The commonly used piezoelectric crystal is Rochelle Salt or potassium sodium tartrate.
We can make it our own.
1. Baking soda or Sodium bicarbonate- 500 g
2. Cream of tartar or Potassium bitartrate- 200 g
3. Distilled water- 250 mL
4. Filter paper
1. The baking soda is taken in baking pan and is spread evenly.
2. The baking pan in kept in the oven for 4 hours with 1st hour at 150K (65C), 2nd hour at 250K (120C), 3rd hour at 350K (175C) and 4th hour at 450K (230C).
3. Between these 4 hours we could do another part of the project.
4. 250 mL of distilled water is taken in a boiling cup.
5. The cream of tartar is put into the water and dissolved thoroughly.
6. Take a sauce pan containing some water. The boiling cup having cream of tartar solution is placed in it such that we can heat the mixture indirectly.
7. Now the sauce pan with boiling cup is put on the flame. After some time when the water in the pan starts to boil, add the heated baking soda little by little into the boiling cup until we get a get clear golden colour solution. It takes about 50 minutes.
8. Now the boiling cup is taken out and the solution is filtered using the filter paper.
9. This filtered solution is potassium sodium tartrate and it is allowed to cool and kept undisturbed for two weeks.
10. After two weeks we a crystalline structure and it is called piezoelectric crystal.