An active portion of a piezoelectric actuator includes a first region provided in a region opposed to a recess and extending in a first direction, and a second region provided in a region corresponding to a central part in the first direction of the recess, and being configured such that a laminated body including the active portion and a vibration plate has a thickness larger than a thickness of a portion corresponding to the first region and that deformation of the second region is suppressed as compared to deformation of the first region when a voltage is applied between a first electrode and a second electrode.

A liquid ejecting head includes: an actuator including a piezoelectric element and a vibrating plate; and a pressure chamber substrate including a pressure chamber whose volume changes when the vibrating plate deforms, in which 0.35×FR1≤FR2<1.00×FR1, where one position in a longitudinal direction of the pressure chamber is a first position, another position closer than the first position to an end of the pressure chamber in the longitudinal direction of the pressure chamber is a second position, bending rigidity of the actuator in the thickness direction at the first position is FR1, and bending rigidity of the actuator in the thickness direction at the second position is FR2.

An electromechanical transducer includes an electromechanical transducer film of laminated layers including a perovskite-type complex oxide represented by a general formula of ABO.sub.3; and a pair of electrodes opposed to each other with the electromechanical transducer film interposed between the pair of electrodes. In the general formula of ABO.sub.3, A includes Pb and B includes Zr and Ti. A variable ratio ΔPb of Pb, determined by Pb(max)−Pb(min), is 6% or less and a variable ratio ΔZr of Zr, determined by Zr(max)−Zr(min), is 9% or less, where an atomic weight ratio of Pb in the electromechanical transducer film is denoted by Pb/B, an atomic weight ratio of Zr in the electromechanical transducer film is denoted by Zr/B, a maximum value and a minimum value of the atomic weight ratio of Pb in a film thickness direction of the electromechanical transducer film are denoted by Pb(max) and Pb(min), respectively, and a maximum value and a minimum value of the atomic weight ratio of Zr in the film thickness direction of the electromechanical transducer film are denoted by Zr(max) and Zr(min), respectively.

A piezoelectric element 10 includes a lower electrode, constituted of a Pt/Ti laminated film, a PLT seed layer, formed on the lower electrode, a PZT piezoelectric film, formed on the PLT seed layer, and an upper electrode, formed on the PZT piezoelectric film. A curve Q1 is a curve drawn such as to pass through a plurality of plotted points, each expressing a PLT (100) peak intensity with respect to a Pt (111) peak intensity according to a substrate setting temperature during forming of the Pt/Ti laminated film. A relationship of the PLT (100) peak intensity with respect to the Pt (111) peak intensity is within a range in the curve Q1 until the PLT (100) peak intensity decreases by 5% from a peak point P, at which the PLT (100) peak intensity is the maximum, and a (100) orientation rate of PLT constituting the seed layer is not less than 85%.

A method of and system for adhesive bonding. The method and system a) treat a surface of an element to be bonded to provide an adherent structure including one or more rubber compounds on the surface; b) place a polymerizable adhesive composition, including at least one photoinitiator and at least one energy converting material, in contact with the adherent structure and two or more components to be bonded to form an assembly, c) irradiated the assembly with radiation at a first wavelength, capable of conversion by the at least one energy converting material, to a second wavelength capable of activating the at least one photoinitiator to produce from the polymerizable adhesive composition a cured adhesive composition; and d) adhesively join the two or more components by way of the adherent structure and the cured adhesive composition.

A thin-film piezoelectric material elements are arranged on a thin-film piezoelectric material substrate. The thin-film piezoelectric material substrate includes an insulator on Si substrate including a substrate including silicon and an insulating layer on a surface of the substrate. The thin-film piezoelectric material element includes a thin-film laminated part on a top surface of the insulating layer. The thin-film laminated part includes a YZ seed layer including yttrium and zirconium, and formed on the top surface; a lower electrode film laminated on the YZ seed layer; a piezoelectric material film including lead zirconate titanate, shown by a formula Pb (Zr.sub.xTi.sub.(1-x)) O.sub.3(0≤×≤1), and an upper electrode film laminated on the piezoelectric material film. The thin-film laminated part further includes an upper piezoelectric-material protective-film, laminated on the upper side of the upper electrode film.

A piezoelectric element 10 includes a lower electrode, constituted of a Pt/Ti laminated film, a PLT seed layer, formed on the lower electrode, a PZT piezoelectric film, formed on the PLT seed layer, and an upper electrode, formed on the PZT piezoelectric film. A curve Q1 is a curve drawn such as to pass through a plurality of plotted points, each expressing a PLT (100) peak intensity with respect to a Pt (111) peak intensity according to a substrate setting temperature during forming of the Pt/Ti laminated film. A relationship of the PLT (100) peak intensity with respect to the Pt (111) peak intensity is within a range in the curve Q1 until the PLT (100) peak intensity decreases by 5% from a peak point P, at which the PLT (100) peak intensity is the maximum, and a (100) orientation rate of PLT constituting the seed layer is not less than 85%.

A piezoelectric ceramic composition is represented by a composition formula A.sub.xBO.sub.3 and includes potassium sodium niobate containing K and Na that account for 80% or more of an amount of A-site elements and containing Nb that accounts for 70% or more of an amount of B-site elements. The piezoelectric ceramic composition contains Ta and Fe at a B-site.

A substrate for liquid ejection head comprising, a base material, a heating element including a heating resistor layer for generating thermal energy for discharging a liquid, a wiring layer for supplying electric power to the heating element, and an interlayer insulating film for insulating the heating resistor layer and the wiring layer. A part of a first interlayer insulating film for insulating the heating resistor layer and a first wiring layer adjacent to the heating resistor layer, and a second interlayer insulating film for insulating the first wiring layer and a second wiring layer adjacent to the second interlayer insulating film, includes a material layer represented by Si.sub.wO.sub.xC.sub.yN.sub.z (w+x+y+z=100 (at. %), 37≤w≤60 (at. %), 30≤x≤53 (at. %), 6≤y≤−29 (at. %), 4≤z≤9 (at. %)).

Long-term reliability of a liquid ejection head substrate and a liquid ejection head is improved by suppressing dissolution of an intermediate layer due to anodization. A liquid ejection head substrate including: a flow passage forming member having an ejection orifice and a flow passage; a heating resistance element for ejecting a liquid; an insulating layer covering the heating resistance element; a protecting layer whose surface is exposed to the flow passage; and an intermediate layer provided between the flow passage forming member and the protecting layer, in which the intermediate layer contains a material represented by a following composition formula (I): Si.sub.w1O.sub.x1C.sub.y1 (I), 39≤w1≤62 (at. %), 32≤x1≤55 (at. %), and 6≤y1≤29 (at. %), and w1+x1+y1=100 (at %).