High Performance Piezoceramic Materials

Piezoceramic devices are subjected to high loads yet expected to perform with strong reliability. CeramTec has addressed this need by developing a range of special high-performance materials suitable for piezoelectric engineering. With their diverse characteristics and application features, our SONOX® material range has earned an excellent reputation in the world of sensors, actuators, and transducers.

Material Categories

Piezoceramic materials are classified according to their chemical composition on the one hand and according to specific application conditions on the other. Selection criteria include typical performance parameters as well as specific material behavior under high electrical and mechanical loads.

A basic distinction is made between two material categories:

Group I: SONOX® P4, SONOX® P8

SONOX® P4 and SONOX® P8 materials are capable of handling high control voltages and high mechanical pressure loads. Main features include the following:

• low dielectric losses
• dielectric constants between 1000 and 1400
• high Q factor (between 500 and 2000)
• high Curie temperatures
• high coercive field strength

SONOX® P4 and SONOX® P8 materials are particularly suitable for high-power ultrasonic applications covering frequencies from 20 kHz to MHz-ranges.

Group II: SONOX® P5, SONOX® P51, SONOX® P502, SONOX® P53

SONOX® P5, SONOX® P51, SONOX® P502 and SONOX® P53 materials are characterized by

• dielectric constants between 1000 and 4000
• high piezoelectric activity (d33 > 400x10^-12 C/N)
• low Q factors (100)

Table 1. Group II materials are used in a wide range of sensors and actuators.

High Performance Ceramics for Engineered Products

Basic Oscillation Modes of Piezoelectric Resonators

The piezoelectric material specifications depicted in the following data tables are expressed in terms of specific parameters. The values of these parameters are determined under small-signal conditions using standard test specimens, and are subject to variation with time and temperature. Measurements are therefore commonly conducted between 20° C and 25° C at 24 hours after polarization. To facilitate the interpretation of the data, the illustration on the right offers an overview of the geometrical boundary conditions used in testing for the various oscillation modes.

Figure 1. Basic oscillation modes of piezoelectric resonators

Curie Temperature

Temperature at which the permittivity of ferroelectric ceramics reaches its peak. Above this temperature the ceramic material will not exhibit piezoelectric properties.

Dielectric Constant

Ratio of the permittivity of the material to the permittivity of free space ()

=8.85x10^-12 F/m

Dielectric Dissipation Factor

Dielectric dissipation factor (tan ) is the ratio between power loss and reactive power in a specimen subjected to a sine-wave input at a frequency far below its first self-resonant frequency (usually measured at 1 kHz).

Free Capacitance

Capacitance of a piezoelectric resonator is measured at a level far below its lowest self-resonant frequency (usually 1 kHz).

Electromechanical Coupling Coefficient

Factor representing the ratio between the energy converted and stored and the energy absorbed by a piezoceramic part. Depending on the boundary conditions, there are five different coupling factors reflecting the component's shape factor and oscillation mode.

Piezoelectric Charge Coefficient

Ratio of the electrical charge generated per unit area to an applied force; expressed in Coulomb/Newton.

Piezoelectric Voltage Coefficient

Ratio of electric field produced to the mechanical stress applied; expressed as Voltmeter/Newton.

Mechanical Quality Factor (Q_m)

Amplitude magnification of oscillating piezoelectric parts in a resonant state. This is a non-dimensional factor indicating the mechanical loss of the component under dynamic operating conditions.

This information has been sourced, reviewed and adapted from materials provided by CeramTec.

For more information on this source, please visit CeramTec.