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Biopolymers obtained from renewable resources became the center of public interest by virtue of their environmental and commercial advantages. Natural polymers such as starch, almond gum, chitosan and arabic gum were investigated to get fully or partially biodegradable dielectric material. Thus, in this article we study the material properties of cashew gum. This biopolymer is an exudate collected from occidental anacardium tree. For this investigation, scanning electron microscopy of powder and thin film cashew gum showed homogenous and slightly rough surface morphology with visible wrinkles. The thermal analyses such as thermogravimetric (TGA) and differential scanning calorimeter were realized. thermogravimetric thermogram shows two distinct stages of decomposition. The first around 150°C is attributed to moisture evaporation with loss in weight of 9.7%. The second transition, between 255°C and 330°C, is related to the decomposition of cashew gum with loss in weight of 50%. UV-visible spectra of the cashew gum thin film show a low absorbance and high transmittance. For this material, we obtained a direct optical band gap around 4.56 eV. In addition, the dielectric and electrical characterizations lead to conclude that cashew gum may be interesting for transistor applications as a gate dielectric.

Ferrite compounds have recently attracted significant interest because of their multifunctional properties.

Nature provides a wide range of dielectric biopolymers that can be used in electronic devices. In this work, organic field-effect transistors (OFETs) using khaya gum (KG), a natural, biodegradable biopolymer that can be directly collected from khaya senegalensis trees, as the gate dielectric are demonstrated. The fabricated bottom gate/top contact poly (3,6-di (2-thien-5-yl)-2,5-di (2-octyldodecyl)-pyrrolo [3,4-c] pyrrole-1,4-dione) thieno [3,2-b] thiophene) (DPPTTT) –(polymethylmethacrylate) (PMMA) OFETs operate at 3 V with a saturation field-effect mobility (μsat) 0.3 cm2V−1 s−1, threshold voltage (Vth) -1.3 V, subthreshold swing (SS) 450 mV/dec, and current on/off ratios (ION/OFF) larger than 3 × 103. Significantly, the gate leakage current (IG) does not exceed 10–8 A for the gate-source voltage (VGS) ≤-3 V. UV–Vis spectra analysis shows that the prepared khaya gum films exhibit low absorbance and high transparency (up to 90%) with a calculated optical band gap of about 4.3 eV. Thermal characterization shows two stages of decomposition and a glass transition at around 60 °C. Characterization of metal–insulator-metal (MIM) capacitors using khaya gum reveals that the KG-based MIM capacitors possess a relatively high capacitance per unit area (Ci) of 130 ± 3 nF/cm2 at 1 kHz. As a result, khaya gum emerges as the dielectric of choice for low voltage, transparent OFETs where environmentally friendly device manufacturing is required.

The development of multifunctional materials is an exceptional research area, which is aimed at enhancing the versatility of materials in various applications. In this context, the exceptional properties of ferrite materials have attracted the attention of researchers. For this reason, we synthesized LiMn

Natural substances are potential compounds for green electronic devices. So, scientists have to explore and optimize their properties to insert them as active layers in electronic heterostructures. In this study, microstructural, optical, and electrical properties of thin layers of the propolis are investigated. Propolis is a biological organic bioactive material produced by honeybees. A stable, bioactive, green, and low-cost thin layer of this biocompatible material was deposited on different substrates using a propolis alcohol solution. The morphological studies show that the propolis thin film is dense and well covers the substrate surfaces. Transmittance spectra show that propolis film cuts off blue and ultraviolet (UV) radiation, which are responsible for food oxidation, nutrient losses, flavor degradation, and discoloration. Therefore, to prevent food deterioration, a propolis film can be used in food packaging. For red and near-infrared radiation (∼600-2700 nm), a propolis film is transparent. Between near-infrared and mid-infrared radiation (∼2700-3200 nm), a propolis film reveals significant photosensitivity and so can be used as a photosensor. The propolis film reveals an energy gap of 2.88 eV at room temperature, which enables potential optoelectronic applications in the UV and blue ranges. The electrical study shows that the propolis layer has semiconductor behavior and can be a potential active layer in biocompatible temperature sensors. In addition to its medical, pharmaceutical, and food industry applications, in light of this study, propolis presents amazing optical and electrical properties and is a promising candidate for food packaging, optoelectronics, transparent electronics, and bioelectronics.

