Definition
A crystalline material, such as quartz or certain ceramics, that produces a small electrical voltage when mechanically squeezed, struck, or otherwise stressed, and conversely changes shape when a voltage is applied across it.
Plain English
A special crystal that creates a tiny burst of electricity when you press or hit it, and that flexes slightly when electricity is run through it.
Context Anchor
Seen in powerplant discussions of ignition components and engine pressure or vibration sensing devices.
Derivation
From the Greek piezein, meaning 'to press or squeeze,' combined with 'electric.' The name literally describes the effect: pressure produces electricity.
Why Pilots Care
Many sensors a maintenance technician handles -- detonation sensors, vibration pickups, and some pressure probes -- rely on this effect. Understanding it helps explain why these sensors are wired carefully, handled gently, and tested with the right equipment.
Analogy
A common everyday example is the click button on some grill lighters. Pressing the button squeezes a piezoelectric material and creates a small electrical output.
Grounding Statement
Pressing the crystal makes electricity; sending electricity into the crystal makes it move.
Intuition Check
Do not think of “crystal” here as a decorative gem. In this context, it means a solid material with a structure that can create an electrical signal when pressure or vibration acts on it.
Example Sentence 1
The engine's detonation sensor uses a piezoelectric crystal to convert combustion vibrations into a small electrical signal sent to the engine control unit.
Example Sentence 2
During overhaul, the team verified that the piezoelectric crystal in the pressure transducer responded correctly to applied force.