1Piezoelectric Materials

Name :- Jairaj Burad

Roll No. :- 514005

Class :- ME (Structures) 1st Sem

Subject :- Mechanics of Modern Materials

Guided by :- Mr. M.V. Bhogone Sir

2Contents Introduction

History

Direct & Inverse Piezoelectric Effect

Properties

Examples of Piezoelectric Materials

Crystal Structure And Dipole Movements

Advantages & Disadvantages

Applications

Conclusion

3Introduction

The term Piezoelectricity was proposed by Hankel.

The word “piezo” originates from a Greek word “piezein” which means “to press”.

Thus Piezoelectricity means electricity generated form pressure. The Phenomenon is called Piezoelectric Effect.

Therefore the materials which show Piezoelectric effect are called Piezoelectric materials.

For Eg. :- zinc blende, sodium chlorate, boracites, tourmaline, quartz, calamine, topaz, tartaric acid, cane sugar, and Rochelle salt.

Piezo Electricity Piezoelectricity

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5History Piezoelectric Effect was first observed by Carl Linaeus and

Franz Aepinus in the mid-1800s, but it was not truly understood until it was demonstrated by French physicists & brothers Pierre and Jacques Curie.

It was observed in an experimental demonstration that some crystals when subjected to pressure show some Electric charges.

The amount of charges is proportional to the applied pressure.

Pierre Curie

Jaques Curie

6 The converse effect was mathematically derived by Gabriel Lippman

in 1881 using fundamental thermodynamic principles and was later experimentally confirmed by the Curies.

The first applications were made during World War I with piezoelectric ultrasonic transducers in. In 1917 Paul Langevin developed a device to detect other sonar objects under water.

The next important stage was the discovery of Ferroelectricity.

The first known Ferroelectric material was Rochelle Salt.

Unfortunately, Rochelle salt loses its ferroelectric properties if the composition is slightly changed, which made it rather unattractive for industrial applications.

During World War II, research groups discovered that certainceramic materials exhibited dielectric constants up to 100 times higher than common cut crystals.

7Direct & Inverse Piezoelectric Effect

Direct Piezoelectric Effect :-

The direct piezoelectric effect is that these materials, when subjected to mechanical stress, generate an electric charge proportional to that stress.

Inverse Piezoelectric Effect :-

The inverse piezoelectric effect is that these materials become strained when an electric field is applied, the strain again being proportional to the applied field.

8Direct Piezoelectric Effect : Generator

Compression Effect: Decrease in volume and it has a voltage with the same polarity as the material

TensionEffect: Increase in volume and it has a voltage with opposite polarity as the material

9Inverse Piezoelectric Effect

If the applied voltage has the same polarity then the material expands.

If the applied voltage has the opposite polarity then the material contracts.

10Properties Piezoelectric materials are being more and more studied as they

turn out to be very unusual materials with very specific and interesting properties.

It has a high value of the dielectric constant.

These materials have the ability to produce electrical energy from mechanical energy, for example they can convert mechanical behavior like vibrations into electricity.

These materials could be used as power generators, the amount of energy produced is still very low, hence the necessity to optimize them.

The piezoelectric ceramics are highly brittle and they have better electromechanical properties when compared to the piezoelectric polymers.

11Examples Of Piezolelectric Materials

Natural Synthetic

Quartz Lead Zirconate Titanate (PZT)

Rochelle Salt Zinc Oxide (ZnO)

Topaz Barium Titanate (BaTiO3)

Sucrose Gallium Orthophosphate (GaPO4)

Tendon Potassium Niobate (KNbO3)

Silk Lead Titanate (PbTiO3)

Enamel Litium Tantalate (LiTaO3)

Dentin Langasite (L3Ga5Sio14)

DNA Sodium Tungstate (Na2WO3)

12Crystal Structure and Dipole Moments

A traditional piezoelectric ceramic is a mass of perovskite crystals. Each crystal consists of a small tetravalent metal ion, usually titanium or zirconium, in a lattice of larger divalent metal ions, usually lead or barium, and O2- ions

At temperatures below the Curie point, however, each crystal has tetragonal or rhombohedral symmetry and a dipole moment. Above the Curie point each perovskite crystal in the fired ceramic element exhibits a cubic symmetry with no dipole moment.

13Crystal Structure of Piezoelectric Ceramics & Quartz

14Advantages & Disadvantages

Advantages Disadvantages

Unaffected by external electromagnetic fields

They cannot be used for truly static measurements

Pollution free Can pick up stray voltages in connecting wires

Low maintenance Crystal is prone to crack if overstressed

Easy replacement May get affected by long use at high temperatures

15Applications

Sonic & Ultrasonic Applications

Pressure Applications

Consumer Electronics Applications

Motor Applications

Civil Engineering Applications

16Sonic and Ultrasonic Applications

Sonar with Ultrasonic time-domain reflectometers. Materials testing to detect flaws inside cast metals and stone

objects as well as measure elasticity or viscosity in gases and liquids.

Compact sensitive microphones and guitar pickups. Loudspeakers.

17Sonar Microphones

Guitar Pickups Loudspeakers

18Pressure Applications

Transient pressure measurement to study explosives, internal combustion engines (knock sensors), and any other vibrations, accelerations, or impacts.

Piezoelectric microbalances are used as very sensitive chemical and biological sensors.

Transducers are used in electronic drum pads to detect the impact of the drummer's sticks.

Energy Harvesting from impact on the ground. Atomic force and scanning tunneling microscopes. Electric igniters and cigarette lighters. Installed in tennis rackets to reduce the shock waves produced

when player hits the ball

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Drumpads Tennis Racket

Cigarette lighters

20Consumer Electronics Applications

Quartz crystals resonators as frequency stabilizers for oscillators in all computers.

Phonograph pick-ups Accelerometers: In a piezoelectric accelerometer a mass is

attached to a spring that is attached to a piezoelectric crystal. When subjected to vibration the mass compresses and stretches the piezo electric crystal.

21Quartz Crystal Resonators Accelerometer

Phonograph Pickups

22Motor Applications

Piezoelectric elements can be used in laser mirror alignment, where their ability to move a large mass (the mirror mount) over microscopic distances is exploited. By electronically vibrating the mirror it gives the light reflected off it a Doppler shift to fine tune the laser's frequency.

The piezo motor is viewed as a high-precision replacement for the stepper motor.

Traveling-wave motors used for auto-focus in cameras.

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Piezo motor Travelling wave motor

24Civil Engineering Applications

Tuned Mass Damper

Actuators on Multi-Span Beams

Tuned Mass Damper Actuator

25Conclusion

Piezoelectric materials are a revolutionary source for “GREEN ENERGY”

Flexible piezoelectric materials are attractive for power harvesting applications because of their ability to withstand large amount of strain.

Converts the ambient vibration energy surrounding them into electric energy.

Electrical energy can then be used to power other devices or stored for later use.

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