The CsYP2O7 compound was synthesized by the classical "solid-state" reaction. The phase identification of the obtained samples was performed by X-ray diffraction proving their crystallization in the monoclinic structure with the P21/c space group. Its morphology and the particle size were evaluated by scanning electron microscope (SEM). The impedance spectroscopy technique was used in order to understand the evolution of the electrical behavior and the relaxation process in this material. Accordingly, the experimental data of the Nyquist were fitted to the equivalent circuit created by a series combination of two cells. As a matter of fact, the DC conductivity exhibits a semiconductor behavior. The AC conductivity obeys the Jonscher's law. The close values, of activation energies, obtained from the dc-conductivity and hopping frequencies, prove that the transport of the charge carrier happens through an ion hopping mechanism, influenced by the motion of the Cs+ cations within the structure of CsYP2O7. The electrical modulus confirms the existence of non-Debye type relaxation behavior. The optical properties of UV–visible spectroscopy for our sample showed that the gap value is equal to 3.7 eV.

La0.4Pr0.25Ca0.35-xAgxMnO3 samples were elaborated using sol–gel method. X-ray diffraction study indicates that the investigated compounds exhibit an orthorhombic structure with Pbnm space-group sy...

The present paper provides significant results about the impact of iron doping on the ZnO nanoparticles’ structural and electrical properties. Fe-doped ZnO (ZnO:Fe) nanoparticles with varying doping concentrations from 0 to 5% were effectively synthesized by a simple co-precipitation method. The X-ray diffraction (XRD) studies revealed that all compositions crystallize in the hexagonal wurtzite structure with the P63mc space group. They also proved the presence of a secondary phase accredited to ZnFe2O4 for ZnO:Fe 5% sample. Concerning the transmission electron microscopy, it demonstrated that the formed nanoparticles are spherical. The electrical properties were explored by complex impedance spectroscopy in the 40–107 Hz frequency range and 400–500 K temperature domains. The comparative Nyquist plots at fixed temperature 440 K suggested that the impedance value dropped with the augmentation of Fe doping concentration. Furthermore, the electrical conductivity and dielectric properties were explored as a function of frequency and temperature in the same range. The obtained results demonstrated that iron doping enhanced the AC conductivity at the same selected temperature 440 K. The analysis of the AC conductivity frequency dependence of the ZnO:Fe 1% sample was carried out by Jonscher’s universal power law and the conduction mechanism was interpreted by the overlapping-large polaron tunneling (OLPT) model. Both impedance and modulus analyses were found to display the contribution of grain and grain boundary to the electrical response of the ZnO:Fe 1% sample. Moreover, the dielectric characterization had affirmed that both dielectric constant and dielectric loss decrease with the increase in frequency and increase with the increase in temperature. These two parameters were found to augment with Fe doping. The observed properties had proven that Fe doped ZnO nanoparticles was very functional for the electric storage applications.

The cobaltite spinel MnCo2O4 nanopowder was prepared by the sol–gel method. X-ray diffraction shows the pure compound that crystallized in the cubic structure with the Fd $$\stackrel{-}{3}$$ m space group. The infrared spectrum (IR) revealed two absorption peaks that can be attributed to Mn–O and Co–O vibrations in the octahedral and tetrahedral sites, respectively. The electrical and dielectric studies were characterized by impedance spectroscopy (IS) at different frequencies (40–106Hz) and temperatures (200–440K). As a matter of fact, the DC conductivity exhibits a semiconductor behavior. It is worth mentioning that the conductivity of our investigated cobaltite spinel was found to be σ = 6.10−3 Sm−1 at room temperature. These results allowed this material to be a good candidate for potential application as an anode material (fuel cell). The AC conductivity obeys the Jonscher's law at low temperatures T 340K. Moreover, the dielectric result shows the permittivity (e '≈ 103) which is due to the contribution of the Maxwell–Wagner polarization.

