Abnormal ferroelectric response and enhancement of piezoelectricity of PbTiO3 under uniaxial compression.

The ferroelectricity of rhombohedral PbTiO₃ under uniaxial compression is investigated from first-principles study. Upon compression, the ferroelectricity decreases until a critical stress of -29 GPa and then increases with a further increase of the magnitude of the uniaxial compressive stress. We also find that uniaxial compression could enhance piezoelectricity and that the maximum piezoelectric coefficient d₃₃ occurs at σ₃₃=-49 GPa, which supports the experimentally observed piezoelectric behavior in rhombohedral Pb(Mg_1/3Nb_2/3O₃)-0.32PbTiO₃ [Q. Wan, C. Chen, and Y. P. Shen, J. Appl. Phys. 98, 024103 (2005)]. Our calculated results show that the Pb, Ti, and O atoms have different contributions to the total polarization with increasing the magnitude of uniaxial compressive stress, and that when -σ₃₃>55 GPa, the Ti atoms no longer have contributions to the polarization, which leads to the changes of ferroelectricity and piezoelectricity. [ABSTRACT FROM AUTHOR]