Abstract: Disclosed herein are piezoelectric ceramics composed of lead titanate zirconate, which is expressed in PbZr.sub.1-z Ti.sub.z O.sub.3, where z=0.45 to 0.54, with 0.1 to 8 mole percent of the Pb atoms being replaced with at least one element selected from a group of Ca, Sr and Ba, and containing Mn in a range of 0.005 to 0.9 percent by weight of the whole in terms of MnO.sub.2.

Abstract: A piezoelectric ceramic composition in which 0.1 to 8 mole % of a Pb atom in lead titanate zirconate is replaced with at least one of Ba, Sr and Ca, and which contains 0.5 to 1.9% by weight of at least one of Sb, Nb and Ta when respectively converted into Sb.sub.2 O.sub.3, Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5, contains 0.1 to 0.8% by weight of at least one of Cr, Fe and Mn when respectively converted into Cr.sub.2 O.sub.3, Fe.sub.2 O.sub.3 and MnO.sub.2, and contains 0.001 to 0.25% by weight of at least one of Si and Ge when respectively converted into SiO.sub.2 and GeO.sub.2.

Abstract: A method of driving a piezoelectric bimorph device in which first and second piezoelectric ceramic layers are so electrically connected to each other as to expand or contract in the opposite directions, which is characterized in that when t.sub.1 is taken as the thickness of one of the first and second piezoelectric ceramic layers, Ec is taken as the coercive field strength of a piezoelectric material constituting the piezoelectric ceramic layer, and V.sub.1 is taken as the minimum value of the produce Ec.times.t.sub.1 =Vc.sub.1, and t.sub.2 is taken as the thickness of the other piezoelectric ceramic layer, Ec is taken as the coercive field strength Ec of a piezoelectric material constituting the piezoelectric ceramic layer, and V.sub.2 is taken as the minimum value of the produce Ec.times.t.sub.2 =Vc.sub.2, a voltage of not less than (V.sub.1 +V.sub.2) is applied to said piezoelectric bimorph device.

Abstract: A piezoelectric filter device of an energy-trapped type utilizing a higher harmonic in the thickness-extensional vibration mode, having a plate-shaped body made of a piezoelectric material. At least three electrodes are arranged so as to overlap each other while being separated by layers of the piezoelectric material in the direction of thickness of the plate-shaped body. At least one of the electrodes comprises a plurality of divided electrodes which are substantially coplanar. At least one of the divided edlectrodes constitutes an input terminal and at least one of the remaining divided electrodes constitutes an output terminal. A region of the body, around the vibrating region, where the electrodes are overlapped with each other, is uniformly subjected to polarization processing in the direction of thickness.

Abstract: Disclosed is an energy-trapping-by-frequency-lowering-type piezoelectric-resonance device utilizing a higher harmonic in the mode of thickness-extensional vibration, in which at least three electrodes for energy trapping are arranged so as to be overlapped with each other in the direction of thickness of layers of piezoelectric material forming a plate-shaped body. The three electrodes comprise a pair of outermost electrodes and at least one inner electrode. The diameter of one polygonal side of at least one outermost electrode is made larger than the diameter of one polygonal side of an inner electrode.

Abstract: An energy trapping type piezoelectric resonance device utilizing higher-order harmonics of the thickness extensional vibration mode comprising a body formed of a piezoelectric material and three or more electrodes arranged overlapping with each other and separated by the piezoelectric material layers in the direction of thickness of the body, wherein respective portions of the piezoelectric material layers interposed between the electrodes are polarized and at least respective portions of the piezoelectric material layers which are not interposed between the electrodes is polarized.

Abstract: A piezoelectric resonance device of the energy-trapped type utilizing a harmonic wave of the thickness extensional vibration mode, wherein three or more electrodes are so disposed that they are overlapped with each other through the piezoelectric layer in the direction of the thickness and each of the electrodes is comprised of a vibrating electrode portion for energy-trapping and a conducting portion for connecting the vibrating electrode to the side edge of the piezoelectric layer.

Abstract: An energy trapping type piezoelectric resonance device utilizing the mode of thickness extensional vibration comprises a plate-shaped body of a piezoelectric material and three or more electrodes provided to be opposed to each other through peizoelectric material layers in the direction of thickness of the body. At least one of the electrodes is provided to be smaller in area than the major surfaces of the body, to be capable of energy trapping.

Abstract: A chip type piezoelectric device includes an element body formed of cofired ceramic material and having at least a pair of excitation electrodes opposed to each other with a portion of the element body interposed therebetween. At least the portion interposed between the excitation electrodes has piezoelectricity imparted thereto, whereby this portion serves as a vibrating portion. Of the pair of excitation electrodes at least one excitation electrode is positioned in the interior of the element body, and the element body is formed with a cavity only on the side of this interiorly positioned excitation electrode away from the vibrating portion.

Abstract: Piezoelectric ceramic compositions comprising a principal component, ##EQU1## and manganese contained therein as an additive in the amount of 0.1 to 2.0 wt % of MnO.sub.2 with respect to the weight of 1 mol of the principal component. The piezoelectric ceramic compositions are suitable for use for pyroelectric devices, piezoelectric vibrators, resonators, oscillators, ceramic filters, surface acoustic wave filters and so on.

Abstract: A piezoelectric ceramic composition comprises a major component, ##STR1## (where 0.01.ltoreq.X.ltoreq.0.40 and 0.ltoreq..alpha..ltoreq.1), and CuO contained therein as an additive in an amount of 0.05 to 2.5 wt % with respect to the weight of 1 mole of the major component. If required, this composition may contain 0.05 to 2.0 wt % of MnO.sub.2 with respect to the weight of 1 mole of the major component. The composition has excellent temperature characteristics in addition to excellent dielectric and piezoelectric characteristics suitable for use in various fields.