The first conclusive experimental demonstration of the piezoelectric effect was published in 1880 by Pierre and Jacues Curie. Their experiment consisted of a conclusive measurement of charge showing in some prepared crystals (tourmaline, quartz, topaz, cane sugar...). They did not predict that the effect would show a reverse process until it was mathematically found from fundamental thermodynamic principles by Lippmann in 1881.
Piezoelectricity was first largly used during the World War I period and again in During World War II. To see someof these uses during at those times, look under aplications.