Studies of tetragonal PbTiO3 subjected to uniaxial stress along thec-axis

Abstract

Tetragonal PbTiO3 underuniaxial stress along the c-axis is investigated from first-principles. The structural parameters,polarization, and squares of the lowest optical phonon frequencies forE(1TO) andA1(1TO) modes atΓ show abruptchanges near a stress σc of 1.04 GPa, which is related to the dramatic change of elastic constantc33 resulting from the uniaxial stress applied along thec-axis. We also find that the uniaxial compressive stress could enhance the piezoelectricstress coefficients, whereas the uniaxial tensile stress could enhance the piezoelectric straincoefficients. It is also found that when the magnitude of uniaxial compressive stressσ33 is greaterthan 12 GPa, PbTiO3 is transformed to the paraelectric tetragonal phase.