Simultaneously improving piezoelectricity and temperature stability of 0.05Pb(Yb 1/2 Nb 1/2 )O 3 –0.95Pb(Hf 0.45 Ti 0.55 )O 3 ceramics by Sr 2+ substitution

In this study, Sr 2+ -modified polycrystalline 0.05Pb(Yb 1/2 Nb 1/2 )O 3 –0.95Pb(Hf 0.45 Ti 0.55 )O 3 (PYN-PHT) ceramics have been fabricated via traditional solid-phase sinterting. Further analysis of micro-structural evolution was carried out by X-ray diffraction adopting Rietveld refinement approach. The thermal tolerance capability, ferroelectric, piezoelectric, and dielectric performance of the ceramics were investigated systematically as well. The results reveals that tetragonal perovskite phase content decreased with the increase of Sr 2+ substitution content. The decline of tetragonality ( c / a ) leads to the twist of oxygen octahedrons and unit cell shrinkage in perovskite structure. The lattice distortion is conducive to increase lattice free energy, thus improving the bulk density and grain size of the PYN-PHT samples. Rayleigh analysis shows that Sr 2+ -modified PYN-PHT ceramics improved the external and internal contributions of piezoelectric response, resulting in more rhombohedral phases and greater strain. When the Sr 2+ content is 0.6 mol% and the sintering temperature is 1175 °C, the piezoelectric coefficient, Curie temperature, electromechanical coupling coefficient, dielectric constant and dielectric loss all got to notable values, i.e., d 33 = 550 pC/N, T c = 335 °C, k p = 0.65, ε r = 2614, and tan δ = 1.4%. It is worth mentioning that, when test ambient temperature reached 300 °C, the d 33 value remains at 526 pC/N. These results indicate that Sr 2+ -modified PYN-PHT ceramics have potential competitiveness in high temperature applications.