the thick films reported are comparable with ceramic PZT.

Piezoelectric polymer coatings for high-frequency fiber-optic modulators have been also investigated. Commercial vinylidene fluoride and tetrafluoroethylene copolymer has been used. The advantage of using polymer coatings is that the polymer jacket (coating) can be easily obtained by melt extrusion on a single-mode fiber. Thus, uniformity is easily achieved and surface roughness is not present. Furthermore, if annealing of the polymer is made prior poling, a high degree of crystallinity is enhanced, leading to better piezoelectric properties.


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Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Chemistry of electronic materials. OpenStax CNX. Aug 09, 2011 Download for free at http://cnx.org/content/col10719/1.9
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