An acoustic wave device has a substrate, an optional functional layer disposed over at least a portion of the substrate, a piezoelectric layer disposed over at least a portion of the functional layer and/or substrate, and an interdigital transducer electrode disposed on the piezoelectric layer. The piezoelectric layer has an outer edge spaced inward of an outer edge of the substrate, the outer edge of the piezoelectric layer being tapered at an angle relative to a surface of the substrate to thereby reduce an acoustic reflection magnitude at said outer edge of the piezoelectric layer.

A piezoelectric actuator 10 includes: a piezoelectric element 11; an external electrode 12 covering partially a first surface 11a of the piezoelectric element 11 in a first direction; a wiring member 14; and a conductive joining member 20 joining the wiring member 14 to the external electrode 12, wherein the conductive joining member 20 has an air gap 70 formed between the external electrode 12 and the wiring member 14 in a region overlapping with the wiring member 14 as viewed in the first direction, and wherein the conductive joining member 20 extends to an edge 21 of the external electrode 12 or extends to the first surface 11a of the piezoelectric element 11 beyond the edge 21 of the external electrode 12.

In a piezoelectric device, electrode layers are spaced apart from each other in the direction of the normal thereto. A first piezoelectric layer is interposed between two electrode layers of electrode layers in the direction of the normal. A second piezoelectric layer is provided on an opposite side of the first piezoelectric layer from a base portion. The second piezoelectric layer is interposed between two electrode layers of the electrode layers in the direction of the normal. The half-width of a rocking curve measured by X-ray diffraction for a lattice plane of the first piezoelectric layer substantially parallel to a first main surface is smaller than a half-width for the second piezoelectric layer. The piezoelectric constant of a material defining the first piezoelectric layer is smaller than the piezoelectric constant of a material defining the second piezoelectric layer.

In a piezoelectric device, electrode layers are spaced apart from each other in the direction of the normal thereto. A first piezoelectric layer is interposed between two electrode layers of electrode layers in the direction of the normal. A second piezoelectric layer is provided on an opposite side of the first piezoelectric layer from a base portion. The second piezoelectric layer is interposed between two electrode layers of the electrode layers in the direction of the normal. The half-width of a rocking curve measured by X-ray diffraction for a lattice plane of the first piezoelectric layer substantially parallel to a first main surface is smaller than a half-width for the second piezoelectric layer. The piezoelectric constant of a material defining the first piezoelectric layer is smaller than the piezoelectric constant of a material defining the second piezoelectric layer.

A piezoelectric transducer device includes a support, a piezoelectric element, a first connecting element and a second electrical connecting element, the piezoelectric element being carried by the support and each of the first and second electrical connecting elements being electrically connected, respectively, to a first area and a second area, distinct from the first area, of the piezoelectric element, the piezoelectric element including a lower face opposite the support and an upper face, opposite to the lower face, wherein the upper face is integrally exposed or is covered, partially or not, only with the second electrical connecting element.

The present invention relates to a cantilever for a piezoelectric energy harvesting system, wherein the cantilever (2,20,30) comprises two layers (21,22,31,32) formed of polyvinylidene fluoride, and wherein a core layer (23,33) formed of a shim material is sandwiched between the two layers (21,22,31,32) formed of polyvinylidene fluoride

A vortex-induced vibration wind energy harvesting device, including an array consisting of a plurality of oscillators and a plurality of piezoelectric microelectromechanical systems (MEMSs), is provided. An oscillator is mounted on each of the piezoelectric MEMSs. When any one of the oscillators is oscillated by and resonant with vortex shedding due to an incoming airflow, its vortices in the wake will enhance the oscillation of the downstream oscillators, so that overall oscillation of the oscillators in the array is strengthened. The piezoelectric MEMSs are deformed by the vibration of these oscillators to generate voltage and current to output. In the present invention, the oscillators are arranged closely. When the airflow passes the array, even weak airflow can generate periodic force and cause significant oscillation due to resonance. The MEMS can convert mechanical energy into electrical energy and output it in order to achieve the purpose of wind energy harvesting.

A multilayer structure and a piezoelectric device using the same, which have satisfactory crystal orientation even in the submicron region of the thickness of a piezoelectric layer, are provided. The multilayer structure includes a first wurtzite thin film, a first hexagonal metal layer, a first electrode layer, a second hexagonal metal layer, and a second wurtzite thin film stacked in this order. The first electrode layer is formed of a metallic material having an acoustic impedance higher than that of the second wurtzite thin film.

A multilayer structure and a piezoelectric device using the same, which have satisfactory crystal orientation even in the submicron region of the thickness of a piezoelectric layer, are provided. The multilayer structure includes a first wurtzite thin film, a first hexagonal metal layer, a first electrode layer, a second hexagonal metal layer, and a second wurtzite thin film stacked in this order. The first electrode layer is formed of a metallic material having an acoustic impedance higher than that of the second wurtzite thin film.

A piezoelectric composition including manganese and a complex oxide having a perovskite structure represented by a general formula ABO.sub.3, wherein an A site element in the ABO.sub.3 is potassium or potassium and sodium, a B site element in the ABO.sub.3 is niobium, a concentration distribution of the manganese has a variation, and the variation shows a CV value of 35% or more and 440% or less.