International audience; The alkylammonium halogenoferrate families are subjected to diverse studies according to their wide field application. However, these compounds show various transitions depending on the preparation process. In this paper, the [(C2H5)4N]FeCl4 compound was successfully synthesized using a slow evaporation solution growth method at room temperature. An optical absorption measurement confirms the semiconductor nature with a band gap around 2.95 eV. The X-ray powder diffraction (XRPD) data confirmed the formation of a single-phase with hexagonal-type structure. The differential scanning calorimetry (DSC) indicated that the [(C2H5)4N]FeCl4 compound undergoes eight reversible phase transitions between 193 and 443 K. At high temperature (T > 423 K) the plastic nature of the crystals was confirmed. Temperature-controlled X-ray diffraction reveals that the thermal expansion of the crystal structure is non homothetic in the (a,b) plane and along the c axis. The temperature dependence of the Raman spectra up to 443 K revealed specific reorientations and molecular displacements of the organic and inorganic components associated with the phase transitions. We aim to thermally stabilize the [(C2H5)4N]FeCl4 compound which has a band gap suitable for photocatalytic processes.

LiFe5O8 (Li0.5Fe2.5O4) nanopowders were synthesized by the sol-gel auto-combustion method and were annealed at different temperatures of 500, 600, 700, and 1100 °C. The spinel phase formation of these samples has been confirmed by X-ray powder diffraction (XRD) technique and Fourier transform infrared (FTIR) spectroscopy. XRD analysis revealed order to disorder phase transition of Li0.5Fe2.5O4 during the annealing temperature. This structural transition was also confirmed by differential scanning calorimetry (DSC). The scanning electronic microscopy images reveal that nanoparticles size increases from 9 nm to 500 nm with increasing annealing temperature. The influence of particle size on elastic parameters has been investigated by FTIR spectroscopy. The band gap energy estimated by UV–vis spectroscopy of LiFe5O8 nanoparticles decreased from 1.41 to 1.27 eV when the annealing temperature increases. Furthermore, impedance spectroscopy measurements have been carried out over large frequency and temperature ranges. The conductivity spectrum indicates that the tested specimens are defective. It also shows that the conductivity runs to frequency according to Jonscher’s law. Static conductivity responds to temperature in conformity with a small polaron hopping model whereas dispersive one evaluates according to correlated hopping model. The conductivity gets mixed (electronic and ionic) only when samples were annealed at 700 °C and 1100 °C. According to the Nyquist diagram, each sample is capacitive and resistive. Increasing annealing temperature led to major improvements in permittivity, and a giant low-frequency dielectric constant was observed in the sample annealed at 1100 °C. The total loss (ɛ″) is governed by the conduction mechanism and described by Giuntini's theory. The improved electrical, optical, and elastic properties indicates the potential application LiFe5O8 nanoparticles in future multifunctional devices (microelectro-mechanical systems (MEMS), optoelectronic and photovoltaic, photocatalytic activity under visible light, bolometer, low temperature co-fired ceramics (LTCC) and gas sensor applications.).

Morphological, electrical and dielectric properties of manganese-doped lanthanide orthoferrites La0.6Ga0.4Fe1-xMnxO3 (x = 0; 0.1; 0.2 and 0.3) are investigated. Scanning electron microscopy charact...

The orthorhombic Pr0.7Ca0.3Mn0.95Fe0.05O3 manganite is subject to magnetic and impedance spectroscopy measurements. This sample shows a paramagnetic to ferromagnetic phase transition at about 90 K. According to the Banerjee criterion, the nature of the magnetic transition is found to be of second order.The conductance spectra for Pr0.7Ca0.3Mn0.95Fe0.05O3 ceramic obey the power law variation for characterizing the hopping dynamics of charge carriers. The activation energies extracted from the dc conductance and hopping frequency show a positive correlation. Using the scaling approach, the conductance spectra are merged into a single master curve, confirming the validity of the time–temperature superposition principle. Equally, a strong deviation from the Summerfield scaling is observed. The random barrier model (RBM) is applied to correct this anomaly and a single master curve is constructed with a positive value of the scaling parameter α. Such parameter indicates a coulomb exchange between the interacting particles. Impedance results confirm the contribution of the resistive grain boundary on the electrical properties and the appearance of multiple electrical relaxation phenomena in Pr0.7Ca0.3Mn0.95Fe0.05O3 sample. From the evolution of the derivative ANC with temperature, we confirm the presence of various conduction mechanisms. The Nyquist plots show that the increase in temperature is followed by a decrease in the grain resistance (Rg) and the grain boundary resistance (Rgb) values. Such monotonic decrease confirms a predominant role of grain boundary contribution in governing the transport properties of Pr0.7Ca0.3Mn0.95Fe0.05O3 compound.

