Colossal dielectric behavior of semiconducting Sr2TiMnO6 ceramics

Abstract

Manganitelike double perovskite Sr2TiMnO6 (STMO) ceramics fabricated from the powders synthesized via the solid-state reaction route, exhibited dielectric constants as high as ∼105 in the low frequency range (100 Hz–10 kHz) at room temperature. The Maxwell–Wagner type of relaxation mechanism was found to be more appropriate to rationalize such high dielectric constant values akin to that observed in materials such as KxTiyNi(1−x−y)O and CaCu3Ti4O12. The dielectric measurements carried out on the samples with different thicknesses and electrode materials reflected the influence of extrinsic effects. The impedance studies (100 Hz–10 MHz) in the 180–300 K temperature range revealed the presence of two dielectric relaxations corresponding to the grain boundary and the electrode. The dielectric response of the grain boundary was found to be weakly dependent on the dc bias field (up to 11 V/cm). However, owing to the electrode polarization, the applied ac/dc field had significant effect on the low frequency dielectric response. At low temperatures (100–180 K), the dc conductivity of STMO followed a variable range hopping behavior. Above 180 K, it followed the Arrhenius behavior because of the thermally activated conduction process. The bulk conductivity relaxation owing to the localized hopping of charge carriers obeyed the typical universal dielectric response.

Low-temperature dielectric properties of double-perovskite Ca2CoNbO6

“…The impedance spectrum is extremely advantageous for distinguishing grain and grain boundary contributions [25]. This technique is frequently used to explore and study the dielectric mechanisms of materials with colossal dielectric constants [12,[26][27][28]. We thus perform impedance analysis on CCNO sample in the frequency range from 100 Hz to 10 MHz.…”

“…Several stunning dielectric properties were reported in a number of double perovskites. In spite of the magnetodielectric effect found in La 2 NiMnO 6 [6][7][8] and La 2 CoMnO 6 [9], colossal dielectric constants (dielectric constant larger than 10 3 ) also have been reported [10][11][12]. The results reported by Castro et al.…”

Room temperature electroresistance in Sr2−xGdxMnTiO6 perovskites (0≤x≤1)

“…These insulating grain boundaries also contribute to the large dielectric constant found in these materials [12]. From the technological point of view, it would be important to confirm the intrinsic, not heat-related ER at the room temperature in order to tailor new materials for applications.…”

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

“…The CI spectra were analyzed using an equivalent circuit (EC) model. Empirically, the phenomenological constant phase element (CPE), which is a capacitive element with non-Debye behavior, is used to replace the ideal capacitor with Debye behavior due to the imperfect blocking characteristics of GBs and EIs [12][13][14]. Our EC is composed of a set of parallel ideal resistor (R g ) and ideal capacitor (C g ) circuit (RC-circuit) for grains and a set of parallel ideal resistor (R gb ) and non-ideal CPE circuit (R-CPE) for grain boundaries as schematically shown in the upper right inset of Figure 1(c).…”