Piezoelectric Ceramics Principles And Applications Ebook 16
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Piezoelectric Ceramics: A Comprehensive Guide to Principles and Applications
Piezoelectric ceramics are materials that can convert mechanical stress into electric voltage, or vice versa. They have a wide range of applications in various fields, such as sensors, actuators, transducers, generators, and more. In this article, we will introduce the basic concepts of piezoelectricity and piezoelectric ceramics, as well as some of their common and emerging uses.
What is Piezoelectricity
Piezoelectricity is a phenomenon that occurs when certain materials deform under mechanical stress and produce an electric charge. Conversely, when an electric field is applied to these materials, they change their shape or dimensions. The word piezoelectric comes from the Greek word piezein, which means to squeeze or press.
The piezoelectric effect was discovered in 1880 by Pierre and Jacques Curie, who observed that quartz crystals generated electric voltage when subjected to pressure. Later, it was found that other materials, such as tourmaline, Rochelle salt, and bone, also exhibited piezoelectricity. In 1910, Paul Langevin developed the first piezoelectric transducer for underwater sonar detection.
However, natural piezoelectric materials have limited availability and performance. Therefore, researchers began to develop synthetic piezoelectric materials, such as ceramics and polymers. Piezoelectric ceramics are made by mixing and firing various oxides, such as lead zirconate titanate (PZT), barium titanate (BaTiO3), and lead magnesium niobate (PMN). They have high piezoelectric coefficients, meaning they can produce large electric charges or displacements under small stresses or fields.
How do Piezoelectric Ceramics Work
Piezoelectric ceramics have a crystalline structure that consists of positive and negative ions arranged in a regular pattern. When no external force is applied, the net electric dipole moment of each unit cell is zero, because the positive and negative charges are symmetrically distributed. However, when a mechanical stress is applied, the unit cells deform and the charges shift slightly, creating an electric polarization. This polarization induces an electric potential across the material, which can be measured by electrodes attached to its surface.
Similarly, when an electric field is applied to a piezoelectric ceramic, it causes the unit cells to align with the field direction and change their shape or size. This change in dimension results in a mechanical strain or displacement of the material.
The relationship between the mechanical stress (or strain) and the electric field (or potential) of a piezoelectric material can be described by a set of equations called the piezoelectric equations. These equations depend on the material properties and the direction of the applied force or field. They can be used to calculate the output voltage or displacement of a piezoelectric element for a given input force or field.
What are Some Applications of Piezoelectric Ceramics
Piezoelectric ceramics have many applications in various domains, such as:
Sensors: Piezoelectric sensors can detect changes in pressure, force, acceleration, temperature, or vibration by converting them into electric signals. For example, piezoelectric microphones can capture sound waves; piezoelectric accelerometers can measure motion or shock; piezoelectric pressure sensors can monitor blood pressure or fluid flow; and piezoelectric temperature sensors can measure thermal expansion or contraction.
Actuators: Piezoelectric actuators can produce precise movements or forces by applying electric fields to them. For example, piezoelectric motors can drive mechanical devices; piezoelectric pumps can move fluids; piezoelectric valves can control gas or liquid flow; and piezoelectric injectors can deliver fuel or drugs.
Transducers: Piezoelectric transducers can convert one form of energy into another by using both the direct and inverse piezoelectric effects. For example, piezoelectric speakers can generate sound waves from electric signals; piezoelectric ultrasonic transducers can emit or receive high-frequency waves 061ffe29dd