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A detailed investigation of structural, electrical and dielectric properties of Pr0.75Bi0.05Sr0.1Ba0.1Mn0.98Ti0.02O3 manganite prepared by the sol-gel method was undertaken. The Rietveld refinement of X-ray diffraction pattern reveals that this compound is indexed in the orthorhombic structure with Pbnm space group. Structural properties are also analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy at room temperature. DC conductivity (σDC) data show the presence of a semiconductor-metal transition at TSM = 360 K. σDC is described by small polaron hopping model at high temperatures and variable range hopping model at low temperatures. AC conductivity results follow the universal Jonsher's power law at relatively low temperatures and Drude's model at high temperatures. The impedance plots display the contribution of both intra- and inter-granular contributions. Dielectric measurements exhibit highly remarkable dielectric permittivities useful in electronic devices. Dielectric losses are shown to be governed by the DC conduction mechanism and described by the Giuntini theory.

In this paper, a new model of thermionic emission current for non-ideal Schottky contacts and a method of extracting electrical parameters are presented. The Au/n-GaAs Schottky structure is fabricated and simulated using Silvaco–Atlas software in a wide temperature range. The proposed method shows series resistance $$ R_{s} $$ values close to those obtained from ln(I)–V method and ideality factor n in good agreement with the reported experimental studies. The barrier height $$ \phi_{b} $$ extracted by our method is in good agreement with those extracted from the band diagram (BD) and capacitance–voltage (C–V) characteristics. It is increased with decreasing temperature, in accordance with the band gap variation with temperature and the reported negative temperature coefficient of the barrier height. Conversely, $$ \phi_{b} $$ obtained from the classical model using ln(I)–V method shows an abnormal behavior and discordance with the $$ \phi_{b} $$ extracted from the band diagram and C–V characteristics. Finally, the proposed model shows identical characteristics with the simulation and the experimental curves, in all temperature range, while the classic model shows large deviations at high bias voltages.

Sn2Sb2S5 materials were synthesized by thermal evaporation using earth-abundant tin, antimony and sulfur elements. The effect of annealing temperature on structural, morphological, optical, thermal and electrical characterization was obtained using many techniques. The deposited films were annealed in air for 1 h at 100 °C and 300 °C. X-ray diffraction analysis reveals that while as-deposited films are amorphous, a crystallized phase, with an orthorhombic crystalline structure, appears after annealing. Via the photothermal deflection spectroscopy, the sub-bandgap energy decreased from 1.98 to 1.75 eV with rising the annealing temperature. Besides, static and dynamic thermal properties of as deposited and annealed Sn2Sb2S5 thin films were measured using electropyroelectric method. It was observed that an increase (40.5–46.5 W m−1 K−1) was found for the thermal conductivity values by increasing annealing temperature, while thermal diffusivity decreases from 12.1 × 10−6 to 9.31 × 10−6 m2 s−1. Moreover, Nyquist spectra performance in the temperature range 300–540 K revealed the presence of a relaxation phenomenon in the microstructure of the studied sample. In addition, the level of the peaks is crashed with temperature, showing that the charge carriers are thermally activated. Finally, Sn2Sb2S5 thin film annealed at 300 °C was found the best sample for use in optoelectronic and solar cell devices. This work suggests a low cost promising compound for scalable synthesis of Sn2Sb2S5 thin films for solar cell and photovoltaic applications.

