Piezoelectric PZT Cell: encased in acrylic is a cylinder of ceramic PZT material which when suddenly compressed generates more than 30kV allowing a spark to jump across a 1cm gap. This vintage 1970s demonstration (still available) uses a lever and cam mechanism to compress the piezo ceramic which is connected via conductors to the spark gap. The piezoelectric effect is the ability of certain materials to generate electric charge when deformed under mechanical stress. Lead (Pb) Zirconate Titanate