Dielectric relaxations in SrTiO3 doped with La2O3 and MnO2 at low temperatures

Oxygen-vacancy-related dielectric anomalies in La:SrTiO3

“…3͑a͔͒ was previously recognized as due to Ti ions hopping according to Skanavi's model. 11,13,14 However, in the present work, the intensity of this set of permittivity peaks is further decreased after Ann. 3 ͓Fig.…”

“…For example, one set of permittivity peaks with very high peak values (⑀ max Ј ϭ5000 and tan ␦ max ϭϳ0.15, at 40 kHz͒ was observed between 110 and 290 K for (Sr 1Ϫ3x/2 La x )TiO 3 with xϭ0.014, 14 however, early work reported that in this temperature range, the highest permittivity value was lower than 700 at 10 kHz and no permittivity anomalies occurred for La content less than xϭ0.067. 10 These contradictory results cast some doubt on the previous explanations for the dielectric relaxation in La or other REdoped ST in term of Skanavi's model, and particularly whether the relaxor species is really Ti 4ϩ ions.…”

Dielectric relaxation behaviour of Sr 2 SbMnO 6 ceramics fabricated from nanocrystalline powders prepared by molten salt synthesis

“…The fit parameters obtained for the impedance data at 250 K (figure 6(c)) such as (R g , R gb ), (A g , A gb ) and (β g , β gb ) representing the resistive and capacitive elements associated with the high and low frequency grain and grain boundary dielectric response, are listed in table 2. The A g value is characteristic of other bulk ferroelectrics and the A gb value reveals that the sample is well sintered, with narrow intergranular regions (Iguchi and Lee 1993). The calculated A g and A gb values are also consistent with the measured values in dielectric spectroscopy.…”

“…The relaxation parameters, E II = 0·35 (2) eV, τ 0II = 3·2 × 10 −10 s, for the P DII peak ( figure 4(a)), and E I = 0·26 (2) eV, τ 0I = 4·01 × 10 −11 s for the P DI peak ( figure 4(b)) are obtained. The activation energy of 0·26 eV has been reported to be equivalent to the activation energy required for the thermal motion of Mn 3+ cations within the oxygen octahedra (Iguchi and Lee 1993).…”

Dielectric relaxation and conduction mechanism in LaNi3/4M1/4O3 (M=Mo, W) at low temperature

“…In the literature, the dielectric relaxation with extremely high permittivity has been reported in many materials, in which the contribution of conduction carriers (electrons, holes, ions, polarons and protons) to dielectric polarization may play an important role. However, the explanation of this phenomenon is controversial based on different models [2][3][4][5]. The electron localized on an ion (or a few ions) can cause displacements of neighbouring ions from their positions in the crystal lattice.…”