Abstract: The present invention provides a piezoelectric ceramic having a low mechanical quality coefficient Qm and excellent heat resistance, for example, a piezoelectric ceramic for a filter element which can be applied to surface mounting. The piezoelectric ceramic contains at least a composite oxide of lead, zirconium and titanium, and oxides of manganese, silicon and boron, the concentration of the manganese oxide present in the crystal gain boundary being higher than that in crystal grains of the piezoelectric ceramic.

Abstract: There is provided a piezoelectric ceramic having a small mechanical factor of merit Qm and excellent heat-resisting properties, e.g., a piezoelectric ceramic for filter elements which is compatible with surface mounting and a method of manufacturing the same in a large amount and in a stable manner. There is provided a piezoelectric ceramic which is a composite oxide of at least lead, zirconium and titanium, wherein an oxide of manganese exists in a grain boundary layer in a density higher than that in a crystal grain of the piezoelectric ceramic and a glass phase exists in the grain boundary layer. It is manufactured by depositing a manganese compound and a glass material on the surface of a piezoelectric ceramic comprising a composite oxide of at least lead, zirconium and titanium and by performing thermal processing thereafter to diffuse the deposited substance in a grain boundary portion of the piezoelectric ceramic.

Abstract: A three-component piezoelectric ceramic composition having a large electro-mechanical coupling coefficient and high mechanical strength, composed of xPb(Mg.sub.w/3 Nb.sub.1-w/3)O.sub.3 -yPbZrO.sub.3 -zPbTiO.sub.3, is adapted so as to place points representing the compositional proportions x, y, and z (x+y+z=1) on lines connecting pointsA: (x=0.70, y=0.01, z=0.29),B: (x=0.50, y=0.01, z=0.49),C: (x=0.05, y=0.40, z=0.55), andD: (x=0.05, y=0.65, z=0.30)and in the compositional region bounded by the lines in a three-component composition diagram and the value of w in the range from 0.8 to 1.

Abstract: Piezoelectric ceramics whose mechanical quality factor Qm is small and which has an excellent heat resistance, e.g. piezoelectric ceramics for filtering elements whose group delay time characteristic is flat, phase distortion is small and which can be accommodated to surface mounting, and a method for stably producing it are provided. Manganese oxide and lead oxide are caused to coexist in high concentration in grain boundary parts of the piezoelectric ceramics containing composite oxides of at least lead, zirconium and titanium as compared to intra-crystal grains of the piezoelectric ceramics. It is manufactured by treating the piezoelectric ceramics by heat after adhering manganese and lead compounds on the surface thereof to diffuse the oxides in the grain boundary parts of the piezoelectric ceramics.

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.