Normal and abnormal dielectric relaxation behavior in KTaO₃ ceramics

Abstract

KTaO3 ceramic samples were prepared via a conventional solid state reaction route.

Microstructure, colossal permittivity, and humidity sensitivity of (Na, Nb) co‐doped rutile TiO2 ceramics

“…Linear fitting yields the activation energy value of 0.57 eV. This value is comparable with the activation energy of the Maxwell‐Wagner relaxation caused by surface‐layer effect in various oxides due to water absorption . To confirm the Maxwell‐Wagner nature of the 250 K‐relaxation, Figure B shows the complex impedance spectra of the NNTO‐2 ceramic at room temperature under various dc biases.…”

Maxwell-Wagner Relaxations in Ca-, Sm- and Nd-doped Ceria

“…From which one notes that the activation energy for R1 and R2 lies between 0.6-1.2 eV. This binding energy is for the dielectric relaxation caused by thermally activated migration of oxygen vacancies [20][21][22][23][24]. Besides, the Arrhenius plot of CCO exhibits two-segment nature.…”

“…The low-T segment shows an activation energy of 1.05 eV, whereas the high-T one shows a much lower activation energy of 0.60 eV. This feature is a hallmark of oxygen vacancies transforming form hopping conduction to band conduction [20].…”

Collective nonlinear electric polarization via defect-driven local symmetry breaking

“…Instead, the only reasonable model found is to combine both Debye-like and non-Debyelike relaxation as proposed by Mocedo et al 30 , originally to treat the relative roles of free and activation energy in the viscosity of liquids. The model considers that the relaxation acts as an occurrence of two simultaneous events: the "molecule" must attain sufficient energy to break away from its neighbors and change its orientation, and there also must be a site with a defect in the vicinity of the moving "molecule" with sufficient local free volume for a reorientation to occur [31][32][33] . Here we adapt this model to treat the reorientation of the oxygen vacancy to transform the defect as analogous to the defect formation in the model of Mocedo et al et al 30 with the corresponding reordering of the lattice distortion taking the role of molecular reorientation.…”

“…Based on these insights and the results of the DFT calculations described below, we suggested a relation where both reorientation of defect-dipoles and associated simultaneous defect transitions are considered (see Supplementary Information Section II for details) [31][32][33] :…”