Conductivity spectra of La0.5Ca0.3Ag0.2MnO3 (LCAM) oxide have been investigated in the temperature range [80 K–680 K]. The studied system displays a semiconductor behavior over the explored temperature and frequency ranges. From direct current study, the transport of charge carries is assisted via disorder energy below θD/4. For the temperature range [θD/4- θD/2], the transport properties are governed by activation of Mott-variable range hopping (Mott-VRH) process. Beyond θD/2, the conduction phenomena are assisted through the thermally activation of the small polaron hopping (SPH) mechanism. At high frequencies, the conductivity spectra reveal a dispersive region. They are explained by the double Jonscher response. The latter side was characterized by the appearance of the overlapping-large-polaron-tunneling (OLPT), the correlated barrier hopping (CBH) and the non small polaron tunneling (NSPT) conduction processes. It is found that the calculated disorder energy is frequency independent. At elevated frequencies, the hopping energy is predicted to decrease with increasing frequency which can be related to the change in the Polarons radius. In the temperature range [80 K–220 K], the conductivity spectra follow double Jonscher law. Using the scaling model, the spectra merge into a single master curve, which confirmed the validity of the time temperature superposition principle (TTSP). A confident divergence from the Summerfield is noticed at high frequencies. It proves that the charge mobility is temperature dependant. The Summerfield correction scaling is effectuated by introducing a scaling positive parameter (α = 1.2). An excellent coalescence of conductivity spectra is observed.

In the present investigation, La0.75Ba0.10Sr0.15FeO2.875-δ oxygen-deficient ferrites with δ = 0.00, 0.125 and 0.25 were synthesized by sol–gel method. The physical characterization has been carried out by X-ray diffraction, scanning electron microscope SEM, Raman spectroscopy, and complex impedance. All samples are formed in orthorhombic crystal symmetry with Pnma space group. Synthesized compounds have nanocrystallite size of 32–46 nm. Raman spectrum shows the oxygen vacancy effect on the tilt and stretching phonon modes. Electric properties were investigated in the framework of impedance and electric conductivity. The complex impedance was measured over a wide range of temperatures (300–380 K) and frequencies (40 Hz–1 MHz). The electrical measurements indicate semiconductor behavior for the three compositions and emphasize the evidence of contribution of grain boundaries in the transport properties. The ac conductivity curves obey the Jonsher universal power law and are assigned to hopping conduction mechanism. It is found that the values of activation energy, estimated from the conductivity analysis, are in the same order with those deduced from relaxation process. Such result proves that both processes, conduction and relaxation, are related to the same defect.

Characterization of the electrical properties of Pr0.65Ca0.25Pb0.1MnO3 ceramic, prepared by the solid-state method, is conducted using the impedance spectroscopy technique. Ac-conductivity measurements reveal the presence of two electrical behaviors. A semiconductor character obtained at low-temperature ranges of 80–160 K, and a metallic behavior found at high-temperature ranges of 180–400 K. The temperature dependence of the exponent s confirms the contribution of two conduction processes in the transport mechanism. In the range of T 140 K, the conduction process is governed by the correlated barrier hopping (CBH) model. Finally, beyond T = 250 K, the dc-conductivity is characterized by the appearance of a saturation region.

La0.7Ga0.3Fel-xTixO3 (x = 0, 0.1, 0.2, and 0.3) polycrystalline compounds were successfully prepared using the solid–solid process. The structural study proves that the samples are centrosymmetric ...

