A piezoelectric actuator includes a first electrode, a first piezoelectric body disposed at one side of the first electrode in a thickness direction of the first electrode, an individual electrode disposed at one side of the first piezoelectric body in the thickness direction, a second piezoelectric body disposed at one side of the individual electrode in the thickness direction, a second electrode disposed at one side of the second piezoelectric body in the thickness direction, a wiring that electrically connects to the individual electrode, a first contact, and a second contact. At the first and the second contacts, the first electrode and the second electrode electrically connect to each other. The first contact is disposed at one side of the individual electrode in a perpendicular direction perpendicular to the thickness direction. The second contact is disposed at the other side of the individual electrode in the perpendicular direction.

An actuator includes a substrate, a diaphragm on the substrate, a lower electrode on the diaphragm, a piezoelectric body on the lower electrode, and an upper electrode on the piezoelectric body. A ratio of lead (Pb) and zirconium (Zr) in atomic percent (atm %) present at a grain boundary in the piezoelectric body satisfies a relation of Pb/Zr>1.7.

An optical assembly of a projection exposure apparatus for semiconductor lithography comprises an optical element and an actuator for deforming the optical element. The actuator is subjected to a bias voltage by a controller that is present. A projection exposure apparatus for semiconductor lithography comprises an optical assembly. A method for operating an actuator for deforming an optical element for semiconductor lithography comprises subjecting the actuator to a bias voltage by a controller.

A sound producing package structure includes a first sub-package structure and a second sub-package structure. The first sub-package structure includes a first substrate having a first opening and a first chip including a first membrane, wherein a first cavity is formed between the first membrane and the first substrate. The first sub-package structure and the second sub-package structure are stacked, and the second sub-package structure includes a second substrate and a second chip. The second substrate is connected to the first substrate and has a second opening. The second chip includes a second membrane, wherein a second cavity is formed between the second membrane and the second substrate. A gap, connected to the first opening and the second opening, is formed between the first substrate and the second substrate, such that an ambient of the sound producing package structure, the first cavity and the second cavity are connected.

A liquid discharge head includes a flow passage member, a sealing member, and an actuator member. The flow passage member is formed with individual flow passages each including a nozzle and a pressure chamber and the flow passage member has a surface on which the pressure chamber is open. The sealing member is arranged on the surface and seals the pressure chamber. The actuator member has a piezoelectric layer, a driving electrode, and a high electric potential portion. The piezoelectric layer is adhered to a first surface of the sealing member on a side opposite to the flow passage member, via a first adhesive having an insulating property. The driving electrode is arranged on a side opposite to the sealing member with respect to the piezoelectric layer at a position overlapped with the pressure chamber in a first direction orthogonal to the surface.

Provided is a piezoelectric ceramics having a gradual change in piezoelectric constant depending on an ambient temperature. Specifically, provided is a single-piece piezoelectric ceramics including as a main component a perovskite-type metal oxide represented by a compositional formula of ABO.sub.3, wherein an A site element in the compositional formula contains Ba and M.sub.1, the M.sub.1 being formed of at least one kind selected from the group consisting of Ca and Bi, wherein a B site element in the compositional formula contains T1 and M.sub.2, the M.sub.2 being formed of at least one kind selected from the group consisting of Zr, Sn, and Hf, wherein concentrations of the M.sub.1 and the M.sub.2 change in at least one direction of the piezoelectric ceramics, and wherein increase and decrease directions of concentration changes of the M.sub.1 and the M.sub.2 are directions opposite to each other.

A piezoelectric micromachined ultrasound transducer (PMUT) array may comprise PMUT devices with respective piezoelectric layers and electrode layers. Parasitic capacitance can be reduced when an electrode layer is not shared across PMUT devices but may expose the devices to electromagnetic interference (EMI). A conductive layer located within the structural layer or on a shared plane with the electrode layers may reduce EMI affecting the PMUT array operation.

There is provided a piezoelectric actuator, including: a vibration plate; a first piezoelectric body; a second piezoelectric body; a first electrode disposed on a first surface of the first piezoelectric body; a second electrode disposed on a second surface of the second piezoelectric body; an intermediate electrode disposed on an intermediate surface of the first piezoelectric body and overlapping with the first and second electrodes; an intermediate trace connected to the intermediate electrode on the intermediate surface and drawn out to one side in a first direction beyond the first piezoelectric body and the second piezoelectric body; a first trace overlapping with the intermediate trace in the thickness direction and being conducted with the intermediate trace; and a second trace overlapping with the intermediate trace in the thickness direction and being conducted with the intermediate trace.

A lead-free piezoelectric material includes perovskite-type metal oxide containing Na, Nb, Ba, Ti, and Mg and indicates excellent piezoelectric properties. The piezoelectric material satisfies the following relational expression (1): 0.430≤a≤0.460, 0.433≤b≤0.479, 0.040≤c≤0.070, 0.0125≤d≤0.0650, 0.0015≤e≤0.0092, 0.9×3e≤c−d≤1.1×3e, a+b+c+d+e=1, where a, b, c, d, and e denote the relative numbers of Na, Nb, Ba, Ti, and Mg atoms, respectively.

A foil transducer for a valve, including at least one firmly arranged holding part, at least one displaceable force transmission part, an electroactive foil composite structure and at least two electrodes. The electroactive foil composite structure has an actuating direction in which the electroactive foil composite structure is extended on actuation. The actuating direction lies in a plane spanned by the electroactive foil composite structure.