Provided is a piezoelectric film formed by a vapor phase growth method, the piezoelectric film containing: a perovskite oxide in which a perovskite oxide represented by the following formula P is doped with Si in an amount of from 0.2 mol % to less than 0.5 mol %, wherein a ratio of a peak intensity of a pyrochlore phase to a sum of peak intensities in respective plane orientations of (100), (001), (110), (101) and (111) of a perovskite phase measured by an X-ray diffraction method is 0.25 or less:
A.sub.1+?[(Zr.sub.xTi.sub.1?x).sub.1?aNb.sub.a]O.sub.yFormula P wherein, in formula P, A is an A-site element primarily containing Pb; Zr, Ti, and Nb are B-site elements; x is more than 0 but less than 1; a is 0.1 or more but less than 0.3.

An elastic wave device includes elastic wave elements, each including a piezoelectric layer directly or indirectly supported by a supporting substrate and an electrode disposed in contact with the piezoelectric layer, and a highly heat-conductive member stacked on a surface of the supporting substrate, opposite to the surface supporting the piezoelectric layer, in which the thermal conductivity of the supporting substrate is higher than the thermal conductivity of the piezoelectric layer, the coefficient of linear expansion of the supporting substrate is lower than the coefficient of linear expansion of the piezoelectric layer, the highly heat-conductive member has a larger area than the surface of the supporting substrate supporting the piezoelectric layer, and the thermal conductivity of the highly heat-conductive member is higher than that of the piezoelectric layer.

A piezoelectric element includes a substrate, a first electrode formed on the substrate, a piezoelectric layer, which is a layered structure of a plurality of piezoelectric films each containing potassium, sodium, and niobium, formed on the first electrode, and a second electrode formed on the piezoelectric layer. A sodium concentration in the piezoelectric layer has a Na local maximum value, which is a local maximum value of the sodium concentration, in a first piezoelectric film, which is among the plurality of piezoelectric films, in the vicinity of the first electrode, a sodium concentration gradient decreasing from the Na local maximum value toward the second electrode, and a Na local minimum value, which is a local minimum value of the sodium concentration, near a boundary between the first piezoelectric film and a second piezoelectric film formed immediately above the first piezoelectric film.

A piezoelectric element has a diaphragm, a first electrode on the diaphragm, a piezoelectric layer on the first electrode, and a second electrode on the piezoelectric layer. The piezoelectric layer is a stack of multiple piezoelectric films and is made of a perovskite composite oxide containing lead, zirconium, and titanium and represented by the general formula ABO.sub.3, with the molar ratio of the A-site to the B-site (A/B) in the perovskite composite oxide being 1.14 or more and 1.22 or less. In current-time curve measurement, the activation energy calculated from relaxation current using an Arrhenius plot is 0.6 [eV] or less. The relaxation current is the amount of current at the time at which a downward trend in current turns upward.

A piezoelectric element includes a first electrode, a second electrode, and a piezoelectric layer. The piezoelectric layer is provided between the first electrode and the second electrode, and is formed of a perovskite type oxide which contains potassium, sodium, niobium, and manganese. In the piezoelectric layer, a proportion of an A-site constituent element of the perovskite type oxide is smaller than a proportion of a B-site constituent element thereof. In XRD measurement of the piezoelectric layer, two or more peaks derived from the perovskite type oxide are provided in a range of 44?<2?<48?, and an intensity ratio (X/Y) between a peak X having the highest intensity among the peaks, and a peak Y having the lowest intensity satisfies the following expression.

2.0<(X/Y)

A supporting film is provided on an opening and a wall of a substrate. A piezoelectric film is provided on a first region of the supporting film corresponding to the opening and a second region of the supporting film corresponding to the wall. The thickness of the piezoelectric film at the second region is smaller than that of the piezoelectric film provided at the first region. Therefore, vibration of the piezoelectric film in the first region is large, and vibration of the piezoelectric film in the second region is small. This alleviates disadvantages such as a loss of the vibration characteristics of a piezoelectric element.

An optical reflective device includes: a movable part configured to be rotated about a rotation axis; a reflection surface located on the movable part; a frame part connected to the movable part at two positions symmetrical about the rotation axis; torsion part extending along the rotation axis; a connection part connecting one end of the torsion part to the frame part; a drive part connected to another end of the torsion part and configured to rotate the torsion part about the rotation axis; and a fixation part supporting the drive part, the connection part has higher rigidity than the torsion part, at least one pair of joint surfaces are formed at a boundary between the torsion part and the connection part, and the one pair of joint surfaces are symmetrical about the rotation axis and each have an acute angle on the torsion part side with the rotation axis.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

An imaging system includes: a transceiver cell for generating a pressure wave and converting an external pressure wave into an electrical signal; and a control unit for controlling an operation of the transceiver cell. The transceiver cell includes: a substrate; at least one membrane suspending from the substrate; and a plurality of transducer elements mounted on the at least one membrane. Each of the plurality of transducer elements has a bottom electrode, a piezoelectric layer on bottom electrode, and at least one top electrode on the piezoelectric layer. Each of the plurality of transducer element generates a bending moment in response to applying an electrical potential across the bottom electrode and the at least one top electrode and develops an electrical charge in response to a bending moment due to the external pressure wave.

A piezoelectric element has a first piezoelectric layer, a second piezoelectric layer on the first piezoelectric layer, and an electrode layer on the second piezoelectric layer, in which the first piezoelectric layer and the second piezoelectric layer have pores, and the porosity of the second piezoelectric layer is lower than the porosity near the interface on the second piezoelectric layer side of the first piezoelectric layer.