Piezoelectric substrate, piezoelectric element, liquid discharge head and liquid discharge apparatus

A method for manufacturing a piezoelectric substrate, the piezoelectric substrate of a perovskite-type oxide expressed by a general formula of ABO3 having a single crystal structure or a uniaxial crystal structure expressed by (Pb1-xMx)xm(ZryTi1-y)O3, where M represents an element selected from La, Ca, Ba, Sr, Bi, Sb and W, the piezoelectric substrate having a structure layered above a substrate, the layered structure having a first crystal phase layer provided at a side nearest to the substrate and having a tetragonal crystal structure, a second crystal phase layer having a crystal structure selected from a rhombohedral structure, a pseudocubic structure and a monoclinic structure, and a boundary layer arranged between said the first crystal phase layer and the second crystal phase layer, a crystal structure of the boundary layer gradually changing in a thickness direction of the boundary layer, the method performing in the following order:

• a forming step of the first crystal phase layer by performing sputtering using a material of the first crystal phase layer as a target, an amount of Ti contained in the material of the first crystal phase layer being more than that contained in a material of the second crystal phase layer and that contained in a material of the boundary layer;
• a forming step of the boundary layer by performing sputtering while gradually changing a material of the target from the material of the first crystal phase layer to that of the second crystal phase layer;
• and
• a forming step of the second crystal phase layer by performing sputtering using the material of the second crystal layer as the target.