Abstract: A semichemical method (SCM) was developed for synthesizing 0.80Pb(Mg_1/3Nb_2/3)O₃-0.20PbTiO₃ (PMNT) with pure perovskite phase. The influences of the chemical reactivities of the
partial starting materials, such as soluble Mg-salts instead of MgO, Pb-salts instead of PbO and Ti(OC₄H₉)₄ instead of TiO₂ and crystalline of pure perovskite phase of PMNT on the formation of perovskite
phase were investigated in detail. The influences of technological parameters, such as calcining temperature, sintering temperature and soaking time, on the phase content, and dielectric properties were investigated
systematically. The results show that Mg-salts are effective for the formation of perovskite phase, especially Mg(NO₃)₂ and/or Mg(AC)₂ instead of MgO in a molecular grade. Almost pure perovskite
phase can be obtained by both using Mg(NO₃)₂ and Ti(C₄H₉O)4 instead of MgO and TiO₂ respectively. The optimum preparation parameters are the calcining condition of 850℃/2h
and the sintering condition of 950℃/2h. The semichemical method has many advantages of not only simple preparation process, lowing calcining and sintering temperatures, shorting reacting time,
but also preparing ceramics with excellent dielectric properties. The sintered ceramics having clear crystal boundaries, large-sized crystal grains and high density, and pure perovskite phase of PMNT
were successfully prepared by the SCM.

Key words: semichemica] method, relaxor ferroelectrics, perovskite phase, dielectric properties