Difference Between Piezoelectric Pyroelectric and Ferroelectric

The key difference between piezoelectric pyroelectric and ferroelectric is that the piezoelectric effect is the generation of a surface charge in response to the application of external stress to a material but, the pyroelectric effect is the change in the spontaneous polarization of a material in response to a change in temperature. Whereas, the ferroelectric effect is a change in the surface charge in response to the change in the spontaneous polarization.

Piezoelectric, pyroelectric and ferroelectric are three terms we use to describe the electrical properties of solid materials. These three effects are different from each other according to the responses they display based on the changes made in their other properties.

CONTENTS

1. Overview and Key Difference
2. What is Piezoelectric 
3. What is Pyroelectric 
4. What is Ferroelectric 
5. Piezoelectric vs Pyroelectric vs Ferroelectric in Tabular Form
6. Summary

What is Piezoelectric?

Piezoelectric refers to the property of certain solid materials where these materials can accumulate the electric charge upon the application of mechanical stress. In other words, it refers to the electricity resulting from pressure and latent heat. This term originates from Greek, where piezin means squeeze or press and elektron means amber (an early source of electric charge). This property is named piezoelectricity, and the materials showing this property include crystals, certain ceramics, and biological matter such as bones, DNA, and various proteins.

Typically, the piezoelectric effect can lead to the linear electromechanical interaction between the mechanical and electrical states in crystalline materials having no inversion symmetry. Moreover, this effect is reversible as materials that can show piezoelectric effect can also exhibit the reverse of the effect (it is the generation of a mechanical strain that comes from an applied electrical field).

The nature of the piezoelectric effect is closely similar to that of the electric dipole moment in solids. We can easily calculate dipole density or polarization by summing up the dipole moments per volume of the crystallographic unit cell. Usually, neighboring dipoles tend to align in regions named Weiss domains. This process of alignment is named poling where a strong electric field is applied across the materials at elevated temperatures. However, all piezoelectric materials can not be poled.

What is Pyroelectric?

Pyroelectric means the property of certain crystals has a large electric field due to natural electrical polarization. In other words, it is the ability of certain solids to generate a temporary voltage upon heating or cooling. This term originates from the Greek meaning; pyr means “fire” and “electricity.” Changes in temperature conditions can modify the positions of the atoms within the crystal structure slightly, and it changes the material’s polarization. This change in polarization can give rise to a voltage across the crystal. However, the piezoelectric field that once builds slowly disappears due to leakage current. This leakage occurs due to the movement of electrons through the crystal, movement of ions through the air, and current leaking through a voltmeter that is attached across the crystal.

Pyroelectric effect occurs due to electrical and thermal energy states that do not produce a kinetic energy value. In contrast, piezoelectric effect occurs due to kinetic energy and electrical energy that does not produce heat. Pyroelectric materials are hard and crystals. But there can be some soft materials as well that are made through the use of electrets.

What is Ferroelectric?

Ferroelectric refers to the property of certain materials having a spontaneous electric polarization that is reversible through the application of external electric fields. Usually, all ferroelectric materials are pyroelectric, but it has an additional property of reversible natural electrical polarization. The term ferroelectric comes from ferromagnetism, which was discovered before the discovery of ferroelectricity.

This type of material is useful in making capacitors because of their nonlinear nature. Typically, these capacitors contain a pair of electrodes that sandwich a layer of ferroelectric material. Moreover, the spontaneous polarization of ferroelectric materials implies a hysteresis effect where we can use it in memory function. In addition, ferroelectric capacitors are useful in making ferroelectric RAM.

What is the Difference Between Piezoelectric Pyroelectric and Ferroelectric?

The terms piezoelectric, pyroelectric, and ferroelectric effect refer to the electrical properties of solid materials. The key difference between piezoelectric pyroelectric and ferroelectric is that the piezoelectric effect is the generation of a surface charge in response to the application of external stress to a material. Meanwhile, the pyroelectric effect is the change in the spontaneous polarization of a material in response to a change in temperature. Whereas, the ferroelectric effect is the change in the spontaneous polarization which results in a change in the surface charge.

The following infographic presents the differences between piezoelectric pyroelectric and ferroelectric in tabular form for side by side comparison.

Summary – Piezoelectric vs Pyroelectric vs Ferroelectric

The piezoelectric effect is the generation of a surface charge in response to the application of external stress to the material, while the pyroelectric effect is the change in the spontaneous polarization of a material in response to a change in temperature. The ferroelectric effect is a change in the surface charge in response to the change in spontaneous polarization. Thus, this is the key difference between piezoelectric pyroelectric and ferroelectric.

Reference:

1. “How Piezoelectricity Works.” Eagle Blog.

Image Courtesy:

1. “SchemaPiezo” By Tizeff – Template:Own (CC BY-SA 3.0) via Commons Wikimedia
2. “Pyrosensor” By Nicolas Kruse – Self-photographed (Public Domain) via Commons Wikimedia