In a MEMS device in which a first electrode layer, a piezoelectric layer, and a second electrode layer are stacked in this order from a first surface side of a substrate, a first wiring layer is stacked on a second surface on a side opposite to a first surface of the substrate and the first electrode layer and the first wiring layer are connected to each other via a through wiring passing through the substrate.

A piezoelectric element includes, on a base, an underlying layer for controlling crystallinity of a piezoelectric layer, and the piezoelectric layer. The piezoelectric layer includes a crystal with an ABO.sub.3-type structure having at least Pb at A sites. In the underlying layer, an interface-with-the-base side is configured including at least Pb and another substance with a different composition rate from that of the piezoelectric layer at the A sites, and a substance with a different composition ratio from that of the piezoelectric layer at B sites. In a layer above the interface-with-the-base side in the underlying layer, the composition rate of the other substance included at the A sites of the underlying layer progressively changes and also the composition ratio of the substance included at the B sites progressively changes, from the interface-with-the-base side toward the interface-with-the-piezoelectric-layer side to approach the composition of the piezoelectric layer.

A functional ink that includes a precursor sol-gel solution and a solvent is provided. The precursor sol-gel solution is used for forming an oxide dielectric film having a perovskite structure represented by a general formula ABO.sub.3, and has been subjected to a partial hydrolysis process in which a viscosity change resulting from the partial hydrolysis process is controlled to be less than or equal to 50%, and water contained in the precursor sol-gel solution is controlled to be greater than or equal to 0.50 times and less than or equal to 10 times by molar ratio with respect to a B site atom contained in the precursor sol-gel solution. The functional ink has a metal oxide concentration and a viscosity that renders the functional ink suitable for being discharged from a nozzle of a liquid droplet discharge apparatus included in a thin film fabrication apparatus.

A piezoelectric element includes a laminate including first and second piezoelectric layers with respective polarization directions in a thickness direction and an elastic layer provided between the first piezoelectric layer and the second piezoelectric layer, first and second terminal electrodes that are provided on an external surface of the laminate, a first detection electrode provided on a positive polar surface of the first piezoelectric layer, a second detection electrode provided on a negative polar surface of the first piezoelectric layer, a third detection electrode provided on a positive polar surface of the second piezoelectric layer, and a fourth detection electrode provided on a negative polar surface of the second piezoelectric layer. The first detection electrode and the fourth detection electrode are connected to the first terminal electrode. The second detection electrode and the third detection electrode are connected to the second terminal electrode.

Multifunctional Boron Nitride nanotube-Boron Nitride (BN—BN) nanocomposites for energy transducers, thermal conductors, anti-penetrator/wear resistance coatings, and radiation hardened materials for harsh environments. An all boron-nitride structured BN—BN composite is synthesized. A boron nitride containing precursor is synthesized, then mixed with boron nitride nanotubes (BNNTs) to produce a composite solution which is used to make green bodies of different forms including, for example, fibers, mats, films, and plates. The green bodies are pyrolized to facilitate transformation into BN—BN composite ceramics. The pyrolysis temperature, pressure, atmosphere and time are controlled to produce a desired BN crystalline structure. The wholly BN structured materials exhibit excellent thermal stability, high thermal conductivity, piezoelectricity as well as enhanced toughness, hardness, and radiation shielding properties. By substituting with other elements into the original structure of the nanotubes and/or matrix, new nanocomposites (i.e., BCN, BCSiN ceramics) which possess excellent hardness, tailored photonic bandgap and photoluminescence, result.

Disclosed is a (K,Na)NbO.sub.3 (abbreviated by “KNN”)-based single crystal ceramic. The KNN-based single crystal ceramic according to the present disclosure is formulated by (K.sub.0.5−x/2Na.sub.0.5−x/2−y□.sub.y/2M.sub.x+y/2)Nb.sub.1−x/3+yO.sub.3, wherein M indicates a metal having a different valence from Na, and □ indicates a metal vacancy. The above formulated KNN-based single crystal ceramic allows compensating for the volatilization of Na in a growing grain due to the addition of M.sup.2+ ions, and substituting M.sup.2+ ions for Na.sup.+ ions to form metal vacancies, thereby making possible the single crystal growth.

A piezoelectric device includes a body provided with a first region and a second region lined along a first direction. The first region deformably extends/contracts along the first direction. The second region deformably curves in such a manner that one or the other side in a second direction intersecting the first direction curves outward.

Provided are a barium titanate-based piezoelectric ceramics having satisfactory piezoelectric performance and a satisfactory mechanical quality factor (Q.sub.m), and a piezoelectric element using the same. Specifically provided are a piezoelectric ceramics, including: crystal particles; and a grain boundary between the crystal particles, in which the crystal particles each include barium titanate having a perovskite-type structure and manganese at 0.04% by mass or more and 0.20% by mass or less in terms of a metal with respect to the barium titanate, and the grain boundary includes at least one compound selected from the group consisting of Ba.sub.4Ti.sub.12O.sub.27 and Ba.sub.6Ti.sub.17O.sub.40, and a piezoelectric element using the same.

Disclosed is a piezoelectric element wherein a lower electrode made of Pt, a buffer layer made of PLT, and a piezoelectric thin film to be a perovskite ferroelectric thin film are formed in this order on a substrate. The average crystal grain size of Pt forming the lower electrode is not smaller than 50 nm and not larger than 150 nm.

An acoustic wave device includes: a support substrate; a first piezoelectric substrate bonded to a first principal surface of the support substrate, the first piezoelectric substrate being a single crystal substrate, a first acoustic wave resonator located on an opposite surface of the first piezoelectric substrate from a surface to which the support substrate is bonded, the first acoustic wave resonator including an IDT; a second piezoelectric substrate bonded to a second principal surface of the support substrate opposite from the first principal surface, the second piezoelectric substrate being a single crystal substrate; and a second acoustic wave resonator located on an opposite surface of the second piezoelectric substrate from a surface to which the support substrate is bonded, the second acoustic wave resonator including an IDT.