Stannous-based perovskite oxide materials are regarded as an important class of transparent conductive oxides for various fields of application. Enhancing the properties of such materials and facilitating the synthesis process are considered major challenging aspects for proper device applications. In the present paper, a comprehensive and detailed study of the properties of spray-coated CaSnO3 thin films onto the Si(100) substrate is reported. In addition, the substrate effect and the incorporation of rare-earth Nd3+ on engineering the characteristics of CaSnO3 thin films annealed at 800 °C are included. X-ray diffraction (XRD) analysis results revealed the orthorhombic structure of all the samples with an expansion of lattice spacing as the substitution of Nd at the Ca site increased. The Raman and FT-IR analysis further confirmed the structural results collected via the XRD analysis. Surface scanning using field-emission scanning electron microscopy revealed the formation of quasi-orthorhombic CaSnO3 grains with an increase in size as dopant content increased. Energy-dispersive X-ray analysis allowed quantification of the elements, while atomic mapping permitted visualizing their distribution along the surfaces. UV-visible spectroscopy and first-principles calculations using density functional theory (DFT) were conducted, and a thorough investigation of the optical and electronic properties of the pure material upon Nd3+ insertion was provided. Electrical properties collected at room temperature revealed a growing conductivity upon doping ratio increase with a simultaneous enhancement in the carrier concentrations and mobility. The findings of the present work will help facilitate the synthesis procedure of large-area stannous-based perovskite oxide thin films through simple and efficient chemical solution methods for optoelectronic device applications.

Herein, the modifications on the properties of the ZnS thin films by copper doping with various concentrations Zn 1−x Cu x S (x = 0, 1, 3, and 5 at %) have been studied. The properties of pure ZnS have been provided for the purpose of comparing different thin films. All samples have been synthesized using the simple ultrasonic spray method on glass substrates at 200 °C and characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and ultraviolet–visible (UV-Vis) spectroscopy. Structural analysis revealed that the films are polycrystalline fitting well with the ZnS hexagonal wurtzite structure with the (002) direction as a preferential orientation for all the films except for the (5 at%) concentration that preferred (100) orientation. An increase in the grain size was observed through surface scanning as the dopant percentage increased. The deposited films possessed an average optical transmittance in the range of 86% at the visible region combined with a high absorption coefficient (~ 10 5  cm −1 ), while a slight decrement was observed on the optical band gaps of Zn 1−x Cu x S films passing from 3.93 eV to 3.64 eV as dopant content increased. The ab initio calculations revealed a major enhancement in the properties of ZnS as the Cu content increased. The findings obtained in the current study display that when the copper percentage is highest, the Zn 1−x Cu x S thin film can be a suitable candidate as an absorber layer in thin film solar cells.

Delafossite materials are considered to be a promising range of transparent conductive oxides for optoelectronic applications. The complications that have held back their implementation in practical devices lie in the complex growth methods that are required and in the formation of undesirable secondary phases. Herein, a fast, simple, and low-cost deposition method allowing the deposition of high-quality 2H-CuFeO2 nanostructured thin films is employed. The effect of Sr doping on the properties of spray-coated CuFeO2 thin film annealed at 850 °C is reported. X-ray diffraction (XRD) analysis revealed the delafossite structures of all the samples corresponding to the 2H-CuFeO2 phase. The lattice spacing decreased with increasing substitution of Sr at the Cu site. Raman analysis further authenticated the structural results collected via XRD analysis. Surface scanning using field-emission scanning electron microscopy revealed the formation of nanostructured CuFeO2 thin film possessing high crystalline quality, with the nanocrystal size increasing as the dopant content was increased. Energy-dispersive X-ray analysis allowed the quantification of the elements content via determining the ratios of the main elements as well as the dopant content in each sample. The optical properties of the samples showed strong light absorption in the visible region with a decrease in the band gap values with Sr insertion. First-principles calculations using density functional theory (DFT) were conducted to strengthen the experimental findings regarding the nature of the bonds in the hexagonal lattice of the CuFeO2 compound and the effect of Sr doping on its characteristics. The electrical properties measured at room temperature revealed p-type conductivity with tunable resistivity, while the samples displayed increased electron mobility as a function of the dopant content. Consequently, our work introduced an efficient and cost-effective synthesis route for the preparation of high-quality nanostructured 2H-CuFeO2 thin films, paving the way to facilitate further device applications.

