A micro-electrical-mechanical system (MEMS) guided wave device includes a single crystal piezoelectric layer and at least one guided wave confinement structure configured to confine a laterally excited wave in the single crystal piezoelectric layer. A bonded interface is provided between the single crystal piezoelectric layer and at least one underlying layer. A multi-frequency device includes first and second groups of electrodes arranged on or in different thickness regions of a single crystal piezoelectric layer, with at least one guided wave confinement structure. Segments of a segmented piezoelectric layer and a segmented layer of electrodes are substantially registered in a device including at least one guided wave confinement structure.

Piezoelectric transducers are provided. The piezoelectric transducer includes a first piezoelectric layer, a second piezoelectric layer disposed on at least a portion of the first piezoelectric layer, and a middle electrode layer disposed between the first and second piezoelectric layers, where the middle electrode layer includes an inner region and an outer region spaced apart from the inner region. Methods of making the piezoelectric transducers are also provided. The piezoelectric transducers and methods find use in a variety of applications, including devices, such as electronics devices having one or more (e.g., an array) of the piezoelectric transducers.

Provided are a polymer composite piezoelectric body in which the conversion efficiency between electricity and sound is increased and thus the sound pressure level is improved, an electroacoustic transduction film, and an electroacoustic transducer. The polymer composite piezoelectric body includes a viscoelastic matrix formed of a polymer material having a cyanoethyl group, piezoelectric body particles which are dispersed in the viscoelastic matrix and have an average particle diameter of more than or equal to 2.5 μm, and dielectric particles dispersed in the viscoelastic matrix, in which the dielectric particles are formed of a material different from that of the piezoelectric body particles and have an average particle diameter of less than or equal to 0.5 μm and a relative permittivity of more than or equal to 80.

An end-surface-reflection surface acoustic wave device, which reflects a surface acoustic wave between first and second end surfaces facing each other, includes a support substrate, an intermediate layer, a piezoelectric layer, and an IDT electrode. The first end surface is located at one end portion in a surface-acoustic-wave propagation direction and extends from a main surface of the piezoelectric layer to at least a portion of the intermediate layer. The second end surface is located at the other end portion in the surface-acoustic-wave propagation direction and extends from the main surface of the piezoelectric layer to at least a portion of the intermediate layer. The support substrate includes support substrate portions that are located outside the first and second end surfaces in the surface-acoustic-wave propagation direction.

A piezoelectric material including a perovskite-type metal oxide represented by the following general formula (1); Bi; and Mn, wherein the content of Bi is 0.1-0.5 mol % with respect to 1 mol of the metal oxide, the content of Mn is 0.3-1.5 mol % with respect to 1 mol of the metal oxide, and the piezoelectric material satisfies (L.sub.4−L.sub.5)/L.sub.5≧0.05 and (L.sub.8−L.sub.9)/L.sub.9≧0.05 when the lengths of twelve Bi—O bonds with Bi that is located at a 12-fold site with respect to O in a perovskite-type unit cell as a starting point are taken to be L.sub.1 to L.sub.12 in length order:

(Ba.sub.1-xM1.sub.x)(Ti.sub.1-yM2.sub.y)O.sub.3  (1)

wherein 0≦x≦0.2, 0≦y≦0.1, and M1 and M2 are mutually different metal elements which have a total valence of +6 and are selected from other elements than Ba, Ti, Bi and Mn.

In a surface acoustic wave filter, a parallel arm resonator includes an IDT electrode and reflectors. Comb-shaped electrodes of the IDT electrode each include a busbar electrode and electrode fingers connected thereto, and are arranged so that the electrode fingers of the respective comb-shaped electrodes are alternately located in a propagation direction of a surface acoustic wave. The reflectors are provided on both sides of the IDT electrode portion in the propagation direction of the surface acoustic wave so that reflector electrode fingers are parallel or substantially parallel to the electrode fingers. A distance between the electrode finger and the reflector electrode finger which are proximate to each other is about 10% or more and about 20% or less of a main pitch of the electrode fingers.

Aspects of this disclosure relate to a boundary acoustic wave device. The boundary acoustic wave device can include two low acoustic impedance layers, an interdigital transducer electrode, piezoelectric material positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers, and two high acoustic impedance substrates. The two low acoustic impedance layers can be positioned between the two high acoustic impedance substrates. Related acoustic wave filters, multiplexers, radio frequency modules, wireless communication devices, and methods are disclosed.

A piezoelectric device includes a support member, and a vibrating portion provided on a support surface of the support member. The vibrating portion includes, in addition to a first electrode, a piezoelectric film and a second electrode arranged in a stacking direction, an insulating film configured to increase an electric resistance value between the first and second electrodes. The first electrode is provided on the support surface of the support member, and includes an opening penetrating the first electrode in the stacking direction. The piezoelectric film is provided on the first electrode to extend across the opening. The second electrode is provided on the piezoelectric film. The insulating film is provided at a position between the first electrode and the second electrode, and at least a part of the insulating film overlaps with the opening in the stacking direction.

A piezoelectric device includes a support member, and a vibrating portion provided on a support surface of the support member. The vibrating portion includes, in addition to a first electrode, a piezoelectric film and a second electrode arranged in a stacking direction, an insulating film configured to increase an electric resistance value between the first and second electrodes. The first electrode is provided on the support surface of the support member, and includes an opening penetrating the first electrode in the stacking direction. The piezoelectric film is provided on the first electrode to extend across the opening. The second electrode is provided on the piezoelectric film. The insulating film is provided at a position between the first electrode and the second electrode, and at least a part of the insulating film overlaps with the opening in the stacking direction.

A piezoelectric device includes a base member, a first conductive film arranged above the base member in contact with an upper surface of the base member, a piezoelectric film arranged above the first conductive film in contact with an upper surface of the first conductive film, a second conductive film arranged on the piezoelectric film, and an insulating portion provided inside a trench penetrating through the piezoelectric film and the first conductive film. The insulating portion has a higher electrical resistivity than the piezoelectric film.