Reduced Dielectric Loss and Strain Hysteresis in Fe and Mn Comodified High-Temperature BiScO_3-PbTiO_3 Ceramics

摘要

There is a growing requirement for high-temperature piezoelectric materials in the petrochemical, automotive, and aerospace industries. Here, the piezoelectric materials of Fe and Mn comodified 0.36BiScO_3-0.64PbTiO_3 (BS-PTFMn) ceramics with high Curie temperature (T_c), large mechanical quality factor (Q_m), and reduced strain hysteresis were presented. XRD results revealed that all the BS-PTFMn ceramics have a pure perovskite structure with tetragonal symmetry, and the ratio of c/a is insensitive to the contents of Fe. With the modifications of Fe, the dielectric loss tanδ and strain hysteresis decrease clearly, while the mechanical quality factor improves significantly. The Curie temperature, piezoelectric constant, planar electromechanical coupling factor, dielectric loss, and mechanical quality factor of the BS-PTFMn with 3% Fe content are 492℃, 235 pC/N, 0.38, 0.6%, and 280, respectively. BS-PTFMn ceramics show 50℃ higher T_c than BS-PT morpho-tropic phase boundary composition. The figure of merit (product of Q_m, ε_(ij)~T and k_(ij)) of BS-PTFMn ceramics is about five times than that of pure BS-PT ceramics. Furthermore, for the BS-PTFMn ceramics with Fe content of 3 mol%, the high field strain coefficient d_(33)~* value calculated from the electric-field-induced strain curves (S_(max)/E_(max)) is 320 pm/V, while the strain hysteresis (under 40 kV/cm) is reduced to one fifth that of unmodified BS-PT ceramics. Moreover, the temperature-dependent electromechanical coupling coefficient and dielectric constant are very stable in the temperature range from room temperature (RT) to 450℃. These results indicated that BS-PTFMn ceramics are promising for high-temperature piezoelectric applications.