X-ray diffraction pattern and SEM image obtained from the CCTO dense ceramic.
(Color online) Capacitance versus dc-voltage curves, C-V, at 10 kHz and different temperatures.
(Color online) Blow-ups of C-V for the temperatures 288 K, 230 K, 200 K and 150 K. (a) 10 kHz and (b) 20 Hz.
(Color online) Capacitance versus ac-voltage curves, C(Vac) at 2 kHz and 420 K. The inset shows the radius of the impedance semicircles under different ac voltage loads.
The C-V curves sometimes shows large jumps and a large hysteresis under repetitive measurements V−→ 0→ V+→ 0 → V.
Sketch of a back to back Schottky barrier with symmetric space charges.
Sketch of the repositioning of trap charges between one field perpendicular (fs) boundary and two field parallel (fp) boundaries under an ac-voltage. The regions without shadow represent the boundaries containing anisotropic center multipole charges. Numbers “1” and “2” of the ellipsoids indicate two different positions of the multipoles (charge +dipole) which can switch under the influence of an electrical field (dc or ac)
(Color online) Comparison of the capacitance after a long relaxation out of the compensated electrical conditioning state C∞, and the capacitance C (V = 0) for different temperatures. Both should depend on the ± dipole polarization ratio. The inset shows two examples of the creep functions.
(Color online) Three types of C-V –curves which differ in their +/− polarization ratio evolution during repositioning. Set B = 4αUc 2 /kTd2 = 1, and v = U/Uc = 0∼2, γ1 = 0 and γ1 = +1/Uc and γ1 = −1/Uc, (see Eq. (11)). The arrows indicate the possibility of a first order electrical field induced transition between two different matrix electronic phases, supplying different polarization ratio evolutions (see butterfly curve).
(Color online) Fitting of the C-V curves at 10 kHz and several temperatures according to Eq. (12) in an attempt to extract the polarisability α.
The parameters at several temperatures according to the simulation.
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