QUESTION:

What is the thermal expansion coefficient for Ferroperm PZT?

ANSWER:

• Apart from being material-dependent, the data for this parameter are unfortunately separated into several different categories. Values for Ferroperm's two standard PZT materials, Pz26 and Pz27 will be given here.
• For an unpoled sample it is relatively simple, since there is no anisotropy in the material yet. You should be able to use the following general values:
  
  

  T interval	TEC(Pz26) (10-6 K-1)	T interval	TEC(Pz27) (10-6 K-1)
  0 - 100°C	+1.75	0 - 150°C	+2.0
  100 - 200°C	+1.0	150 - 250°C	+1.5
  200 - 250°C	+0.5

For the poled material, the situation is much more complicated.
Firstly, there is apparently a big difference between the first heating and subsequent heatings. If this is a critical point for your process, we would therefore recommend to heat-treat the material (for example 0.5 - 1h at 220ºC) before assembly. If possible, this should be done in stress-free and short-circuit conditions.
Secondly, the material is now anisotropic, and you therefore have to differentiate between the 1 and 3 directions. The general values for subsequent heatings are

- in the 3-direction:


T interval	TEC(Pz26) (10-6 K-1)	TEC(Pz27) (10-6 K-1)
0 - 50°C	+1.5	+4.0
50 - 100°C	0.0	+4.0
100 - 150°C	-1.0	+2.0
150 - 200°C	-1.5	0.0
200 - 250°C	-2.5	-2.0

- in the 1-direction:

T interval	TEC(Pz26) (10-6 K-1)	TEC(Pz27) (10-6 K-1)
0 - 100°C	+4.0	+1.5
100 - 150°C	+4.0	+2.0
150 - 200°C	+4.0	+3.0
200 - 250°C	+3.5	+4.0