Effects of Sm-substitution on dielectric, ferroelectric, and piezoelectric properties of 0.36(Bi1-xSmx)ScO3-0.64PbTiO3 ceramics

Dielectric, ferroelectric, and piezoelectric properties of 0.36(Bi1-xSmx)ScO3-0.64PbTiO3 (BSPT-xSm) ceramics were investigated to assess effects of Sm-substitution on 0.36BiScO3-0.64PbTiO3 for high temperature piezo-electric device application. Optimal sintering was achieved at 1200 degrees C when the BSPT-xSm ceramics were fully densified and crystallized with a perovskite structure without any secondary phase. The substitution of Bi3+ with Sm resulted in degradation of rhombohedral side in BSPT-xSm ceramics having morphotropic phase boundary. In addition, variations of grain size and ferroelectric behavior after Sm-substitution were insignificant. However, dielectric constant (epsilon T33/epsilon 0) was significantly enhanced with an increasing of amount of Sm to 5%. Although a slight decrease of relative density in case of x exceeding 3% led to deterioration of piezoelectric values of d33, kp, and d33*, the BSPT-3%Sm ceramic exhibited excellent values of d33 of 628 pC/N, kp of 62.4%, and d33* of 718 pm/V at 4.5 kV/mm, along with a high ferroelectric transition temperature of 421 degrees C. The highly increased diffusion coefficient of 1.909 also implies that the Sm-substitution contributed to relaxor-like ferroelectric behavior of BSPT ceramics.