There is provided an MEMS device in which a first substrate provided with a driving element and a second substrate protecting the driving element are bonded to each other with an adhesive, in which the driving element is formed inside the space surrounded by the adhesive between the first substrate and the second substrate, an open hole which communicates with the space and the outside of the adhesive is formed on the adhesive, and an end of the outside of the open hole is provided to be with an end of the first substrate and an end of the second substrate.

A piezoelectric element includes: a first electrode; an oxide layer formed on the first electrode; a piezoelectric layer formed on the oxide layer and containing potassium, sodium, and niobium; and a second electrode formed on the piezoelectric layer. When a potential difference of 10 V is applied between the first electrode and the second electrode, a current density of a leak current differs by 10,000 times or more between a case in which the first electrode is set at a high potential and a case in which the second electrode is set at a high potential.

A piezoelectric substrate includes: a substrate; a first electrode formed on the substrate; and a piezoelectric layer formed on the first electrode and containing potassium, sodium, and niobium. A full width at half maximum of an X-ray intensity peak on a plane (100) of the piezoelectric layer in a Psi axis-direction scan result of an X-ray diffraction measurement in which a surface of the piezoelectric layer is irradiated with X-rays at an angle of 54.74° from a direction perpendicular to the surface is more than 0° and 1.2° or less.

A piezoelectric body contains potassium, sodium, and niobium, and has a perovskite structure. A Raman shift of peaks assigned to A.sub.1g obtained by performing Raman spectroscopic analysis on a plurality of measurement regions is 400 cm.sup.−1 or more and 700 cm.sup.−1 or less. A difference between a maximum value and a minimum value of the Raman shift among the peaks in the plurality of measurement regions is 11.0 cm.sup.−1 or less.

A flow passage forming member includes flow passage forming member main bodies 140 and 146 that are formed of a resin material and define at least a part of a flow passage, a metal protective film 200 that is provided on a surface of the flow passage forming member main body 140 and a surface of the flow passage forming member main body 146 defining at least the flow passage and is formed of a metal material, and a protective film 210 that is laminated on the metal protective film 200 and contains an oxide or a nitride of at least on element selected from the group consisting of tantalum (Ta), titanium (Ti), zirconium (Zr), niobium (bib), vanadium (V), hafnium (Hf), silicon (Si), aluminum (Al), tungsten (W), and yttrium (Y).

There is provided a piezoelectric element which includes a first electrode which is formed on a substrate, a piezoelectric layer which is formed on the first electrode, and is formed from a compound oxide having an ABO.sub.3 type perovskite structure in which potassium (K), sodium (Na), niobium (Nb), and manganese (Mn) are provided, and a second electrode which is formed on the piezoelectric layer. The manganese includes bivalent manganese (Mn.sup.2+), trivalent manganese (Mn.sup.3+), and tetravalent manganese (Mn.sup.4+). A molar ratio (Mn.sup.2+/Mn.sup.3++Mn.sup.4+) of the bivalent manganese to a sum of the trivalent manganese and the tetravalent manganese is equal to or greater than 0.31.

There is provided a liquid ejecting head which is long in a first direction and short in a second direction, including: a first introduction section; a second introduction section; a first filter chamber group having a first filter chamber and a second filter chamber; a second filter chamber group having a third filter chamber and a fourth filter chamber; a first supply flow path for supplying the liquid from the first introduction section to the first filter chamber group; and a second supply flow path for supplying the liquid from the second introduction section to the second filter chamber group, in which the first introduction section, the second introduction section, the first filter chamber group, and the second filter chamber group are arranged side by side in this order in the first direction.

A liquid ejecting head includes a pressure chamber substrate in which a pressure chamber space is formed, a flow path substrate having a first surface on which the pressure chamber substrate is installed and a second surface that is on the opposite side to the first surface, and in which a first space, a supply hole that enables communication between the first space and the pressure chamber space, and a communication hole that communicates with the pressure chamber space are formed, a nozzle plate that is installed on the second surface and in which a nozzle that communicates with the communication hole is formed, a second space that is installed on the first surface and that communicates with the first space of the flow path substrate, a housing unit in which an opening portion that communicates with the second space is formed, a compliance unit that is flexible and installed on the second surface and that seals the communication hole and the first space, and a beam-like portion that extends between inner wall surfaces of the second space in the housing unit.

A liquid ejecting head includes: a sealing substrate provided in such a way as to cover the first piezoelectric element and the second piezoelectric element; a wiring board configured to apply a voltage to a common electrode, a first individual electrode, and a second individual electrode; a first wiring portion provided above the pressure chamber substrate and configured to electrically couple the common electrode to the wiring board; a second wiring portion provided at a lower surface of the sealing substrate and configured to electrically couple the common electrode to the wiring board; and a third wiring portion provided between the first piezoelectric element and the second piezoelectric element and configured to electrically couple the first wiring portion to the second wiring portion.

A liquid ejecting apparatus includes: a liquid ejecting head including an ejecting surface configured to eject a liquid; a tank that reserves the liquid to be supplied to the liquid ejecting head; a circulating mechanism that executes a circulating operation to circulate the liquid between the liquid ejecting head and the tank; and a control unit that controls the circulating mechanism. The control unit executes a recording operation by the liquid ejecting head in a first posture in which the ejecting surface crosses a horizontal plane and executes the circulating operation in a second posture in which an angle made by the ejecting surface and the horizontal plane is smaller than the angle in the first posture.