How to make a piezo ceramic
Manufacturing piezo ceramics is most similar to baking cookies!
Just follow the pictures below, they are almost self explanatory.
© image with the kind permission of Meggitt Denmark
To fabricate PZT we need some granular lead-oxide, titanium-dioxide, zirconia and maybe some dopants. The raw materials are milled to the right grain size and mixed in the right proportion. The mixture is then calcined, this means heating in air to about 900°C and after that milled again to accelerate the reaction of the components. By adding a binder the powder granulates and is now a paste ready to be pressed into the desired shape. Now the so called green ceramic is heated to some 600 or 700°C to burn out the binder. The temperature is then risen to about 1200 to 1300°C. This is called sintering whereby the grains are baked together to form the final hard ceramic. Now the parts can be ground, polished or lapped to obtain the desired precision and surface quality. At the end electrodes are applied by either screen printing of a conductive paste or by sputtering. The last step is the poling. This is done in hot oil by applying an electrical field of several kV/mm.