Bi4-xYbxTi3O12 with x = 0.0, x = 0.1, x = 0.2 and x = 0.3 specimens were synthesized by conventional solid-state reaction. The influence of ytterbium doping on the structural, optical, dielectric and electrical properties of the synthesized compounds were investigated. The X-ray diffraction analysis showed that all samples are homogenous and crystallize in the orthorhombic system with the Fmmm space group. Also, it is found that the unit cell volume (V) goes on decreasing owing to the decrease of lattice parameters (a, b and c) with increasing Yb content. The absorbance measurement reveals that the intensity increases with increasing ytterbium concentrations. Also, it exhibits an additional peak occurred at the wavelength 975 nm. This peak has been attributed to the characteristic transitions from ground state 2F7/2 to excited states 2F5/2 of Yb3+ ions. From DC-resistivity measurements, it is noticed that all compositions exhibit a semiconductor behavior. In addition, it is found that below 420 K, the electrical resistivity was enhanced considerably upon substitution up to x = 0.3. Such behavior was attributed to the decrease of oxygen vacancies density. At 420 K, the parent compound exhibits a saturation region, which shifts to higher temperatures upon rising Yb content. The deduced activation energy values at high temperatures altercated around 990–828 meV. These values are attributed to oxygen vacancies migration. The electrical conductivity behavior of the samples was explained on the basis of jump relaxation model. As well the conductivity spectrum obeys to the Jonscher universal double power law.

In this work, we report the effect of Ti-doping on the structural, electrical and dielectric properties of Pr0.75Bi0.05Sr0.1Ba0.1Mn1−xTixO3 (x = 0 and 0.04) manganites synthesized by sol–gel route. X-ray structural analysis using Rietveld refinement technique reveals that our samples are single phase and crystallize in the orthorhombic system with Pbnm space group. These structures were characterized by impedance spectroscopy in the frequency range from 40 to 1 MHz and temperatures between 80 and 400 K. DC conductivity analysis shows that our samples disclose a semiconductor behaviour with a semiconductor–metal transition temperature TMS at 380 and 360 K for x = 0 and 0.04 respectively. This result shows that the TMS temperature can be controlled by varying the titanium content. AC conductivity (σAC) results show a considerable sensitivity to both temperature and frequency. The impedance plots were well described by an equivalent circuit model taking into account the contributions of semiconductor grains and insulating grain boundaries in the conduction mechanism. Furthermore, a non-Debye type of relaxation in our compounds was confirmed. In addition, we have demonstrated that the dielectric relaxation is hidden by the DC conduction mechanism.

Polycrystalline samples of La0.67-xEuxBa0.33Mn0.85Fe0.15O3 (x = 0.0, 0.1) manganites have been prepared using sol-gel route. Structural characterizations of our materials were performed by powder X-ray diffraction, Scanning Electron Microscopy and by Energy Dispersive X-ray spectroscopy at room temperature. Our samples are single phase and crystallize in the orthorhombic structure with the Pbnm space group. Electrical and dielectric properties of La0.67-xEuxBa0.33Mn0.85Fe0.15O3 (x = 0.0, 0.1) compounds have been studied using impedance spectroscopy technique in the temperature range from 80 to 400 K and the frequency range from 40 to 107 Hz. DC measurements show that the studied structures exhibit semiconductor (SC) behaviour in all temperature range of study. AC data analysis show a transition from SC to metallic behaviour at 160

Barium titanate is one of the most studied perovskite materials owing to its ability to the substitution in both sites, to its high dielectric constant and to its stability. It is characterized by a diversity of remarkable properties, especially ferroelectric and dielectric properties, which can be improved by doping, making this material suitable for many applications. We have investigated the effect of calcium ion substitution on the structural, optical, electrical and dielectric properties of this compound. Ba0.9Ca0.1TiO3 ceramic was elaborated using the solid-state diffusion method. This compound crystallized in the tetragonal phase with a crystallite size of 22 nm. Fourier transform infrared spectroscopy measurements revealed that octahedral vibrations are affected by Ca incorporation. Electrical analyses show that the compound has a semiconductor behavior, and that both grains and grain boundaries are responsible for the thermal evolution of the conduction mechanisms. Two different transition temperatures were detected. One of them coincides with the Curie temperature, which is confirmed by dielectric measurements. The compound shows a high dielectric constant up to 420 K which is seemingly constant in a wide frequency range. Such behavior is sought for the development of energy storage devices.

