Curie temperature

What is Curie temperature and its influence on piezoelectric ceramics

The Curie temperature of piezoelectric ceramics refers to the phase transition temperature of the piezoelectric material from the ferroelectric phase to the paraelectric degree. For all piezoelectric ceramic products, piezoelectric materials have a critical temperature Tc that is Curie temperature. Piezoelectric ceramics exhibit a ferroelectric phase below the required temperature, and the piezoelectric ceramics are in an orderly state of polarization.

When the temperature exceeds the critical temperature Tc, the piezoelectric ceramic changes from the ferroelectric phase to the paraelectric degree, at this time, the internal electric dipole distance of the piezoelectric ceramic is chaotic and in a state of polarization disorder, which is what we often say that depolarization has occurred.

The closer the piezoelectric ceramic’s temperature is to the Curie temperature, the more significant the change in the performance of the piezoelectric ceramic. Therefore, in the process of using piezoelectric ceramics, it must be used far below the Curie temperature, not higher than half of the Curie temperature.

Piezoelectric ceramics are sintered at the Curie temperature,If the temperature exceeds the Curie temperature, the piezoelectric ceramics will be depolarized. Once depolarized, the piezoelectric effect will disappear, but it can be re-polarized by adding an electric field. Therefore, in using piezoelectric ceramics, keep it below the Curie temperature.

The Curie temperature points of piezoelectric ceramics of different materials are different. Generally, the Curie temperature of low-voltage stacked piezoelectric ceramics is about 150-200°C; the local weather of low-voltage and high-temperature piezoelectric ceramics is about 340°C, and the Curie temperature of high-voltage piezoelectric ceramics is about 215-340°C.

Common problems with Curie temperature

  1. Can piezoelectric ceramics still usually work if the temperature exceeds the Curie temperature?
    When the piezoelectric ceramic’s temperature exceeds its Curie temperature, the piezoelectric ceramic will be depolarized and can no longer work typically.
  2. Can’t depolarized piezoelectric ceramics be used?
    Of course not. Piezoelectric ceramics depolarized due to high temperature can be repolarized by applying voltage.
  3. How to judge the safe use temperature based on the Curie temperature?
    Generally, we recommend using a temperature of about half of the Curie temperature to ensure the long-term stable performance of piezoelectric ceramics.
  4. Is it possible that two piezoelectric materials with different Curie temperatures have the same properties?
    Piezoelectric materials with significantly different Curie temperatures have different other characteristics.

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