Piezoelectric element, liquid ejection head, and liquid ejection apparatus

Abstract

A piezoelectric element includes a substrate, a first electrode disposed on the substrate, a piezoelectric layer disposed on the first electrode and containing potassium, sodium, and niobium, and a second electrode disposed on the piezoelectric layer, wherein the piezoelectric layer includes a first layer disposed on the first electrode, and a second layer disposed on the first layer, the piezoelectric layer includes a first region including a first interface between the first layer and the second layer, and a second region located inside the first layer without including the first interface, and a molar ratio of potassium to sodium in the first region is higher than the molar ratio in the second region.

Dependencies are inferred from the claim text.