ABSTRACT In this study, undoped ZnO, (Sr, Mg) co-doped ZnO (SMZO) thin films were synthetised on heated glass substrates at a temperature of 250°C by using ultrasonic spray technique. Doping strontium (Sr) and magnesium (Mg) into zinc oxide (ZnO) offers an important way to modify various properties. X-ray diffraction (XRD) confirmed that the films exhibited the hexagonal wurtzite structure of ZnO with a favored orientation along (002) plane . Scanning electron microscope (SEM) showed a strong change in the surface morphology while Energy dispersive X-ray spectrometer (EDX) and mapping confirmed the purity of the films . UV-Visible studies demonstrated that the optical transmittance was improved to an average value above 94% and that Mg-doping induces an increase of the band gap indicating high optical quality of the films. From the fabricated films, SMZO3 is the most appropriate for optoelectronic applications where a low resistivity and high figure of merit were obtained.

The inorganic stannous-based perovskite oxide SrSnO3 has been utilized in various optoelectronic applications. Facilitating the synthesis process and engineering its properties, however, are still considered challenging due to several aspects. This paper reports on a thorough investigation of the influence of rare-earth (praseodymium) doping on the microstructural and optoelectronic properties of pure and Pr-doped SrSnO3 perovskite oxide thin films synthesized by a two-step simple chemical solution deposition route. Structural analysis indicated the high quality of the obtained phase and the alteration generated from the insertion of impurities. Surface scanning illustrated the formation of homogenous and crack-free SrSnO3 thin films with a nanorod morphology, with an augmentation in size as the dopant ratios increased. Optical properties analysis showed an enhancement in the samples optical absorption with wide-range bandgap tuning. First-principles calculations revealed the exchange interactions between the 3d-4f states and their impact on the electronic properties of the pristine material. Hall-effect measurements revealed an immense decrement in the resistivity of the films upon increment of doping ratios, passing from 7.3 × 10-2 Ω cm for the undoped sample to 4.8 × 10-2 Ω cm for 7% Pr content, while a reverse trend was observed on the carrier mobility, rising from 2.5 to 7.6 cm2 V-1 s-1 for 7% Pr content. The results emphasized the efficiency of the simple synthesis route to produce high-quality samples. The current findings will contribute to paving the way towards expanding the utilization of simple and cost-effective chemical solution deposition methods for the fast and large area growth of stannous-based perovskite oxides for optoelectronic applications.

The thin films Fe doped copper sulphide Cu1−xFexS (CFS) (x = 0.01, 0.03, 0.05, and 0.07) were elaborated by spray pyrolysis deposition technique. The characterization by XRD and SEM of the thin films shows a Covellite CuS single phase without formation of other phases. The structure is a simple hexagonal with unit cell dimension, a = b = 3.79 Å and c = 16.34 Å. The Analysis of the UV–Vis spectra reveals that the energy band gap has been decreased from 2.47 to 1.98 eV with the increase of Fe concentration. The absorption coefficients of CFS films have increased from 1.155 × 105 to 1.712 × 105 cm−1. It has demonstrated that a right band gap with a right band edge alignment at a pH value for Fe-doped CFS can boost the material application as a photocatalyst for the visible light. According to this study, CFS (0.07) thin films for a pH = 3 solutions is a promising material for photocatalysis application for water splitting to hydrogen-oxygen production. Nevertheless, we demonstrate that the formation of straddling gap heterostructure for CuS and CFS for a pH solution between 7 and 8 induces the production of oxygen and hydrogen.

In the last two decades, the terms waste management and climate conservation have become major worldwide issues with global warming and its opposing sides on the future of the planet. The main purpose of this study is the modeling of Anaerobic Digestion (AD) that can be utilized to analyze various operational strategies in order to recover biogas from Maize Waste (MW). The production of methane is the go of this paper, which requires the inclusion of biological and Physico-chemical models in order to describe the whole process of methanization. One of the best choice in the modeling of such biological issues is the phenomenological model of Anaerobic Digestion (AD), which is the most complete model for wastewater treatment. This model is called ADM1, and it is an integrated model that describes very well the transformation of the Organic Matter (OM) into soluble components, then into biogas as the final phase of this biological conversion. The modeling tools for anaerobic degradation make the subject of this study. The completion of the ADM1 model is done by the resolution of systems of Differential Equations (DE) by a numerical method. In this study, the Runge-Kutta method is used to resolve the ADM1 model.

In this paper, a combination of DFT study and Monte Carlo (MC) simulations has been performed on Gd compound which undergoes a second–order phase transition from ferromagnetic state to paramagnetic one. For this single material, the temperature-dependent total magnetization and magnetic susceptibility have been calculated and are revealed that the Curie temperature is acceptable concurrence with the experimental value. Furthermore, it was showed that under an external magnetic field of 2 Tesla (T), MCE of Gd compound around its Curie point in regard to the maximum value of magnetic entropy change ( − Δ S m a g M a x ), agrees well with the experimental one. Besides, the Relative Cooling Power (RCP) values are found to be 34.37, 69.18, 90.74 and 128 J.kg−1 under different magnetic fields of 0.5, 1.0, 1.5 and 2T, respectively. All findings which are presented here indicate that DFT calculations and Monte Carlo simulations can be efficiently used to predict the magnetic and magnetocaloric features of Gd and related alloys.

