EFFECT OF B-IONS SUBSTITUTION IN [(K1 2BI1/2)-(NA1/2BI1/2)](TI-B)O-3 SYSTEM WITH B=ZR,FE1/2NB1/2, ZN1/3NB2/3 OR MG1/3NB2/3/

Phase relationship in the [(K1/2Bi1/2)(1-y)(Na1/2Bi1/2)(y)](Ti1-xBx)O- 3 system with B = Zr, Fe1/2Nb1/2, Zn1/3Nb2-3 or Mg1/3Nb2/3 has been in vestigated by dielectric measurement and X-ray diffractometry, All of the bi-binary systems were solid-soluble throughout the entire composi tion range. With increasing y and x, ferroelectric Curie point decreas ed and the epsilon-T curve became flat. Composition dependence of the transition temperature was examined by varying x or y. Phase diagrams were mostly determined at room temperature on square diagrams except f or a restricted area in the vicinity of (Na1/2B1/2)ZrO3, which involve d a tetragonally distorted phase and could not be accounted for. The f erroelectric tetragonal phase was confined within a narrow range of a x<0.1 and thr rhombohedral phase was dominant in all of the systems st udied here.