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The polycrystalline sample of BiFe1−xNbxO3 (BFNO) (where x = 0.00, 0.10, and 0.20) (BFO, BFNO-1, and BFNO-2) bulk ceramics has been synthesized by cost-effective high-temperature solid-state reaction technique. Structural properties of the prepared samples were investigated through X-ray diffraction (XRD) techniques. The preliminary structural analysis of the samples confirmed that the structures of Nb-doped BiFeO3 samples are rhombohedral with space group R3c. The UV–Vis-spectroscopy analysis reveals that the absorbance value decreases with the increase in concentration, and the calculated optical band gap value lies between 2.3 and 3.47 eV. The frequency response of the ceramic materials has been reported within the range of (1 kHz–1 MHz) with the variation of temperature (30–500 °C). The impedance analysis exhibits the presence of grain and grain boundary effects, and the existence of NTCR behaviour in the materials. The frequency dependence of ac conductivity of the material follows Jonscher’s universal power law, confirmation of the analysis’s reliability, and sample’s high quality. [ABSTRACT FROM AUTHOR]

In this communication, the cerium (Ce) modified (Bi0.4Fe0.4)(Pb0.6Ti0.3Ce0.3)O3 (BF-PT) ceramics is prepared by conventional solid-state reaction technique. The compound is found to crystallize in the rhombohedral crystal system with space group R-3c (#167). The refined lattice parameters are a = b = 4.989 Å, c = 17.062 Å, α = β = 90 ∘ , γ = 120 ∘ , V = 367.78 Å3 and ρ = 2.71 g/cm3 (JCPDS No.-00-005-0586). The average crystallite size and lattice micro-strain in the ceramics are estimated at 47.6 nm and 0.117% respectively. Scanning electron microscopy analysis indicates low porosity and well-defined grain boundaries, with an average grain size of 13.7 μm. Raman spectroscopy confirms the presence of all constituent elements and ferroelectric character. Ultraviolet–visible (UV–Vis) spectroscopy analysis suggests a bandgap of 1.72 eV for the modified BF-BT ceramics, which is suitable for photovoltaic applications. The study of complex impedance suggests a Cole–Cole-type relaxation with a decrease in bulk resistance from 6.283 × 1013 Ω cm2 at 25°C to 1.783 × 104 Ω cm2 at 500°C, confirming the negative temperature coefficient of resistance. The calculated activation energies are 849.8 meV, 706.5 meV, 575.1 meV, and 499.4 meV at 1 kHz, 10 kHz, 100 kHz, and 1000 kHz, indicating ionization of oxygen vacancy and the involvement of the released electrons in the hopping conduction process, and support a thermally activated conduction mechanism. The increase in the peak frequency difference between the Z ″ and M ″ spectrum with temperature suggesting a non-Debye-type relaxation in the material. The material is characterized to a high dielectric constant and low tangent loss suitable for optoelectronic devices. [ABSTRACT FROM AUTHOR]

A correction is presented to the article "Efect of Cerium on Structural and Dielectric Properties of Modifed BiFeO3‑PbTiO3 Ceramics for Photovoltaic Applications."

This article reports the development and characterizations (structural, surface topographical, fractal, dielectric, transport, impedance, resistive, and current-voltage properties) of a defect brownmillerite material KBiFeMnO 5 . Preliminary investigation of the X-ray diffraction (XRD) pattern with the Monte Carlo technique with McMaille 4.0 shows monoclinic symmetry having lattice parameters: a = 8.261 Å, b = 8.251 Å, c = 7.524 Å, and β = 108.58°. The analysis of the Williamson-Hall plot illustrates the average crystallite size and micro-lattice strain are 124.6 nm and 0.002, respectively. The scanning electron microscopic image examines the microstructural surface topography, fractal analysis, and surface roughness (using the standard of ISO25178) of the material. Maxwell-Wagner dielectric dispersion, relaxation, and transport mechanisms are investigated utilizing dielectric, impedance, and conductivity spectra accumulated within the experimental frequency (1 kHz to 1 MHz) and temperature (25-500 °C) ranges. The energy band of an intrinsic region with a 1 MHz frequency indicates the semiconducting behavior of the material. The logarithmic current density and electric field are used to investigate the presence of ohmic and space charge limited conduction (SCLC) mechanisms. The thermistor constant ( β ) is determined to be 4633.86, and the temperature coefficient of resistance (TCR) is -0.00322, which may be suitable for high-temperature NTC thermistors and other related device applications., Competing Interests: The authors confirm that the research presented in this work has not been influenced by any known financial conflicts of interest or close personal ties. In addition to the above, we have no conflicts of interest with anybody except Paweł E. Tomaszewski., (This journal is © The Royal Society of Chemistry.)

The cobalt and titanium modified BiFeO 3 [ i.e. , Bi(Co 0.40 Ti 0.40 Fe 0.20 )O 3 ; 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., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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 (10 3 -10 6 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.

A solid solution of bismuth cobalt titanate [Bi(Co 0.5 Ti 0.5 )O 3 ] and bismuth ferrite (BiFeO 3 ) with a composition Bi(Co 0.40 Ti 0.40 Fe 0.20 )O 3 (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 ∼30 nm and ∼1-2 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 BiFeO 3 (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., Competing Interests: The authors declare that they have no conflicts of interest., (This journal is © The Royal Society of Chemistry.)