Electro-optic evolution driven by static and relaxational nano ferroelectric domains in KTa1−xNbxO3†
Polar nano-regions (PNRs), whose evolution and response mechanism are unclear, were identified to be responsible for the pivotal large electro-optic (EO) coefficients near the TC in KTa1−xNbxO3 (KTN) crystals. To investigate this phenomenon, the temperature dependence of its Raman spectrum, and of its linear effective and quadratic EO coefficients, were investigated. Our results showed that both the relaxational nano-domains driven by biased electric fields under ordered static domains and strong anisotropy determined by the deformation of the NbO6/TaO6 realize enhancements of EO properties in the vicinity of Tf. We expect this understanding of the dynamic EO characteristics to be valuable for developing photonic devices and for providing a basis for exploring the origin of giant EO and piezoelectric effects in disordered ferroelectrics and relaxors.