Piezoelectric ceramic material for forming a sintered compact used in the manufacture of piezoelectric devices, such as wave filters and oscillators, comprises a solid solution of a specified crystalline tetragonal system

摘要

Piezoelectric ceramic material (3) comprises a solid solution of a crystalline tetragonal system comprising a primary component of PbTiO3, PbZrO3 and Pb(Ma(x)Md(y))O3 in which up to 20 mol % of Pb is replaced by Ca, Ba, Sr and/or La, Ma is a di- or tri-valent element, and Md is a penta- or hexa-valent element. The ratio of the contents of Ma (x) and Md (y), x/y, is above the stoichiometric ratio. Preferred Features: Ma is preferably manganese (Mn). Md is preferably selected from Nb, Sb, Ta and W. The molar percentage contents of Mn, Nb, Sb, Ta and W, represented respectively by A, B, C, D and E satisfy the condition: A/(B+C+D+2E) = 0.525-1. More than 0 molar %, preferably 1-4 molar %, of Pb in the piezoelectric ceramic composition is replaced by Ca, Ba, Sr and/or La. The material can also contain 0.003-0.1 parts weight SiO2 and 0.003-0.1 parts weight Al2O3 per 100 parts weight of the primary composition. Independent claims are given for: (a) a sintered piezoelectric ceramic compact obtained by sintering the above material in an atmosphere containing at least around 80% oxygen; and (b) a piezoelectric ceramic device comprising the sintered piezoelectric ceramic and surface electrodes (4, 5).