Low Loss Lead Zirconate-Titanate Ceramics

Abstract

To improve the mechanical Q of lead zirconate-titanate: Pb(Zr-Ti)O₃ ceramics, several effects of additions in small quantity were investigated. As additions, ZnO ; Al₂O₃ In₂O₃, Ga₂O₃ ; NaOH, KOH and RbOH are selected in consideration of their ionic radii and valencies. The results obtained are as follows :
(1) The fine grain structure is obtained by and of these additions except RbOH and the high density is attained in all cases.
(2) The mechanical Q is extremely improved within the limit of the additions of 0.5-1mol%.
(3) Zn²⁺, Al³⁺, In³⁺ and Ga³⁺ seem to replace the Zr⁴⁺-Ti⁴⁺ ions and Na⁺, K and Rb²⁺ the Pb²⁺-Sr²⁺+ ions, viewed from the amount of PbO absorption and ionic radii.
(4) An addition of In₂O₃, ZnO or NaOH sifts the morphotropic phase boundary toward the Ti excess site to some extent.
(5) Assuming that these metallic ions replaced Pb²⁺-Sr²⁺ or Zn⁴⁺-Ti⁴⁺ sites create an oxygenvacancy which is frozen at room temperature, this vacancy will induce an anisotropy. Consequently, it seems that by this induced anisotropy a motion of 90° wall is prevented, and mechanical Q is reduced.