Influence of stoichiometry on the dielectric and ferroelectric properties of the tunable (Ba,Sr)TiO3 ceramics investigated by First Order Reversal Curves method

Hysteresis and tunability characteristics of Ba(Zr,Ti)O3 ceramics described by First Order Reversal Curves diagrams

“…Since there is not a net separation between the reversible (along the bias axis E c = 0) and the irreversible (for E c = 0) components of the polarization on the FORC distribution as in other ferroelectrics, 12,16 it results that a continuous distribution of energy barriers from zero to non-zero values is characteristic to these BZT ceramics. A similar behavior was found for some BST compositions 13 and is related to the high degree of local compositional inhomogeneity of the solid solutions, giving rise to broad distributed Curie temperatures and coercivities. Therefore, the sample BZT2 is much homogeneous from the switching point of view, i.e.…”

“…The field-induced polarization P(E) is accompanied by hysteresis and involves reversible/irreversible domain dynamics. Apart the classical methods of investigating, the more recent one based on the First Order Reversal Curves (FORC), 12,13 related to the Preisach model in ferroics, 14,15 proved its sensitivity to the crystallite orientation, imprint effects in films 12,13 and anisotropic porosity in ceramics, 16 giving also information on the field-dependence of the differential susceptibility. 16 This approach is used here to describe the switching and ac-tunability characteristics in BaTi 1−x Zr x TiO 3 ceramics with two grain sizes: 0.75 and 3.3 m.…”

Frequency-temperature dependent dynamics of dielectrics in ferric oxoborate Fe3BO6 of cocktail structure of nanorods

“…As compared in Table 1, it stands reasonably larger in comparison to most of well-known high-" r dielectrics [23][24][25][26][27][28][29]. Such high " r -value can be explained in presence of electrical conductivity of the sample when it designs a model resistor-capacitor network in terms of a bonded v-B 2 O 3 surface layer (insulator) on the individual Fe 3 BO 6 crystallites (a rather conductor).…”

“…Phonons (or magnons) in a lattice Fe 3 BO 6 set-up an electroelastic (or magnetoelastic) interaction with the charge carriers if couple at elevated frequencies of the applied electric field [17,33]. As in model magnetoelectric materials [26,27], thermal induced relaxations of (i) electric dipoles in localized space charges and (ii) magnetic dipoles in valence electrons (3d 5 -Fe 3þ in Fe 3 BO 6 ) can exchange couple so that a stable " r -value is observed over extended frequencies. Fe 3þ magnons in a similar example Sr 0.97 Ti 1Àx Fe x O 3 (x 0.1) [25] is known to stifle " r -value, dielectric relaxations, variable-range-hopping conduction, but adversely favor ac conductivity with temperature in a sublinear power-law.…”

“…No such wide temperature range of a steady power-loss is feasible in titanates or niobates of wellknown ferroelectrics. Phase transitions in thermally activated dielectric parameters in T C point and/or oxygen vacancies disrupt signal at early temperatures [25][26][27][28]40]. An intense peak shoots-up at T C .…”