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.
Medical diagnostics and treatment
Ultrasonic welding and drilling
Special material types
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
Temperature at which the permittivity of ferroelectric ceramics reaches its peak. Above this temperature the ceramic material will not exhibit piezoelectric properties.
Ratio of the permittivity of the material to the permittivity of free space ()
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).
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 (Qm)
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.