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What is soft and hard PZT?

What is soft and hard PZT?

Last Updated on March 23, 2023 by You Ling

Piezoelectric materials have many types, but the most widely used are based on lead zirconate titanate (PZT), which is divided into two categories: soft and hard piezoelectric materials, also known as soft PZT and hard PZT.


  • What is soft PZT
  • What is hard PZT
  • soft PZT vs hard PZT
  • What are soft piezoelectric materials
  • Applications of Soft Piezoelectric Materials
  • What are hard piezoelectric materials
  • Applications of Soft Piezoelectric Materials
  • How to choose a suitable piezoelectric material



1、What is soft PZT?

Soft PZT is the abbreviation of Soft Piezoelectric Materials

Soft PZT refers to a type of ferroelectric piezoelectric ceramic with high mobility of the dipole or magnetic domain, which indicates polarization and depolarization characteristics. They are suitable for use in piezoelectric actuators and sensors due to their small polarity reversal field strength. Soft PZT materials have the advantage of a large piezoelectric strain constant, moderate dielectric constant, and high coupling factor.


2、What is hard PZT

Hard PZT is the abbreviation of Hard Piezoelectric Materials

Hard PZT materials can withstand high electrical and mechanical stress, and their properties remain almost unchanged under these conditions. They are mainly used in high-power acoustics. The advantages of hard PZT materials are their moderate dielectric constant, large piezoelectric coupling factor, high mechanical quality, and good stability under high mechanical load and large working field strength. They generate little heat internally and have low dielectric loss, making them suitable for sustained use in resonance modes.


3、Soft PZT vs Hard PZT

Soft PZT and hard PZT have opposite characteristics. Soft PZT has a large electromechanical coupling coefficient, large piezoelectric constant, high dielectric constant, high dielectric loss, low mechanical quality factor, and poor linearity. Compared to hard PZT, they produce larger displacements and wider signal bandwidths but exhibit larger hysteresis and are more prone to depolarization or other degradation. The lower Curie point (usually below 300°C) requires the use of soft PZT at lower temperatures. The relatively large dielectric constant and loss factor can limit or eliminate the use of soft PZT in applications requiring high-frequency input and high electric field combinations.


Hard PZT has characteristics opposite to soft PZT, including a Curie point above 300°C, small piezoelectric charge constant, large electromechanical coupling factor, and high mechanical quality factor. They are also more difficult to polarize or depolarize. Although hard PZT is usually more stable than soft PZT, they cannot produce the same magnitude of displacement. Hard PZT can withstand high mechanical loads and high voltages.


Characteristic Soft PZT Hard PZT
Piezoelectric Constants larger smaller
Permittivity higher lower
Dielectric Constants larger smaller
Dielectric Losses higher lower
Electromechanical Coupling Factors larger smaller
Electrical Resistance very high lower
Mechanical Quality Factors low high
Coercive Field low higher
Linearity poor better
Polarization / Depolarization easier more difficult


4、What are the soft piezoelectric materials?

Soft piezoelectric materials mainly include PZT-5A (NAVY TYPE II), PZT-5H (NAVY TYPE VI), PZT-5J (NAVY TYPE V).

Our company’s corresponding products are:



High dielectric constant, large coupling factor, large piezoelectric strain constant, and relatively high Curie temperature.

Piezo ring PZT-5H
Piezo ring PZT-5H

5、Applications of soft piezoelectric materials

The important application areas of soft piezoelectric ceramics include actuators (used for micro-positioning and nano-positioning), traditional vibration detectors, sensors such as ultrasound transmitters and receivers (used for flow or level measurement, target identification or monitoring), as well as audio applications such as sound sensors, microphones, and instrument pickups.


6、What are the hard piezoelectric materials?

Hard piezoelectric materials mainly include PZT-P4 (NAVY TYPE I), PZT-P8 (NAVY TYPE III).

Our company’s corresponding products are:

PZT-40 ,PZT-41 ,PZT-42, PZT-43 ,PZT-43HD, PZT-44, PZT-45, PZT-45HD, PZT-46, PZT-47, PZT-48


Large electromechanical coupling factor, high quality factor, good electromechanical stability, and high compressive strength.

What's PZT-8 datasheet?


7、Applications of hard piezoelectric materials

High-power audio applications particularly benefit from the properties of hard piezoelectric materials. Application areas include ultrasonic cleaning (typically in the kilohertz frequency range), material machining (ultrasonic welding, pressure welding, drilling, etc.), ultrasonic processors (such as for spraying liquid media), medical field (ultrasonic removal of dental plaque, surgical instruments, etc.), and sonar technology.


8、How to choose the appropriate piezoelectric material?

The first and most important factor to consider when choosing a piezoelectric material is its piezoelectric properties. These properties are the measure of a material’s ability to convert mechanical energy into electrical energy and vice versa. Some key piezoelectric properties to consider include the piezoelectric coefficient, dielectric constant, mechanical quality factor, and electromechanical coupling factor. The piezoelectric coefficient is a measure of a material’s ability to convert mechanical energy into electrical energy and vice versa. It is typically measured in units of charge per unit force or voltage per unit strain. Higher piezoelectric coefficients indicate higher efficiency in energy conversion.