A piezoelectric display is a display – such as on a mobile display – that can harden protectively when the device is turned off and soften into a touchscreen that, when pressed, can be depressed. In other words, it is a display that can change shape or texture based on whether it is on or off. While it has only been researched in previous years, it is suggested that this technology will make it to the forefront of mobile devices in the next year as well as future years.

How Does a Piezoelectric Display Work?

Piezoelectric display works because of the ability of some materials to create some sort of an electric field when mechanical stress is applied to it. This creates a change in polarization density within the volume of the material. Once the electric field is generated due to the applied stress, a voltage spreads across the entire material. In other words, a piezoelectric display works in such a way that when someone presses down on the screen, it causes the material inside it to create an electric field. This electric field allows the material, due to changes in polarity, to depress or not depress.

What are Piezoelectric Materials?

A material that exhibits piezoelectric properties is one that creates an electric field when mechanical stress is applied. There are numerous different naturally occuring piezoelectric materials; however, there are also a handlfull of man-made ones that demonstrate the same properties. They are broken up into separate categories.

Naturally-Occuriring CrystalsPiezoelectric Display

  • Berlinite: This is an incredibly rare phosphate mineral. Structurally, it is indentical to quarts; however, chemically, it has its differences.
  • Cane Sugar
  • Quarts
  • Rochelle Salt: It's chemical name is Potassium sodium tartrate and is a double salt. A double salt is a salt that has either more than one cation or more than one anion. The cation is the positively charged ion; the anion is the negatively charged ion. It's through these charged ions that ionic bonds are formed. Positive and negative attach.
  • Topax

Other Natural Materials

  • Bone: It has been found that when a bone is completely dried out, it can exhibit some form of piezoelectric properties. This is due to the collagen inside of it because it exhibits polar uniaxial orientation of the molecular dipoles in its structure.
  • Tendon
  • Silk
  • Enamel
  • Dentin

Man-Made Crystals

  • Gallium orthophosphate: This is a man-made crystal that shares properties similar to quarts.
  • Langasite: Similar to the previous, this is a quarts analogic crystal.

Man-Made Ceramics

  • Lithium niobate
  • Lithium tantalate
  • Barium titanate: First piezoelectric ceramic discovered.
  • Lead zirconate titanate: Known as PZT, it is the most common piezoelectric cermaic used today.
  • Sodium tungstate

Because of a growing concern about the toxicity found in lead, there has been a push for lead-free piezoceramics. In recent years, a handful of these lead-free piezoelectrics have been discovered and created by researchers in the hopes of having a less toxic material. These are:

  • Sodium potassium niobate
  • Basmuth ferrite
  • Sodium niobate