Investigation on structural, dielectric and ferroelectric properties of samarium-substituted BiFeO₃–PbTiO₃ composites

Abstract

The polycrystalline samples of 0.8BiSm x Fe 1Àx O 3 -0.2PbTiO 3 (x ¼ 0:05; 0:10; 0:15 and 0.20) were prepared by using the conventional solid-state reaction technique and sintered at high temperature (850 C). X-ray diffraction (XRD) confirms the distorted rhombohedral crystal structure for all the composites at room temperature. The surface morphology was checked by field-emission scanning electron microscope (FESEM) technique and homogeneous mixing of the components was confirmed by energydispersive analysis of X-ray (EDAX). The detailed study of dielectric properties of the composites reveals an increasing nature of dielectric constant (" r ) and loss tangent (tan) with the increase of temperature due to thermal activation. The Arrhenius plots of temperature dependence of AC conductivity yield the activation energy within the material at high-temperature range. The ferroelectric study shows that the remnant polarization decreases with the increase of Samarium (Sm) concentration.

Effect of Nd3+ substitution on structural, ferroelectric, magnetic and electrical properties of BiFeO3–PbTiO3 binary system

“…Recently, Sahu et al have reported enhanced resistivity and relaxor dielectric behavior above room temperature in Gd 3+ modified 0.8BF-0.2PT ceramic samples [31]. The same group also reported the enhancement in dielectric behavior with increase in Sm 3+ doping in 0.8BF-0.2PT solid solutions [32].…”

Complex Dielectric and Impedance Spectroscopic Studies in a Multiferroic Composite of Bi2Fe4O9-BiFeO3

“…A thin film of BiFeO 3 has been demonstrated to show very large polarization [1], but it is deduced that the grain boundaries in a polycrystalline film and defect structures could result in degradation of ferroelectric polarization effects and leakage characteristics. Thus, the need for studies of multiphase or composite oxides based on bismuth iron oxides exhibiting multiferroic properties is very important [4][5][6][7]. To be considered as important, the composite material concerned should exhibit strong coupling effects, for example, between ferroelectric and antiferromagnetic properties [8,9].…”

Effect of Sr-substitution on the structural and dielectric properties of LaFeO3 perovskite materials

“…The high frequency semicircle is the grain contribution and the grain boundary contribution comes from the low frequency semicircle. 7,17 The grain conductivity and grain boundary contribution can be calculated 10 with the following equations: where g and gb are conductivity contributed by grain and grain boundary, t is thickness of the samples, A is surface area of the samples, and R g and R gb are resistivity contributed by grain and grain boundary. Table 2 shows the grain and grain boundary conductivity obtained from the equivalent electrical circuit model of the La 1Àx Sr x FeO 3 samples.…”

“…Based on the values obtained for dc at all temperatures (T), the conduction activation energy can be calculated using the Arrhenius relation. 8,17 Figure 8 shows the linear relation between 1000/T and ln dc . The conduction activation energy decreased with increasing Sr-substitution.…”