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Piezoelectric crystals

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Leah MacMillan

on 9 December 2013

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Transcript of Piezoelectric crystals

Piezoelectric Crystals
These are crystals that can be used as a transducer and used as a component in various electronic devices.
Where it is found!
These crystals can be found in the earth, examples of this would include quartz or amathist.
How does it work!
Piezoelectricity is when an electric charge gathers in certain solid materials such as crystals, when stress to the object is applied. Electricity is created from directing pressure on the crystal.
Different Crystals
By Leah MacMillan
What it is!
How it is used in Society
The Fields
The Crystal Properties
Piezoelectric crystals are crystals that acquire a charge when they are compressed, twisted or distorted. This creates a transducer effect between mechanical and electric oscillations.
Quartz are one example of a crystal that has acquired this characteristic and it is very stable in doing so. Quartz are used as watch crystals, for precise frequency reference crystals and for radio transmitters.
Rochelle salt can produce a large voltage upon compression. These salts where used in the early crystal microphones.
The effect is considered to be linear in the electromechanical interaction of the crystalline materials. There is no possible inversion of this, as it is a reversible process.
These crystals are able to generate piezoelectricity when they are in their static structure. As the crystal is deformed from the original dimension their static dimension will also change, this is the inverse effect that is used to produce ultra sonic waves.
You can also create this crystals as potassium sodium tartrate. This is called Rochelle salt. It is made form sodium carbonate and potassium pitartrate. This crystal was one of the first known piezoelectric crystals
This video demonstrates how to make a piezoelectric crystal, as well as how to allow the it to have a flow of potential energy.
The crystals where first discovered to generate an electric potential energy in response to a temperature change.
All images that where used are obtained through the Prezi software are from google images and are for public use, not encroaching on any copy right laws.
Direct piezoelectricity of some substances, like quartz, can generate potential differences of thousands of volts.
Barbeque lighters operate by pressing a button that causes a spring-loaded hammer to hit a piezeolectic crystal, this produces a high enough voltage of electric current to flow across a small spark gap which heats and ignites the gas. This is how many lighters work to ignite different burners.
It is possible to harvest the energy of movement through these crystals. Some public spaces such as train stations or dance floors could be constructed with these crystals so that the impact of people walking, or even the vibration of industry machinery in factories can be harvested by the piezeolectric materials to charge back up power supplies or wireless radios.
A crystal, such as quartz, produces a potential difference across its opposite faces when under mechanical stress.
Piezoelectricity is the inducement of polarization by mechanical deformations. This polarization is the effect of an electrical field. When dealing with a crystal with iconic components there can be symmetrical arrangements. This has three dipole moments that exactly cancel each other out. Yet when some elastic deformation is induced the symmetry is broken and the three dipole moments no longer cancel out. This induces the polarization by mechanical deformation.
Piezoelectricity can be found in certain crystals when they are deformed in certain directions to properly deform the symmetry of the crystal. The crystal symmetry must not have an inversion center to be able to conduct a potential energy. The crystals generally have a relation between the polarization and the deformation of the form.
The mechanical deformation produces the polarization which is the electrical field inside the material. This means that when the crystals are exposed to an electric field they will experience a force and become deformed. The crystal could lengthen or shorten.
Piezoelectricity is found useful in many applications in life. It can detect sound, generate high voltages and electronic frequencies. It can also be used for micro-balances and ultra-fine focusing of scientific instruments, or everyday uses such starting a propane barbeque
Piezoelectric crystals have lead to many developments as they are used in the modern world, in things such as ultrasound machines that have helped the medical community. The word piezo is Greek for "push" and this is how the crystals got their name. This effect of piezoelectricity was first discovered in materials such as crystals by two brothers, Pierre and Jacques Curie when they were 21 and 24 years old in 1880. These brothers made a great contribution to science and have lead the way to some great technology.
Ultra-Sound Machines
Piezoelectric crystals have a very unique propriety that makes them practical in everyday uses. They are practical because they can harness the energy of movement (mechanical energy) and convert it to a more practical energy of electrical potential.
High performance ultra sound machines have piezoelectric crystals at the base of the nose on the machine. This is because the crystals have active polymers, this allows the waves to be continuous through different materials, in this case skin. The crystals have an advantage in these machines over other piezoelectric materials because they are more precise when they are conducting a potential energy and they are able to produce a higher bandwidth. The crystals are also able to adapt to different temperatures.
*Click the video to play the clip!*
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