Phase separation inLa2CuO4+yceramics probed by dielectric measurements

Dielectric properties of La1.75Ba0.25NiO4 ceramics prepared by spark plasma sintering

“…There are two types of non-stoichiometric oxygen defects that can be existed in the present ceramics, one is the interstitial oxygen and the other is lattice oxygen vacancy. The removal of the interstitial oxygen will decrease the electrical conductivity of the sample, while the creation of lattice oxygen vacancy will increase the electrical conductivity of the sample [17,18]. So, we conclude that the low electrical conductivity of spark plasma-sintered sample should be resulted from the extraction the interstitial oxygen from the sample during the sintering process.…”

“…Actually it is difficult to prepare the stoichiometric ceramics by the conventional solidstate sintering process in air due to the capability of K 2 NiF 4 -type arrangements for accommodating extra oxygen in the interstitials of the structure [15,16]. The extra interstitial oxygen will increase the conductivity of the sample [17,18], and this will deteriorate the * Corresponding author. Tel.…”

Dielectric response of Al-substituted multiferroic TbMnO3 at high temperatures

“…Hence another kind of energy dissipation mechanism arising from "relaxation" first comes into play in the high-frequency range. It is to be expected that at temperatures below 300 K the deviation from the straight line will be more pronounced, which would allow identifying two different regimes, namely a low-frequency dissipation regime related to charge transport, and the relaxation regime, active at higher frequencies and originating from the relaxation of condensed clusters [31]. It is widely known that impedance analysis is a powerful technique often used to separate different dielectric relaxations stemming from the intragrains, intergrains, and electrodes of ceramic materials [32].…”

“…It is probable that some microdomains (containing small polarized clusters) exist even at such high temperatures. The slow dynamics of the domain walls in these microdomains may contribute to the delay of the response to the external alternating field, particularly at high frequencies [31]. Hence another kind of energy dissipation mechanism arising from "relaxation" first comes into play in the high-frequency range.…”

Dielectric properties of spinel ceramic Fe1.8V1.2O4

“…The Arrhenius plot of lnf vs. 1/T p shows a linear behavior (inset of Figure 1(a)) with activation energy E g of 107.5 meV. The dielectric plateaus as well as the great drop in between at low temperatures were widely observed in transition metal oxides [6][7][8][9], which is usually ascribed to the Maxwell-Wagner type dielectric relaxation due to the electric conduction inhomogeneity in the matrix, at grain boundary (GB) or at the electrode-sample interface (EI) [10,11]. In our case, the electrode contacts are ohmic.…”