PI currently offers several types of long travel piezo linear motors and several types of short travel actuators such as flexure actuators, stack actuators, and bender actuators. The drive principle in piezo ceramic motors / actuators is intrinsically nonmagnetic and vacuum-compatible.
Piezo Motor Actuators
Stick-Slip Ratchet Type Piezo Motor Actuators (Screw Drives) are often used for set & forget type adjustments, replacing manual micrometers. They provide high resolution and holding forces, but low speed typically on the order of a few mm/minute.
Stick-Slip Direct-Drive Piezo Motor Actuators (Mini-Rod Drives) are compact ceramic linear motors with forces to 10N and speed to 10 mm/sec.
PiezoWalk® Linear Motors achieve holding forces to 800N and picometer range resolution; however they are more complex and typically used in high-end applications.
For more information on the differences between piezo motors and actuators and their applications, refer to the piezo motion tutorial.
Ultrasonic Piezo Motors are characterized by very high speed of 100's of mm/sec and a very compact design.
Information on vacuum compatible motorized actuators can be found here.