For the initial experimentations on piezoelectricity, the materials that were used were crystals and introduced the concept piezoelectric effect in the year 1880. With the investigations done on few materials, the two materials those exhibited maximum piezoelectric effect were Rochelle salt and Quartz. In continuity with the investigation done on a piezoelectric material, they exhibited good properties, characteristics, and benefits. And the initial application of these materials was an ultrasonic submarine detector. Based on our requirement and specification, there exist many types in these materials and let’s have an overview of the working nature and examples of piezoelectric materials?
What is Piezoelectric Material?
The materials that exhibit the property of electric current when certain pressure, force or stress is applied. These materials also exhibit an inverse effect which means that with the application of electric current, there will be a slight variation in the shape of the material. Few of the known materials exhibiting piezoelectric properties are quartz crystals, proteins, bones, and ceramic crystals.
Piezoelectric Material Properties
The essential properties exhibited by piezoelectric materials are:
- Dielectric constant value is more
- Few of the areas in some domains have spontaneous polarization
- These materials hold the effect of a hysteresis loop in strain-polarization electric field curves.
- When the temperature is increased, the dielectric constant value also gets increased
- Above the curie point, there will be a disappearance of ferroelectric properties for these materials.
- Ceramic materials show more piezoelectric constant than that of polymers
- Mechanical deformations in ceramic dependent materials are more when compared to that of polymer dependent materials even when the same voltage levels are applied for both.
- As PZT’s have an increased electromechanical coupling coefficient, these can be implemented for the conversion of mechanical pressure to electric energy.
- As there are many classifications of piezoelectric materials, each one of the types has its corresponding properties. For example: for actuator devices, non-hysteretic strain levels and strain coefficient has to be more.
- Off-resonance frequency devices use the property of low dielectric loss.
- Materials having high, low and medium values of dielectric constant are used as Ferro soft piezoelectric materials, whereas dielectric constant values are varied for Ferro hard materials.
- Temperature ranges are more for porous piezoelectric materials
The piezoelectric material constitutive equation describes how factors such as electric field, strain, stress and charge-density displacement relate with each other. It is defined as
S = sE. T + dt. E and D = d. T +єT. E
Where ‘T’ corresponds to the material stress
‘S’ is the strain, ‘D’ is charge-density displacement and ‘E’ is an electric field and ‘d’ is the coupling matrix
The other equations to be considered for piezoelectric materials are
Electromechanical Coupling Factor (k)
K = accumulated mechanical energy/applied electric energy
Piezoelectric Strain Constant (d)
d = x/E
Piezoelectric Voltage Constant (g)
It defines the relationship that exists between the induced electric field and stress which is applied to the material. With the relation P = dX, g can be defined as
g = d/є0
Mechanical Quality Factor (QM)
This defines the intensity of the electromechanical resonance approach and given by
QM = w0/2w
How Piezoelectric Material Works?
Piezoelectric materials function based on the concept of piezoelectricity and there are two operating modes such as:
- Direct piezoelectric effect
- Inverse piezoelectric effect
Direct Piezoelectric Effect
As we are aware that the application of force on a piezoelectric material generates piezoelectricity. This concept can be clearly explained with the below illustration.
When a piezo material is placed in between the two metal plates, they compress the material and these plates accumulate charges and generate a voltage which is termed as piezoelectricity. With this phenomenon, PZE acts as battery thus producing charge. A few of the devices that operate in this mode are hydrophones, a few kinds of sensors, pressure sensors, and microphones.
Please refer to this link to know more about Piezoelectric Transducer MCQs
Inverse Piezoelectric Effect
This effect can be created by the application of electric charge on the piezoelectric material where this creates deformation (compression or expansion) of the material. So here, electric energy is transformed into mechanical energy. This approach assists diodes to develop acoustic sounds like speakers.
The most used materials are:
- Lead zirconate titanate
- Lithium niobate
- Barium titanate
The detailed explanation of piezoelectric material examples are
This material helps to find out underwater submarines. This device makes use of the inverse piezoelectric effect and generates sound waves to detect the objects. Here, the transmitter uses IPZE and produces sound waves, whereas the receiver uses DPZE. It transmits the wave to the signal-handling electronics which again process the reverse sound signal. Through this, the object’s distance is known by the calculation of timing signals.
The operation of actuators is similar to that of the basic operation of the piezoelectric device which causes mechanical deformation. Actuators are employed in video cameras, braille devices, and cellular phones.
Speakers and Buzzers
These devices operate on the mechanism of IPZE where the application of voltage to these devices generates sound. The vibration developed inside the device produces a sound signal and comes out. Alarm clocks are the best examples.
To power-up piezoelectric machines, these drivers are used to transform minimal voltages to maximum voltages. The input is low voltage signals and with the help of amplifiers, the output will be high voltage signals. The circuit diagram is as below:
The advantages/disadvantages of piezoelectric material are as follows:
- These materials are available in any kinds of deformations
- They have robust constructions
- Compact in size
- Shows maximum frequency response
- Minimal phase shift levels
- There will be piezo only a minimal amount of electricity production and there needs to be the installation of other equipment. So piezoelectric materials might not hold the ability to power up modern gadgets.
- Only upon the application of force, the current is produced. When there is no compression, the production of current stops.
- Most of the initial products used to generate piezoelectric materials are poisonous and complicated to operate with.
Applications of Piezoelectric Materials
Piezoelectric materials are extensively applied in a wide range of industries and few of those to be known are
- Employed in the recognition and creation of sonar signals
- Used in biological and chemical kind of sensors
- Used in pressure gauges
- Used for the conversion of an applied voltage to mechanical form
- In fuel injectors
- Atomic pressurized microphones
Even these materials hold extensive applicability in the medical domain, and they are used as
- Blood pressure sensors
1). What is the best piezoelectric material?
PZT which is called as lead zirconate titanate is the best piezoelectric material.
2). What are piezoelectric materials used for?
There is a wide range of utilization of piezoelectric materials like in a sound signal generation, sensors, and actuators.
3). Is piezoelectric AC or DC?
The vibrating piezoelectric material develops alternating voltage.
4). How many watts is a piezoelectric?
There will be an output of 2 amperes when 2 500 watts lamps are connected in series.
5). Who discovered piezoelectricity?
Paul Jacques Curie is the person behind the invention of piezoelectricity in the year 1880.
This article shows an overview of the application, working, advantages, issues, and applications of piezoelectric materials. With the continuous development and progression of these materials shows advanced applications and to be utilized in various domains and industries. Get to know the detailed concept on what are the furthermore applications of piezoelectric materials?