PbNi_<1/3>Nb_<2/3>O_3-PbTiO_3-PbZrO_3系セラミックスの圧電及び強誘電特性に及ぼすMnO_2添加の影響

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High-density 0.5PbNi_<1/3>Nb_<2/3>O_3・0.345PbTiO_3・0.155PbZrO_3(0.5PNN・0.345PT・0.155PZ)ceramics were prepared by normal sintering with the addition of 0-3.66 mol% MnO_2 and their piezoelectric and ferroelectric properties were investigated. The effect of MnO_2 addition on significantly lowering the value of tan δ in the range of 0.37 to 0.93 mol% was proven. The lowest value (=0.37%) of tan δ was obtained in ceramics with 0.75 mol% MnO_2. Electromechanical coupling factors, k_p and k_<31>, and the piezoelectric constant, d_<31>, decreased with increasing amount of MnO_2 addition. The highest values of k_p, k_<31> and d_<31> were 0.66, 0.38 and -362 pC/N, respectively, and were obtained in the ceramics without MnO_2. The effect of MnO_2 addition on improving the value of the mechanical quality factor, Q_m, was proven in the range of 0.93 to 1.85 mol% and the improvement was around twenty times that of the sample without MnO_2. The distortion in the shape of P-E hysteresis loops for samples with MnO_2 addition suggested that oxygen vacancies formed by substituting Mn^<3+> ions for B-site ions (e.g., Ti^<4+> and Zr^<4+> ions) in the perovskite structure partially inhibited the polarization reversal in the ferroelectrics. 0.5PNN・0.345PT・0.155PZ ceramics with 0.75-0.93 mol% MnO_2 show great promise as practical materials for piezoelectric applications.
社団法人日本セラミックス協会の論文
2000-07-01