Advanced Piezo Materials, for Standard and OEM Components and Assemblies

PI Ceramic provides a wide selection of advanced piezoelectric ceramic materials based on modified Lead Zirconate Titanate (PZT) and Barium Titanate. The material properties are classified according to the EN 50324 European Standard. In addition to the standard types described here in detail, a large number of modifications are available which have been adapted to a variety of applications. Internationally, the convention is to divide piezo ceramics into two groups. The terms "soft" and "hard" PZT ceramics refer to the mobility of the dipoles or domains and hence also to the polarization and depolarization behavior.

"Soft" Piezo Ceramic Materials

Characteristic features are a comparably high domain mobility and resulting "soft ferroelectric" behavior, i.e. it is relatively easy to polarize. The advantages of the "soft" PZT materials are their large piezo- electric charge coefficient, moderate permittivities and high coupling factors.
Important fields of application for "soft" piezo ceramics are actuators for micropositioning and nanopositioning, sensors such as conventional vibration pickups, ultrasonic transmitters and receivers for flow or level measurement, for example, object identification or monitoring as well as electro-acoustic applications as sound transducers and microphones, through to their use as sound pickups on musical instruments.

"Hard" Piezo Ceramic Materials

"Hard" PZT materials can be subjected to high electrical and mechanical stresses. Their properties change only little under these conditions and this makes them particularly ideal for high-power applications. The advantages of these PZT materials are the moderate permittivity, large piezoelectric coupling factors, high qualities and very good stability under high mechanical loads and operating fields. Low dielectric losses facilitate their continuous use in resonance mode with only low intrinsic warming of the component. These piezo elements are used in ultrasonic cleaning (typically kHz frequency range), for example, the machining of materials (ultrasonic welding, bonding, drilling, etc.), for ultrasonic processors (e.g. to disperse liquid media), in the medical field (ultrasonic tartar removal, surgical instruments etc.) and also in sonar technology.

Lead-Free Piezo Materials

Piezoelectric ceramics, which nowadays are based mainly on Lead Zirconate-Lead Titanate compounds, are subject to an exemption from the EU directive to reduce hazardous substances (RoHS) and can therefore be used without hesitation. PI Ceramic is nevertheless aiming to provide high-performance lead-free piezoceramic materials and thus provide materials with a guaranteed future. PI Ceramic is currently investigating technologies to reliably manufacture lead-free ceramic components in series production.

First Steps Towards Industrial Use with PIC 700

The PIC 700 material, which is currently in laboratory production, is the first lead-free piezo ceramic material being offered on the market by PI Ceramic. PIC 700 is based on Bismuth Sodium Titanate (BNT) and has very similar characteristics to Barium Titanate materials. PIC 700 is suitable for ultrasonic transducers in the MHz range as well as sonar and hydrophone applications.

Characteristics of the Lead-Free Piezo Ceramic Material

The maximum operating temperature of the BNT-based ceramic is around 200 °C. The permittivity and piezoelectric coupling factors of BNT components are lower than those of conventional, PZT materials. Even though PIC 700 is suitable for a number of applications, an across-the-board replacement for PZT piezoelectric elements in technical applications is not in sight at the moment.

Crystalline Piezo Material for Actuators

Lead-Free and with High Linearity

Piezoceramic actuators exhibit nonlinear displacement behavior: The voltage applied is thus not a repeatable measure for the position reached. Sensors must therefore be used in applications where the position is relevant. The crystalline PIC 050 material, in contrast, has a linearity which is significantly improved by a factor of 10 so that a position sensor is not necessary.
PIC 050 is used for actuators and nanopositioning systems with the tradename Picoactuator®. They have the high stiffness and dynamics of actuators made of PZT material but their displacement is limited: Travel of up to +/-3 µm results with a maximum profile of 20 mm.

Picoactuator® in Nanopositioning

In precision positioning technology, Physik Instrumente (PI) uses these actuators precisely where this small displacement with high dynamics and accuracy is required. The high linearity means that they can operate without position control which otherwise sets an upper limit for the dynamics of the system as a result of the limited control bandwidth.
Since it is used in positioning systems the PIC 050 material is only supplied as a translational or shear actuator in predefined shapes. The standard dimensions are similar to those of the PICA shear actuators.

"Soft" PZT

Material designation	General description of the material properties	Classification in accordance with EN 50324-1	as an alternative to DOD-STD-1376A
PIC 151	PIC 151 is a modified lead zirconate - lead titanate piezoelectric ceramics material with high permittivity, high coupling factor and high piezoelectric charge constant. This material is the standard material for actuators (PICA^TM Series) and suitable for low-power ultrasonic transducers and low-frequency sound transducers.	600	II
PIC 255	PIC 255 is a modified piezoelectric ceramics material with extremely high Curie temperature, high permittivity, high coupling factor and high charge constant. The material has been optimized for actuator applications under dynamic conditions and high ambient temperatures. The high coupling factor, low mechanical quality factor and low temperature coefficient make this material particularly suitable for low-power ultrasonic transducers, nonresonant broadband systems, and for force and acoustic pickups.	200	II
PIC 155	PIC 155 is a modification of the PIC 255 piezoelectric ceramics material distinguished by high piezoelectric stress coefficients and lower frequency constants. It is used in applications where a high g-constant is required, such as in microphones and vibration pickups with preamplifier.	200	II
PIC 153	PIC 153 is a modified lead zirconate - lead titanate piezoelectric ceramics material with extremely high permittivity and coupling factors, a high charge constant, and a Curie temperature of around 185 °C. This material is suitable for hydrophones, transducers in medical diagnostics and PZT translators.	600	VI
PIC 152	PIC 152 is a PZT material whose permittivity has an especially low temperature coefficient.	200	II

"Hard" PZT

Material designation	General description of the material properties	Classification in accordance with EN 50324-1	as an alternative to DOD-STD-1376A
PIC 181	PIC 181 is a modified lead zirconate lead titanate material with an extremely high mechanical quality factor and a high Curie temperature. This material is destined for the use in high-power acoustic applications. Furthermore, the good temperature and time stability of its dielectric and elasticity constants makes it suitable for resonance-mode ultrasonic applications and it has proved to be particularly successful in piezomotor drives.	100	I
PIC 141	PIC 141 is a modified piezoelectric ceramics material with high a mechanical quality factor and a comparatively moderate permittivity. This material is designed for use in high-power acoustic applications and is also used for pharmaceutical atomizers.	100	I
PIC 241	PIC 241 PZT ceramic is distinguished by its high mechanical quality factor and comparatively high permittivity. Its fields of application lie in high-power ultrasonic devices and it is used for piezomotor drives.	100	I
PIC 300	PIC 300 is a modified lead zirconate - lead titanate material with a very high Curie temperature. It is suitable for applications at temperatures up to 250°C (300°C for short durations).	100	I

Barium lead titanate piezo materials

Material designation	General description of the material properties	Classification in accordance with EN 50324-1	as an alternative to DOD-STD-1376A
PIC 110	PIC 110 is a modified barium titanate piezoelectric ceramics material with a Curie temperature of 150°C. Its low acoustic impedance makes this material especially suitable for sonar and hydrophonic applications.	400	IV