Provided are a piezoelectric element having high stability, which operates with high efficiency, and a method for manufacturing the piezoelectric element. The piezoelectric element (10) has a laminate structure in which a first electrode (14), a first piezoelectric film (16), a second electrode (18), an adhesion layer (20), an interlayer (22), a third electrode (24), a second piezoelectric film (26), and a fourth electrode (28) are laminated in this order on a silicon substrate (12). The interlayer (22) is formed of a material different from that of the second electrode (18) and has a thickness of 0.4 μm to 10 μm. A device having a diaphragm structure or a cantilever structure is formed by removing a part of the silicon substrate (12). The respective layers (14 to 28) laminated on the silicon substrate (12) can be formed using a thin film formation method represented by a vapor phase epitaxial method.

In an embodiment, a multilayer piezoelectric element includes a multilayer piezoelectric body and multiple internal electrodes. The multilayer piezoelectric body has a pair of principal faces in a first-axis direction, a pair of end faces in a second-axis direction crossing at right angles with the first-axis direction and defining the longitudinal direction, and a pair of side faces in a third-axis direction crossing at right angles with the first-axis direction and second-axis direction. The multiple internal electrodes are placed inside the multilayer piezoelectric body and stacked in the first-axis direction. Among the multiple internal electrodes, a center internal electrode placed at the center part of the multilayer piezoelectric body is such that its first cross-sectional shape, as viewed from the third-axis direction, has undulations greater than the undulations of the second cross-sectional shape of the center internal electrode as viewed from the second-axis direction.

A magnetic tunnel junction (MTJ) device includes two magnetic tunnel junction elements and a metal interconnection. The two magnetic tunnel junction elements are arranged side by side at a first direction. The metal interconnection is disposed between the magnetic tunnel junction elements, wherein the metal interconnection includes a contact plug part having a long shape at a top view, and the long shape has a length at a second direction larger than a width at the first direction, wherein the second direction is orthogonal to the first direction.

The invention provides a planarization method, which can make the local flatness of the product to be processed more uniform. The product has a cavity filled with oxide and includes a first electrode layer, a piezoelectric layer and a second electrode layer superposed on the cavity. The first electrode layer covers the cavity and includes a first inclined face around the first electrode layer, and the piezoelectric layer covers the first electrode layer and is arranged on the first electrode layer. The planarization method includes: depositing a passivation layer on the second electrode layer and etching the passivation layer completely until the thickness of the passivation layer is reduced to the required thickness.

A multi-layer piezoelectric microactuator assembly has at least one poled and active piezoelectric layer and one poled but inactive piezoelectric layer. The poled but inactive layer acts as a constraining layer in resisting expansion or contract of the first piezoelectric layer thereby reducing or eliminating bending of the assembly as installed in an environment, thereby increasing the effective stroke length of the assembly. Poling only a single layer would induce stresses into the device; hence, polling both piezoelectric layers even though only one layer will be active in use reduces stresses in the device and therefore increases reliability.

The present disclosure provides an ultrasonic transducer and a method for manufacturing an ultrasonic transducer, a display substrate and a method for manufacturing a display substrate. The method for manufacturing the ultrasonic transducer includes: forming a via hole in a substrate; forming a structural layer on a side of the substrate, the structural layer cover the via hole; and etching the structural layer from a side of the substrate away from the structural layer by using the substrate formed with the via hole as a blocking layer, to form a cavity at a position of the structural layer corresponding to that of the via hole.

A piezoelectric element includes a piezoelectric material layer and an electrode layer, wherein the piezoelectric material layer and the electrode layer are stacked on top of each other, the piezoelectric material layer includes a barium titanate-based material, and two coercive fields Ec1 and Ec2 of the piezoelectric element have the same sign and satisfy (|Ec2|−|Ec1|)≥8 kV/cm.

A micro-vibration sensor and preparation method thereof. The method includes a metal sheet is coated with first curing material, and first curing material is cured into first cured layer; piezoelectric thin film element is attached to edge of first cured layer; one side, attached with piezoelectric thin film element, of first cured layer is vertically placed into second curing material, and second curing material is cured into second cured layer; and metal sheet is removed to obtain micro-vibration sensor. Due to fact that piezoelectric thin film element is arranged at a crack tip, during micro-vibration, stress in stress field of crack tip is rapidly increased due to crack stress deformation, and stress signal is efficiently converted into electric signal; and micro-vibration sensor has characteristics of being low in detection limit and high in accuracy.

A piezoelectric element including a first electrode provided above a base body, a first piezoelectric layer provided so as to be in contact with the base body and cover the first electrode, a second piezoelectric layer provided above the first piezoelectric layer, and a second electrode provided above the second piezoelectric layer, wherein the first piezoelectric layer includes a composite oxide that contains potassium and niobium and that has a perovskite-type structure containing potassium as a main component at an A-site, the second piezoelectric layer includes a composite oxide that contains potassium, sodium, and niobium and that has a perovskite-type structure, and the first piezoelectric layer has a higher potassium atomic concentration (atm %) than the second piezoelectric layer.

A piezoelectric composition according to the present invention comprising: a carbon, and a main component composed of an alkali metal niobate based compound. The amount of carbon contained is 350 to 700 ppm by weight.