Effect of Molecular Mass of B-site Ions on Electromechanical Coupling Factors of Lead-Based Perovskite Piezoelectric Materials

Abstract

The effects of the molecular mass of B-site ions of Pb(B ′ B ′′ )O 3 –PbTiO 3 (B ′ =Mg, Zn, Ni, Sc, In and Yb; B ′′ =Nb and Ta) and Pb(B, Ti)O 3 (B=Zr, Hf and Sn) piezoelectric materials on the electromechanical coupling factors were investigated. The relationship between the electromechanical coupling factor k p near a morphotropic phase boundary (MPB) and the molecular mass of B-site ions is systematically discussed. The reason why k p of Pb(Zr, Ti)O 3 (PZT) is larger than that of Pb(Hf, Ti)O 3 (PHT) or Pb(Sn, Ti)O 3 (PST) is explained in terms of the molecular mass difference between A-site and B-site ions of Pb(B, Ti)O 3 . It may be concluded that a combination of the B-site ions which have a lower molecular mass in MPB composition, play an important role in realizing large electromechanical coupling factors in lead-based perovskites. From this viewpoint, MPB compositions of Pb[(Sc 1/2 Nb 1/2 ) 0.58 Ti 0.42 ]O 3 (PSNT 58/42), which has the largest molecular mass difference between A-site and B-site (Amass-Bmass=147.1) ions may be the best combinations of all Pb(B ′ B ′′ )O 3 –PbTiO 3 and Pb(B, Ti)O 3 systems so far reported. However, if Pb[(Al 1/2 Nb 1/2 ) 1- x Ti x ]O 3 and Pb[(Ga 1/2 Nb 1/2 ) 1- x Ti x ]O 3 systems can be synthesized into pure perovskite structures near the MPB, a better piezoelectric performance than PZT 53/47 or PSNT 58/42 is expected.