Ceramic composition with improved electrical and mechanical properties

A ceramic composition consisting essentially of a solid solution of (a) the ternary system consisting essentially of lead magnesium-niobate (Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3), lead nickel-niobate (Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3) and lead titanate (PbTiO.sub.3) as a major constituent, and (b) an additional constituent consisting essentially of lead manganese-niobate (Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3) in a proportion of about 0.01 to about 10 mol% to said major constituent, said ternary system being expressed by the general empirical formula [Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 ].sub.x -[Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3 ].sub.y -[PbTiO.sub.3 ].sub.z wherein the subscripts x, y and z satisfy the equation x+y+z=1 and fall within the region defined by the line segments joining the seven points C, A, B, D, E, F and G which are given by the coordinates

• A (x=0.10, y=0.70, z=0.20),
• B (x=0.15, y=0.60, z=0.25),
• C (x=0.15, y=0.70, z=0.15),
• D (x=0.40, y=0.35, z=0.25),
• E (x=0.60, y=0.20, z=0.20),
• F (x=0.70, y=0.20, z=0.10), and
• G (x=0.50, y=0.40, z=0.10),
• on the triangular ternary-system diagram shown in the accompanying drawing.