Enhancement of piezoelectricity of tetragonal P4mm SrHfO3 under uniaxial stress: A first principle study

First principle calculations in the framework of density functional theory and density functional perturbation theory within the generalized gradient approximation are used to calculate the ground state polarization, Born effective charges and piezoelectric strain constant d33 of hypothetical tetragonal P4mm SrHfO3. Our results predict the occurrence of piezoelectricity in this hypothetical system. Born effective charges of both Hf and O atoms are much larger than their anticipated nominal charges which show a strong hybridization between Hf and O atomic orbitals. The effect of uniaxial stress along the c-axis on polarization, Born effective charges and piezoelectric strain coefficient d33 are also studied. We found that the polarization will increase as the uniaxial stress raises from negative to positive values. These changes suggest that the uniaxial tensile stress could raise the ferroelectricity, while the uniaxial compressive stress would cancel it. We also found that the piezoelectricity of this system could be improved by applying stress. These results could be significant in the field of lead free piezoelectric materials.