The impact of Ni doping on the morphological, electrical and dielectric properties in a polycrystalline sample of YMn0.4Fe0.6O3 was investigated. SEM analysis reveals that grain size increases with the rise of Ni concentration in YMn0.4Fe0.6-xNixO3 (x = 0, 0.05, 0.075 and 0.1) nanoparticles up to x = 0.075. The DC conductivity results indicate that all samples exhibit semiconductor behavior over the whole studied temperature range (240–440 K). In addition, the σDC curves show that the conductivity follows the same trend of the grain size with doping. AC conductivity measurements (σAC) are found to obey to Jonscher's universal power law. Actually, the results show that non-overlapping small polaron tunneling (NSPT) is the suitable model that helps to understand the conduction mechanism in our samples. Moreover, the contribution of both grain and grain boundaries in the conduction process is proved by Nyquist spectra which were fitted by an appropriate equivalent circuit. Based on dielectric measurements, it is found that dielectric losses are ruled by the DC conduction process.

Barium titanate is a very attractive perovskite given its ferroelectric, piezoelectric and dielectric properties. These can be further improved by the substitution of barium and titanium by different elements. Introducing both rare earths and/or metals in this compound enhances its optical and electrical properties, thus making it a multifunctional material suitable for many different applications. In the present work, the compound Ba0·91Er0·1/3Ca0·04Ti0·92Sn0·08O3 is prepared by solid state reaction and its structural, morphological, thermal optical and electrical properties are investigated in detail by X ray diffraction, scanning electron microscopy, differential scanning calorimetric, absorption spectroscopy and impedance spectroscopy respectively. Scanning electron microscopy shows that the material is composed by a major polycrystalline phase with micrometric grain size. Two-phase transitions at 448 K and 572 K are deduced from thermal and electrical measurements. The optical measurements indicate that both erbium and tin are well introduced in the structure, which is confirmed by energy dispersive spectroscopy, and affects the vibrational modes. a. c. and d. c. electrical measurements show that, depending on the measurement temperature range, conduction mechanism is either a non-overlapping small polaron tunneling or a correlated barrier hopping model. . Moreover, dielectric measurements prove a high dielectric constant and identify a phase transition from the ferroelectric phase to paraelectric one which is in agreement with literature. Such substitution improves the compound properties and makes it suitable for different devices.

Polycrystalline ytterbium modified bismuth titanate Bi4-xYbxTi3O12 (x = 0, 0.1, 0.2, and 0.3) solid solutions have been synthesized using a solid state reaction method. The effect of varying the ytterbium content on the structural, morphological, vibrational, and impedance properties of this ceramic have been investigated. According to the experimental results obtained from scanning electron microscopy combined with energy dispersive X-ray analysis, a highly dense grain structure and a randomly oriented plate-like morphology were observed, showing an increase in the material grain size with Yb content. Besides, all the samples were found to be free from any other secondary phase. By means of Raman spectroscopy, it was observed that (Bi2O2)2+ layers remain unaffected with composition variation. These observations prove that Yb3+ substitution for Bi3+ occur predominantly, not only in pseudo-perovskite (Bi2Ti3O12)2- sites, but also in (Bi2O2)2+ layers, leading to cationic disorder and to a decrease in the TiO6 octahedral distortion. Raman measurements show also that all compounds exhibit a perovskite-type orthorhombic structure. This latter result is consistent with Fourier transform infra red analysis, which shows the appearance of two absorption bands below 830 cm−1. The optical band gap obtained from UV–visible spectroscopy has been found to slightly decrease from 3.1 to 3.04 eV with increasing Yb3+ substitution from x = 0 to x = 0.3, respectively. The thermal stability was also investigated. It was found from the differential scanning calorimetry that the Curie temperature (Tc) shifted backwards with increasing Yb content. No significant weight loss was found in the thermo-gravimetric analysis curve up to 800 °C temperature. Besides, the impedance spectroscopy studies show a non-Debye-type relaxation and a relaxation frequency shift to higher side with the increase in temperature. The Nyquist plot shows overlapping semicircles which indicate the existence of both grain and grain boundary effect in the prepared ceramic.