PbTiO_3系セラミックスにおける圧電特性の組織依存性 : 物性・応用

概要

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The grain size dependence of lattice constants (a and c) , dielectric constant (ε/ε_θ), dissipation factor (tan δ) , electromechanical coupling factors (k_t and k_p) , and mechanical quality factor (Q_M) was investigated in ceramics with the compositions of 0.99・Pb_<1-x>La_<2x/3>TiO_3 + 0.01・MnO_2 with X = 0. 05 (grain size = 0. 37-1.32μm) and X = 0.10 (grain size = 0.30-1.14μm). With decreasing grain size, c/a (lattice constant ratio), tan δ (of non-poled) , k_t/k_p. (anisotropy of coupling factor) , and Q_M decreased, while ε/ε_θ (of both non-poled and poled) increased. When poled tan δshowed little grain size dependence. A close correlation was observed between the lattice constant ratio and the dielectric constant for all the materials, and the grain size dependence of these properties has been attributed mainly to the effect of internal stress in grains. The grain size dependence of tanδmay be interpreted on the basis of the effect of grain size on the motion of domain boundaries. The values of Q_M^<-1> and tan δ did not agree with the relationship, Q_M^<-1> ∝ tan δ, usually observed in ferroelectric materials. This is possibly explained in terms of the ceramic structure-dependent component of inner friction (Q_M^<-1>) , which becomes significant with decreasing grain size.
社団法人日本セラミックス協会の論文
1990-08-01