A method for manufacturing a bonded substrate, the method includes: bonding a first mother substrate including a first substrate and a second mother substrate including a second substrate to form a bonded mother substrate; cutting off a part of the first mother substrate along a dividing line of the bonded mother substrate to form a cutoff portion; dividing the bonded mother substrate along the dividing line; separating a bonded substrate from the bonded mother substrate, the bonded substrate including the first substrate and the second substrate bonded to the first substrate; forming a contact terminal on an end portion of the first mother substrate, the contact terminal contactable with an external terminal; forming a communication path between the first mother substrate and the second mother substrate along the dividing line.

A piezoelectric film includes a plurality of laminated main baking unit PZT layers. A first seed layer is present at a lower surface side of a lowermost main baking unit PZT layer. A second seed layer is interposed between two adjacent main baking unit PZT layers at an intermediate position between the lowermost main baking unit PZT layer and an uppermost main baking unit PZT layer.

According to one embodiment, a method of manufacturing a piezoelectric element, includes forming lower electrodes on an insulating substrate, applying a precursor solution on the insulating substrate and the lower electrodes, drying the precursor solution by firing, thus forming a first precursor layer, patterning the first precursor layer into a shape of a plurality of islands located on the lower electrodes, respectively and crystallizing the island-shaped first precursor layer by firing, thus forming first piezoelectric layers.

According to one embodiment, a method of manufacturing a piezoelectric element, includes forming lower electrodes on an insulating substrate, applying a precursor solution on the insulating substrate and the lower electrodes, drying the precursor solution by firing, thus forming a first precursor layer, patterning the first precursor layer into a shape of a plurality of islands located on the lower electrodes, respectively and crystallizing the island-shaped first precursor layer by firing, thus forming first piezoelectric layers.

An electric current based on electric charge produced on the piezoelectric body changes by going through a first path, a second path, a third path, and a fourth path in this order. On the first path, the electric current becomes larger as the voltage becomes higher. On the second path, the electric current becomes smaller as the voltage becomes higher. On the third path, the electric current becomes larger as the voltage becomes higher. On the fourth path, the electric current becomes smaller as the voltage becomes higher.

A piezoelectric element including a piezoelectric layer having a perovskite structure including lead, zirconium, and titanium, and an electrode provided on the piezoelectric layer is provided. In the piezoelectric layer, in a range of 50 nm or smaller from an interface between the piezoelectric layer and the electrode in a thickness direction, a ratio c/a of a lattice spacing a in a direction perpendicular to the thickness direction and a lattice spacing c in the thickness direction satisfies 0.986≤c/a≤1.014.

A film structure body has: a substrate that is a silicon substrate including an upper surface composed of a (100) plane; an orientation film including a zirconium oxide film that is cubic crystal (100)-oriented on the upper surface; and a conductive film including a platinum film that is cubic crystal (100)-oriented on the orientation film.

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 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 ultrasonic sensor includes a vibration plate that includes a vibration portion and is formed of a resin; a wall portion that is provided on the vibration plate, surrounds the vibration portion and is formed of a resin; and a piezoelectric element that is provided in the vibration portion of the vibration plate. Accordingly, the wall portion surrounding the vibration portion can suppress a frequency variation of an ultrasonic wave output from the ultrasonic sensor and can deform the ultrasonic sensor into a shape corresponding to a surface of an object having various shapes.