In this work, we report the synthesis of undoped ZnO and In-doped ZnO nanoparticles by sol–gel method from 0 to 5 wt% of In amount. The effect of indium incorporation on structural and electrical properties of these samples was investigated. X-ray diffraction analysis confirms the formation of undoped ZnO and In-doped ZnO nanopowders with a hexagonal wurtzite crystalline structure and the average crystallite size varies between 31 and 55 nm. The morphological study shows that the shape of the crystallites is hexagonal and it changes into cylindrical prismatic after doping. Further, the study of electrical response was carried out by impedance spectroscopy. The electrical properties of these samples are dependent on temperature and frequency. We find that the conductivity increases with increasing In dopant. It has been found that the highest conductivity corresponds to the concentration 3% of indium content. Concerning the complex impedance analysis, the equivalent circuit of grain consists of resistance and constant phase element in parallel. These results contribute to various technological applications.

In this work, the ceramic Fe-PrCaMnO manganite was synthesized by means of standard high-temperature solid-state reaction technique. X-ray diffraction of Pr0.7Ca0·3Mn0·95Fe0·05O3 was indexed to a perovskite single phase. Then, all reflections appearing in the diffraction patterns were indexed and assigned to the orthorhombic Pnma space group. Electrical investigations show that the sample presents two dissimilar behaviours. A semiconductor character was observed at low temperature region [80K–250K]. Then, a metallic behaviour was detected beyond T = 250K. Then, a saturation region was marked. At low temperature region, ac-conductivity analysis shows the coexistence of two frequency dependent conduction mechanisms. The Correlated Barrier Hopping (CBH) mechanism was observed at the intermediate frequency range and a Non-Small Polaron Tunneling (NSPT) one was detected at high frequency side. In the temperature range [140K–170K], a signature of a Quantum Mechanical Tunneling (QMT) conduction mechanism was noticed. Then, beyond T = 170 K, the CBH mechanism dominated the transport properties. A double Jonscher response and the contribution of multiple mechanisms in electrical conductivity processes of Fe-PrCaMnO system were confirmed. Then, the frequency dependence of ac-conductance has been clarified by several conduction Models (CBH, NSPT and QMT).

In this paper, two Schottky structures of Au/n-GaAs (sample A) and Au/0.8 nm-GaN/n-GaAs (sample B) were fabricated and electrically characterized by current–voltage measurements at different temperatures. Two models, a classical one and another previously proposed named Helal model ref (Helal et al. Eur Phys J Plus, 135:1–14, 2020). Both the models show that the ideality factor n grows as the temperature decreases, and the second model shows higher values especially at low temperatures. The barrier height $$\Phi_{b}$$ Φ b calculated using the second model decreases when temperature increases for both structures, according to the temperature-dependent band gap, and in contrast to the results obtained by the classical model. Moreover, the second model gives a homogeneous Schottky barrier height and the best resolution of Richardson constant $$A^{*}$$ A ∗ , for both structures. On the other hand, the classical model shows an inhomogeneity of the barrier height and very far values of $$A^{*}$$ A ∗ from the theoretical one, in both structures. The findings of this study support the validity and dependability of the proposed alternative model. Furthermore, it may give a new insight into the electrical behavior of the Schottky structures.

New Zn2P2O7, K2ZnP2O7 and KZn1.5P2O7 compounds were synthesized with conventional solid solid reaction method. The optical properties have been studied by using UV–Visible spectrophotometer. The optical band gaps (Eg) were found to be 3.76 eV, 3.39 eV and 3.59 eV respectively. Optical parameters such as refractive index, Cauchy’s parameters and conductivity were deduced. The refractive index fitting in the visible range and the dispersion parameters (E0 and Ed) of these compounds were estimated using the Wemple–DiDomenico model.

In this study, a Cu1.5Mn1.5O4 spinel was successfully synthesized by a sol–gel method at 500 °C for 5 h and characterized by different techniques. X-ray diffraction (XRD), Fourier transformation infrared (FTIR) spectroscopy and Raman spectroscopic analyses confirmed the formation of a spinel cubic structure with the Fdm space group. The SEM proves that the grain size of our compound is of the order of 48 nm. Crystallite sizes determined from three estimates are closer to the grain size obtained from the SEM, indicating the single domain nature of the sample. The optical properties of UV-visible spectroscopy for our sample showed that the gap value is equal to 3.82 eV, making our compound a good candidate for optoelectronic applications. For electrical properties, impedance spectroscopy was performed at a frequency range of 40 ≤ frequency ≤ 106 Hz. This suggested hoping conduction due to three theoretical models. The latter can be attributed to the correlated barrier hopping (CBH) model in region I, overlapping large polaron tunneling (OLPT) in region II and non-overlapping small polaron tunneling (NSPT) mechanism in region III. One dielectric relaxation is detected from the dielectric impedance and modulus, attributed to grain contributions. This behavior was confirmed by both Nyquist and Argand's plots of dielectric impedance at different measuring temperatures.

