A piezoelectric member that achieves a high sound speed includes a silicon-containing substrate and a piezoelectric layer. The piezoelectric layer is disposed on the silicon-containing substrate. At least a surface layer of the piezoelectric layer on a side opposite to the silicon-containing substrate is made of B.sub.xAl.sub.1-xN (0<x≦0.2).

Provided is a dielectric thin film including a metal oxide. The metal oxide includes bismuth, sodium, barium, and titanium, at least a part of the metal oxide is a tetragonal crystal having a perovskite structure, and a (100) plane of at least a part of the tetragonal crystal is oriented in a normal direction do of a surface of the dielectric thin film 3.

A piezoelectric material contains a main component containing a perovskite-type metal oxide represented by general formula (1), a first sub-component containing Mn, and a second sub-component containing Bi or Bi and Li. A Mn content relative to 100 parts by weight of the metal oxide is 0.500 parts by weight or less (including 0 parts by weight) in terms of metal, a Bi content relative to 100 parts by weight of the metal oxide is 0.042 parts by weight or more and 0.850 parts by weight or less in terms of metal, and a Li content relative to 100 parts by weight of the metal oxide is 0.028 parts by weight or less (including 0 parts by weight) in terms of metal:
(Ba.sub.1−x−yCa.sub.xSn.sub.y).sub.α(Ti.sub.1−zZr.sub.z)O.sub.3 (where 0.020≦x≦0.200, 0.020≦y≦0.200, 0≦z≦0.085, 0.986≦α≦1.100)  General formula (1).

A piezoelectric material contains: a first component which is a rhombohedral crystal in a single composition, has a Curie temperature Tc1, and is a lead-free-system composite oxide having a perovskite-type structure; a second component which is a crystal other than a rhombohedral crystal in a single composition, has a Curie temperature Tc2 higher than Tc1, and is a lead-free-system composite oxide having a perovskite-type structure; and a third component which is a rhombohedral crystal in a single composition, has a Curie temperature Tc3 equal to or higher than Tc2, and is a lead-free-system composite oxide that has a perovskite-type structure and is different from the first component. When a molar ratio of the third component to the sum of the first component and the third component is α and α×Tc3+(1−α)×Tc1 is Tc4, |Tc4−Tc2| is 50° C. or lower.

A liquid-ejecting head includes a pressure-generating chamber communicating with a nozzle opening, and a piezoelectric element. The piezoelectric layer contains a perovskite complex oxide containing Bi, La, Fe, and Mn and is ferroelectric.

A residual stress in a PZT type ferroelectric film 12 formed on a substrate body 11 by a sol-gel process is −14 MPa to −31 MPa, and the ferroelectric film 12 is crystal oriented in a (100) plane.

Provided is a coating liquid for forming a piezoelectric thin film containing lead zirconate titanate, the coating liquid including a complex precursor containing at least three kinds of metal elements of Pb, Ti, and Zr, the coating liquid being free from an exothermic peak at a temperature of 450° C. or more, or having a heat generation amount at a temperature of from 400° C. to 450° C., which is larger than a heat generation amount at a temperature of from 450° C. to 500° C., in differential thermal analysis of the coating liquid.

There is provided a wafer processing method for dividing a wafer having a plurality of devices formed in regions partitioned by a plurality of crossing division lines on a front surface of a substrate having a birefringent crystal structure, into individual device chips. The wafer processing method includes a detection step of detecting the division line formed on the front surface of the wafer by an imaging unit from the back side of the wafer. In the detection step, a polarizer disposed on an optical axis connecting an imaging element and an image forming lens provided in the imaging unit intercepts extraordinary light appearing due to birefringence in the substrate and guides ordinary light to the imaging element.

A piezoelectric multilayer component having a stack of sintered piezoelectric layers and inner electrodes arranged between the piezoelectric layers. A region which has poling cracks is present on the surface of at least one electrode, and the poling cracks are separated from a surface of at least one of the inner electrodes by the region having the poling cracks.

A piezoelectric element having an improved piezoelectric constant is provided, and a liquid discharge head, an ultrasonic motor, and a dust removing device, each of which uses the above piezoelectric element, are also provided. A piezoelectric element at least includes a pair of electrodes and a piezoelectric material provided in contact with the pair of electrodes, the piezoelectric material is formed of an aggregate of crystal grains containing barium titanate as a primary component, and among the crystal grains of the aggregate, crystal grains at least in contact with the electrodes have dislocation layers in the grains. A liquid discharge head, an ultrasonic motor, and a dust removing device each use the above piezoelectric element.