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.

Described herein is a method of bonding a piezoelectric substrate to a support substrate to form a composite substrate. The piezoelectric substrate has one surface which is positively polarized, and a second surface which is negatively polarized. The method described herein includes the steps of bonding the positively polarized surface of the piezoelectric substrate to one surface of the support substrate by a direct bonding method.

A piezoelectric monocrystalline substrate is composed of a material represented by LiAO.sub.3 (A represents at least one element selected from the group consisting of niobium and tantalum), a bonding layer is compose of a material of an oxide of at least one element selected from the group consisting of niobium and tantalum, and an interface layer is provided along an interface between the piezoelectric monocrystalline substrate 6 and bonding layer, and the interface layer has a composition of E.sub.xO.sub.(1-x) (E represents at least one element selected from the group consisting of niobium and tantalum and 0.29≤x≤0.89).

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.

An elastic wave device includes a supporting substrate, an acoustic multilayer film on the supporting substrate, a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate. The acoustic multilayer film includes at least four acoustic impedance layers. The at least four acoustic impedance layers include at least one low acoustic impedance layer and at least one high acoustic impedance layer having an acoustic impedance higher than the low acoustic impedance layer. The elastic wave device further includes a bonding layer provided at any position in a range of from inside the acoustic impedance layer, which is the fourth acoustic impedance layer from the piezoelectric substrate side towards the supporting substrate side, to an interface between the acoustic multilayer film and the supporting substrate.

A SAW device includes a SAW element, a conductor connected to the SAW element, an LT substrate including the SAW element, and a case for housing the LT substrate including the SAW element. The case includes a cover part, a lateral part, and a bottom part. The bottom part is including a sapphire substrate, the LT substrate is positioned on a first surface of the sapphire substrate, the first surface serving as an inner surface of the case, and a second surface opposite to the first surface serves as an outer surface of the case. The conductor includes a via conductor provided in a through-hole continuously penetrating through the sapphire substrate and the LT substrate.

A composite substrate 10 includes a semiconductor substrate 12 and an insulating support substrate 14 that are laminated together. The support substrate 14 includes first and second substrates 14a and 14b made of the same material and bonded together with a strength that allows the first and second substrates 14a and 14b to be separated from each other with a blade. The semiconductor substrate 12 is laminated on a surface of the first substrate 14a opposite a surface thereof bonded to the second substrate 14b.

A method for treating a layer of composition ABO.sub.3, wherein A is a first material composition consisting of at least one element selected from the group consisting of: Li, Na, K, H, Ca, Mg, Ba, Sr, Pb, La, Bi, Y, Dy, Gd, Tb, Ce, Pr, Nd, Sm, Eu, Ho, Zr, Sc, Ag, and Tl, and wherein B is a second material composition consisting of at least one element selected from the group consisting of: Nb, Ta, Sb, Ti, Zr, Sn, Ru, Fe, V, Sc, C, Ga, Al, Si, Mn, Zr, and Tl, is described. The method includes implanting an ionic species into a donor substrate of the composition ABO.sub.3, thereby forming a weakened zone delineating the layer, detaching the layer from the donor substrate along the weakened zone, and exposing the detached layer to a medium containing ions of a constituent element A, such that the ions penetrate into the layer.

A vibrator includes: a base portion; a vibrating arm including an arm portion which extends from the base portion, and a weight portion which is located on a tip end side of the arm portion and which has a first main surface and a second main surface that are in a front-back relationship; and a weight film disposed at the first main surface of the weight portion. The first main surface includes a planar surface and an inclined surface inclined with respect to the planar surface. A method for manufacturing a vibrator includes: a preparation step of preparing the above-described vibrator; and a removing step of removing a part of the weight film by emitting an energy ray to the weight film. In the removing step, the weight film disposed at the planar surface is removed and the weight film disposed at the inclined surface is not removed by emitting the energy ray to the weight film from a normal direction of the planar surface.

A liquid discharge head includes a nozzle to discharge a liquid, an individual chamber communicating with the nozzle, a supply channel communicating with the individual chamber to supply the liquid to the individual chamber, and a discharge channel communicating with the individual chamber to discharge the liquid in the individual chamber. A fluid resistance of the supply channel is greater than a fluid resistance of the discharge channel.