Lead-free piezoelectric ceramic composition wherein Cu is contained in (KxA1-x)y(Nb1-zBz)O3 perovskite compound, and process of preparing the same

摘要

A lead-free piezoelectric ceramic composition wherein a suitable amount of Cu is contained in a perovskite compound of a non-stoichiometric composition represented by a formula (K_xA_1−x)_y(Nb_1−zB_z)O₃, wherein “A” represents at least one of Na and Bi, while “B” represents at least one of Ta and Ti, and wherein 0x≦1, 0y1, and 0≦z≦1, so that by-products such as K_aCu_bNb_cO_d and K_aCu_bTa_cO_d are produced as a result of reaction of (Nb_1−zB_z) with Cu in the process of calcination of a starting material, and the by-products restrict melting and abnormal grain growth of (K_xNa1-_x)(Nb_1−zTa_z) O₃ during firing of a calcined body, thereby improving sinterability of the fired body, while restricting volatilization of alkali components and melting of KNbO₃, thereby increasing the density and improving the piezoelectric properties of the fired body. The ceramic composition is prepared by firing a starting composition including the perovskite composition as a primary component, and a secondary component in the form of at least one of compounds K_aCu_bNb_cO_d, K_eCu_fTa_gO_h and K_iCu_jTi_kO_l.