Piezoelectric laminate, surface acoustic wave device, thin-film piezoelectric resonator, and piezoelectric actuator

A piezoelectric device comprising:

• a lower electrode;
• a piezoelectric layer formed above the lower electrode and having a compositional formula (KaNa1-a)xNbO3;
• and
• an upper electrode formed above the piezoelectric layer,
• wherein “a” is 0.1<a<1 and “x” is 1≦x≦1.2, and
• the piezoelectric layer changes from an orthorhombic crystal to a rhombohedral crystal or to a monoclinic crystal at −40° C. or less, and
• the piezoelectric layer includes a first piezoelectric layer and a second piezoelectric layer formed between the lower electrode and the first piezoelectric layer, the first piezoelectric layer and the second piezoelectric layer include potassium sodium niobate, and the second piezoelectric layer includes potassium and sodium which are A-site elements in excess in comparison with those in the first piezoelectric layer.