A piezoelectric ceramic, which does not contain lead as a constituent element, is characterized in that: its primary component is a perovskite compound expressed by the composition formula (Bi.sub.0.5−x/2Na.sub.0.5−x/2Ba.sub.x)(Ti.sub.1−yMn.sub.y)O.sub.3 (where 0.01≤x≤0.25, 0.001≤y≤0.020); and the coefficient of variation (CV) in grain size among the grains contained therein is 35 percent or lower. The piezoelectric ceramic presents an improved dielectric loss tangent tan δ.

An electronic device may include a first electrode, a first magnetostrictive layer coupled to the first electrode, a plurality of alternating ferromagnetic and insulating layers stacked above the first magnetostrictive layer, a second electrode electrically coupled to an intermediate ferromagnetic layer in the stack of ferromagnetic and insulating layers, a second magnetostrictive layer above the stack of ferromagnetic and insulating layers, and a third electrode electrically coupled to the second magnetostrictive layer. At least one ferromagnetic layer below the intermediate ferromagnetic layer may be switchable between different polarization states responsive to a first voltage applied across the first and second electrodes, and at least one ferromagnetic layer above the intermediate ferromagnetic layer may be switchable between different polarization states responsive to a second voltage applied across the second and third electrodes.

An apparatus includes a vibration member and a first cover disposed at a rear surface of the vibration member. The apparatus also includes a first vibration apparatus disposed at a rear surface of the first cover and configured to vibrate the vibration member. The apparatus includes a first enclosure member disposed at the rear surface of the first cover and at the rear surface of the vibration member. The apparatus also includes a first rear vibration member disposed at the first enclosure member.

A semiconductor substrate with oxide single crystal heterostructures, to which a sacrificial layer, an epitaxy functional oxide thin film having a perovskite structure and a metal layer are grown on an oxide single crystal substrate, prepared another metal layer on a semiconductor substrate, and bonded the metal layer of the oxide single crystal substrate to the metal layer of the semiconductor substrate to be face each other, and separated the oxide single crystal substrate by selectively etching and removing only the sacrificial layer after the bonding.

A piezoelectric composition comprises an oxide having a perovskite structure, wherein the oxide contains bismuth, barium, iron and titanium; the X-ray diffraction pattern of the piezoelectric composition after a polarization treatment has a first peak and a second peak in the range of the diffraction angle 2θ of 38.6° or more and 39.6° or less; the diffraction angle 2θ of the first peak is smaller than the diffraction angle 2θ of the second peak; an intensity of the first peak is represented as I.sub.L; an intensity of the second peak is represented as I.sub.H; and I.sub.H/I.sub.L is 0.00 or more and 2.00 or less.

A barium titanate fiber is useful as a filler for a polymer composite piezoelectric body, a polymer composite piezoelectric body has high piezoelectric properties, and a piezoelectric element utilizes the polymer composite piezoelectric body. In the barium titanate fiber, the molar ratio of barium atoms to titanium atoms (Ba/Ti ratio) falls within the range of 1.01 to 1.04. The polymer composite piezoelectric body includes a resin composition containing the barium titanate fiber and a polymer. The piezoelectric element including an electrically conductive layer on one surface or both surfaces of the polymer composite piezoelectric body.

A vibration wave motor includes an element configured to be displaced by application of voltage, and an annular elastic body having a bottom surface coming into contact with the element and a drive surface having a groove, configured to drive a moving element by a vibration wave produced on the drive surface by displacement of the element. The element has a density of 4.2 to 6.0×10.sup.3 kg/m.sup.3. A value of [(T/B)÷W] is in a range of 0.84 to 1.94, where T represents a depth of the groove, B represents a distance from a bottom part of the groove to the bottom surface, and W represents a radial width of the elastic body.

Provided is a piezoelectric ceramics having a gradual change in piezoelectric constant depending on an ambient temperature. Specifically, provided is a single-piece piezoelectric ceramics including as a main component a perovskite-type metal oxide represented by a compositional formula of ABO.sub.3, wherein an A site element in the compositional formula contains Ba and M.sub.1, the M.sub.1 being formed of at least one kind selected from the group consisting of Ca and Bi, wherein a B site element in the compositional formula contains T1 and M.sub.2, the M.sub.2 being formed of at least one kind selected from the group consisting of Zr, Sn, and Hf, wherein concentrations of the M.sub.1 and the M.sub.2 change in at least one direction of the piezoelectric ceramics, and wherein increase and decrease directions of concentration changes of the M.sub.1 and the M.sub.2 are directions opposite to each other.

An optical element includes a primary electrode, a secondary electrode overlapping at least a portion of the primary electrode, and an electrostrictive ceramic layer disposed between and abutting the primary electrode and the secondary electrode, where the electrostrictive ceramic may be characterized by a relative density of at least approximately 99%, an average grain size of at least approximately 300 nm, a transmissivity within the visible spectrum of at least approximately 70%, and bulk haze of less than approximately 10%. Optical properties of the electrostrictive ceramic may be substantially unchanged during the application of a voltage to the electrostrictive ceramic layer and the attendant actuation of the optical element.

A lead-free piezoelectric material includes perovskite-type metal oxide containing Na, Nb, Ba, Ti, and Mg and indicates excellent piezoelectric properties. The piezoelectric material satisfies the following relational expression (1): 0.430≤a≤0.460, 0.433≤b≤0.479, 0.040≤c≤0.070, 0.0125≤d≤0.0650, 0.0015≤e≤0.0092, 0.9×3e≤c−d≤1.1×3e, a+b+c+d+e=1, where a, b, c, d, and e denote the relative numbers of Na, Nb, Ba, Ti, and Mg atoms, respectively.