Impurities are of crucial interest in optoelectronic devices as they affect carrier lifetimes and electrical properties. In view of that, it is important to incorporate certain processing steps to reduce impurities effect on final devices. The aim of this work is to enhance silicon carbide SiC purity for silicon passivation. Low cost method of SiC purification is presented. This method combines three main steps consisting of formation of porous silicon carbide layers by acid vapor etching followed by a photo-thermal annealing at different temperatures. Finally, obtained SiC powder was subject to a chemical treatment to remove porous SiC layer. Effect of gettering temperature on purification efficiency was evaluated by inductively coupled plasma atomic emission spectrometry (ICP-AES). The gettering experiment was performed at 800–950 °C, and optimum results were obtained at 950 °C. SiC purity is improved from 3 N (99.977%) to 5 N (99.999%) with an impurity removal efficiency of 96.56%. Purified SiC was used as a target to synthesize SiC layers using pulsed laser deposition technique (PLD) for optoelectronic devices. The use of intrinsic amorphous silicon carbide (a-SiC) passivating layers was investigated especially by photoconductivity decay technique. Improved SiC target purity leads to a significant enhancement of a-SiC passivating properties attributed to the surface recombination velocity decrease. Electrical properties of a-SiC/c-Si(p) were also studied using I-V and C-V techniques.

Sn3Sb2S6 thin films were elaborated by a vacuum evaporation process, and then they were annealed at 150°C in air for 1 (h). X-ray diffraction results reveal that only the annealed sulfosalt film exhibits a crystalline nature with [416] preferential orientation. The annealing process influences their surface morphology by affecting the size and shape of the Sn3Sb2S6 particles. Then, the thermal conductivity and thermal diffusivity were determined via the theoretical and experimental electro-pyroelectric voltage signals. In addition, we noticed that thermal conductivity and heat capacity values increased by increasing annealing temperature. The electrical and dielectric properties were obtained by impedance spectroscopy technique. At high temperatures, σac conductivity follows the power law of Jonscher, and the σdc variation is the inverse of temperature according to the Arrhenius law. This result indicates that the conduction process is thermally activated, with an activation energy of about 0.813 eV. Finally, we studied some new physical properties of Sn3Sb2S6 thin films; and came to the conclusion that the annealed Sn3Sb2S6 thin film can be promising for solar cell applications.

La0.5Eu0.2Ba0.3−x□xMnO3 (x = 0.00, 0.05 and 0.15) samples were prepared using sol–gel method and annealed at Ts = 750 and 950 °C. The X-ray diffraction technique shows that all samples crystallize in the rhombohedral structure with R-3c space group. Electrical properties of the prepared compounds were investigated using impedance spectroscopy technique in a wide temperature range (80–440 K). The results show a semiconductor behavior for all samples. From dc-conductivity (σdc) analysis, it is observed that increasing barium-deficiency content and sintering temperature improves the electrical conductivity. It is also found that the conduction mechanism is governed by hopping process. Ba-deficiency and sintering temperature affects the activation energy (Ea). From σdc, in the temperature range of 250–480 K and at Ts = 750 °C, it is found that Ea1 decreases from 190 meV for x = 0.00 to 164 meV for x = 0.15. Also, for x = 0.00, Ea1 decreases from 165 meV at Ts = 750 °C to 145 meV at Ts = 950 °C. Complex impedance analysis indicates the presence of non-Debye type relaxation. Such analysis confirms the contribution of grain boundary on the conduction. The activation energy Ea2 deduced from dc-conductivity matches very well with the value estimated from relaxation time (Eaτ) indicating that relaxation and transport mechanisms are related to the same defect.