A piezoelectric film includes a substrate having flexibility, and at least two piezoelectric elements provided to the substrate so as to be arranged at intervals of a first dimension along a first direction, the piezoelectric elements are each configured by stacking a first electrode film, a piezoelectric film made of an inorganic material, and a second electrode film along a thickness direction of the substrate, and an area between the piezoelectric elements adjacent to each other along the first direction forms a vibrational region which can be displaced in the thickness direction.

A piezoelectric thin film 3 contains a metal oxide, the metal oxide contains bismuth, potassium, titanium, iron and element M, the element M is at least one of magnesium and nickel, at least a part of the metal oxide is a crystal having a perovskite structure, and a (001) plane, a (110) plane or a (111) plane of the crystal is oriented in a normal direction dn of the surface of the piezoelectric thin film 3.

A piezoelectric element includes: a first electrode and a second electrode; and a piezoelectric layer provided between the first electrode and the second electrode and having a perovskite structure, in which 0<P1/P2≤0.5 and 0<P1 where, when a positive predetermined voltage is applied to the piezoelectric layer, then a voltage applied to the piezoelectric layer is set to 0 V for 0.1 seconds, and then a triangular wave voltage waveform having a maximum voltage of the predetermined voltage is applied to the piezoelectric layer to obtain a hysteresis curve drawn counterclockwise, P1 is a residual polarization amount at a start point of the hysteresis curve and P2 is a residual polarization amount at an end point of the hysteresis curve.

An ultrasonic fingerprint recognition sensor and a manufacturing method thereof, and a display device are disclosed. The ultrasonic fingerprint recognition sensor includes a resonant cavity, a receiver electrode, a drive electrode, and a piezoelectric thin film layer between the receiver electrode and the drive electrode, the resonant cavity is on a side, closer to the piezoelectric thin film layer, of the receiver electrode, and is configured to increase vibration amplitude of the piezoelectric thin film layer.

An electronic device includes a substrate layer having a front surface and a back surface opposite the front surface, a plurality of ultrasonic transducers formed on the front surface of the substrate layer, wherein the plurality of ultrasonic transducers generate backward waves during operation, the backward waves propagating through the substrate layer, and a plurality of substrate structures formed within the back surface of the substrate layer, the plurality of substrate structures configured to modify the backward waves during the operation.

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.

In a piezoelectric device, when viewed in a direction perpendicular to one main surface, an outer shape of a recess is a polygonal shape or a circular shape. When n represents a number of sides of the polygonal shape, r represents a radius of a circumscribed circle of an imaginary regular polygon including n sides with a length identical to a length of a shortest of the sides, and d represents a maximum thickness of a membrane portion, which is located above the recess, of a multilayer portion, r≤197.7dn.sup.−0.6698 when 3≤n≤7, and r≤52.69d when 8≤n or when the outer shape of the recess is a circular shape.

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.