RESUMEN
The cobalt and titanium modified BiFeO3 [i.e., Bi(Co0.40Ti0.40Fe0.20)O3; referred to as BCTF80/20] solid solution was synthesized via a simple and cost effective solid-state technique, and numerous sets of studies (structural, elemental, electrical, leakage current, multiferroic and other properties) were carried out and reported. The basic structural symmetry was investigated and phase identification of the prepared samples was carried out by analyzing powder X-ray diffraction data through the widely used "POWDMULT" software. From the XRD pattern [Fig. 2(a) of RSC Adv., 2018, 8, 36939], it is clear that almost all the reflection peaks (including those that appear to be split) have been indexed to a single phase (based on the best agreement between experimental and calculated interplanar distances and minimum standard deviation) system using the above software. The lattice parameters, average crystallite size, cell volume, and micro-strain value are strongly affected by the addition of Co and Ti into the bismuth ferrite. The significant enhancement of various parameter (i.e., electrical, multiferroic and so on) values of BCTF80/20 ceramics may make them promising candidates for the development of new generation electronic devices.
RESUMEN
This paper presents the fabrication of a polycrystalline sample of the above electronic system by a mixed-oxide technique. The X-ray diffraction pattern show the evolution of perovskite phase (including some impurity phase). The rhombohedral symmetry and crystallite size of 42 nm were also found from the XRD. The distribution of grains in the microstructure suggests the formation of high density ceramics. The role of grains, grain boundaries and interface on resistive (impedance, electrical modulus and electrical transport) and insulating (dielectric) has been investigated over a wide range of frequencies (103-106 Hz) and temperatures (25-400 °C) using spectroscopy (dielectric, modulus and impedance) techniques. The Nyquist plot illustrates the presence of effects such as grain and grain boundary over selected temperatures. Analysis of conductivity spectra reveals that the electrical transport process of the material is influenced by charge transfer by hopping. The complex modulus spectrum also describes the dielectric relaxation of the material. The study of field dependent polarization reveals the existence of ferroelectricity in the material.
RESUMEN
A solid solution of bismuth cobalt titanate [Bi(Co0.5Ti0.5)O3] and bismuth ferrite (BiFeO3) with a composition Bi(Co0.40Ti0.40Fe0.20)O3 (abbreviated as BCTF80/20) was synthesized via a cost effective solid-state technique. Phase identification and basic structural symmetry of the samples were determined by analyzing powder X-ray diffraction data. Field emission scanning electron micrograph (FE-SEM) and energy dispersive X-ray (EDX) spectra were analyzed to evaluate the micro-structural aspects (shape and size, distribution of grains) as well as a quantitative evaluation of the sample. The average crystallite (particle) and grain size were found to be â¼30 nm and â¼1-2 micron, respectively. The electrical parameters (dielectric constant, tangent loss, impedance, modulus, and conductivity) of as-synthesized material were obtained in a temperature range of 300 to 773 K and frequency range of 1 kHz and 1000 kHz. The strong correlation of microstructure (i.e., grains, grain boundary, etc.) and electrical parameters of this material were observed. The frequency dependence of electrical impedance and modulus exhibited a deviation from an ideal Debye-like relaxation process. The dependence of dielectric relaxation mechanism on frequency and temperature is discussed in detail. The field dependent polarization (P-E hysteresis loop) of BCTF80/20 exhibited an enhanced value of remnant polarization as compared to that of BiFeO3 (referred as BFO). At room temperature (300 K), the magnetic hysteresis loop measurements also showed a significant improvement in the magnetization of BCTF80/20. Thus, based on these enhanced values of remnant polarization and magnetic parameters, we can assume that BCTF80/20 may be considered as a promising candidate for some new generations of electronic devices.
RESUMEN
A Pb(Fe(½)Nb(½))O(3) ceramic sample was prepared through a high temperature solid-state reaction technique. The formation of a single-phase perovskite compound was confirmed by an x-ray diffraction technique. Dielectric and impedance parameters were measured as a function of frequency (10(2)-10(6) Hz) at different temperatures (28-200 °C). The results were described using an equivalent circuit model and by extending the universal capacitor concept introduced by Jonscher. Bulk permittivity of the material and the power law exponent (extracted from impedance data) exhibits an anomaly at a particular temperature related to the ferroelectric-paraelectric transition. A slow relaxation process has been observed in the vicinity of the transition temperature. Temperature dependent magnetization (2-300 K) was measured at different magnetic fields in both zero-field-cooled (ZFC) and field-cooled (FC) modes. An antiferromagnetic transition was observed at 158 K but an unusual increase in magnetization below this transition indicates the onset of weak ferromagnetism at low temperature in this system. Nonlinear M-H and a finite opening in the hysteresis loop at 2 K substantiate the presence of ferromagnetic interactions. Significantly, a thermomagnetic history-dependent feature is observed below 9 K. The ZFC magnetization shows a sharp fall and it bifurcates from the monotonically increasing FC counterpart on decreasing temperature. This temperature, where ZFC magnetization shows a sharp peak, decreases with the increase in measurement field and it indicates the presence of a metastable magnetic state at low temperature.
RESUMEN
Nanocrystalline ferroelectric Pb0.92Sm0.08(Zr0.53Ti0.47)0.98O3 with high dielectric constant has been synthesized by mechanical alloying (high energy ball milling). The ferroelectric material exhibits novel behavior when its crystallite size falls below a critical length scale of 40 nm. We observed phenomena such as significant decrease in dielectric constant and phase transition from Tetragonal to Cubic structure on reduction in crystallite size below 40 nm.