Electro-optic properties of ZrO2, HfO2, and LiNbO3 ferroelectric phases: A comparative density functional study

We report the Pockels electro-optic properties of ZrO2 and HfO2 orthorhombic Pbc21 and rhombohedral R3m ferroelectric phases, and we compare them to the well-known rhombohedral R3c LiNbO3 Pockels material from density functional theory calculations using the CRYSTAL suite of programs. Specifically, three essential processes are explicitly investigated: The electronic, the ionic (or vibrational), and the piezoelectric contributions. Our calculations reveal that the ionic part coming from the low-frequency phonon modes contributes the most to the electro-optic coefficients of rhombohedral LiNbO3 and of orthorhombic ZrO2 and HfO2. Additionally, the low -frequency phonon modes exhibit zero contribution to the Pockels coefficients of ZrO2 and HfO2 rhombohedral R3m phase.