The Investigation of the Elastic and Piezoelectric Properties of SrHfO3 and the Effect of Uniaxial Stress on its Piezoelectric Properties: an ab initio study

The basic principles of calculations in the framework of density functional theory and density functional perturbation theory were used to investigate the elastic and piezoelectric properties of hypothetical SrHfO3 compound in tetragonal structure with P4mm space group. Polarization and Born effective charges tensor were calculated to investigate the nature of ferro-electricity of this system in an atomic scale. Our results show that Born effective charges of both Hf and O atoms are much larger than their anticipated nominal charges which show a strong bonding between Hf and O atoms. Formation energy calculation revealed that the compound will be stable, if it is synthesized and would not decompose to its ingredients. Non-vanishing and significant calculated piezoelectric constants imply system piezoelectricity. The effect of uniaxial stress along the c-axis on polarization, Born effective charges and piezoelectric stress and strain coefficients were also investigated. We found that the polarization increases as the uniaxial stress goes from negative to positive. These changes suggest that the uniaxial tensile stress could raise the ferro-electricity, 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.