The present study is carried out for investigating the half-metallic ferromagnetic behavior of Cr and Fe doped and co-doped GaN, respectively. To this end, ab-initio calculations using the Korringa-Kohn-Rostoker Green's function method coupled with the coherent potential approximation have been employed. In the background to make the study more useful, the first-principles computations were added and merged to the mean-field approximation and the Monte-Carlo simulation for the co-doped compound. Several variations were perceived in the results as in the bandgap energy, the energetic location of the transition-metal 3d band and the X-ray absorption spectra. Besides, the stability of the system between the ferromagnetic and the spin-glass states is studied. Finally, we have integrated as input parameters in the classical Ising model by Monte-Carlo simulation, the exchange interactions obtained from ab-initio calculation, in order to confirm the half-metallic ferromagnetic states with high Néel temperature.

ABSTRACT In the present work, SnxSy thin films have been deposited into heated glass substrates at 350°C from different molar concentrations (x = 0.05M, y = 0; 0.03; 0.05; 0.07; 0.1M) by means of a spray pyrolysis technique. Firstly, it was found that optimum molar concentration of the precursor to obtain device quality SnS thin film is x = 0.05 M and y = 0.05 M. Moreover, the findings detected by X-ray diffraction (XRD) analysis show that the film crystallized in the orthorhombic crystal structure with a preferred grain orientation along (111) plane. Furthermore, the optical characterization revealed that the average optical transmission had been significantly reduced and the band gap value is 1.8 eV as well as a very high absorption coefficient (105/cm). Besides, the electrical properties study exhibited that the sample is p-type and the value of the electrical resistivity of SnS film is 2.75 × 10−2 (Ω.cm).

This work presents the synthesis of a new quaternary compound Cu2CoGeS4 (CCGS) thin film for the first time combined with first-principles calculations (DFT, WIEN2k). The synthesis was done via spray ultrasonic of Cu-Co - Ge precursors onto glass substrate followed by high - temperature (500 degrees C) sulfurization under inert atmosphere (Ar). A near 2:1:1:4 stoichiometry of Cu2CoGeS4 was confirmed from EDX analysis. X- Ray- Diffraction(XRD) analysis confirmed the formation of polycrystalline Cu2CoGeS4 (CCGS) thin film with a tetragonal stannite structure(1 (4) over bar 2m). Raman spectroscopy confirmed the purity of the film and showed the presence of the characteristic predominant peak (339 cm(-1)) of the tetragonal stannite structure. The band structure displayed a direct band - gap. The experimental and theoretical optical band gaps were found to be about 1.75 eV with high absorption-coefficient in the visible region of the solar spectrum. Electrical measurement confirmed the p-type conductivity with a resistivity of 0.89(Omega.cm(-1)) and a carrier concentration of 4.6 10(16 )cm(-3). These results and the photoresponse measurement make the Cu2CoGeS4 (CCGS) a potential material for solar cell application and will draw the attention to develop this material in several other applications.

In this paper, we consider the electronic and magnetic proprieties of five rare-earths (RE = Pr, Pm, Sm, Dy, and Tm)-doped Tin (IV) oxide semiconductor Sn1 − xRExO2 (x = 0.10) in the rutile structure. The presence of the 4f orbitals in our structures pushes us to choose the local density approximation with Self-interaction-corrected (LDA-SIC) to improve the obtained results. We also discuss the critical temperature retrieved from the study the total magnetizations and the susceptibilities using Monte Carlo simulations for each rare-earth element used.

In this work and for the first time, a near stoichiometric Cu2MnGeS4 thin film have been synthesized via spray ultrasonic deposition of Cu-Mn-Ge precursors onto glass substrate at 180 degrees C, with post-sulfurization at 500 degrees C under Ar-atmosphere. The synthesis onto molybdenum substrate gave only secondary phases. Various characterization techniques were carried out. The results were discussed, completed and compared with the theoretical study (WIEN2k). X-Ray-Diffraction (XRD) and Raman spectroscopy analysis confirmed the formation of wurtz-stannite (orthorhombic) Cu2MnGeS4 (CMGS) structure (Pmn21). The presence of Cu-Mn-Ge-S was confirmed by Energy Dispersive X-ray spectroscopy (EDX). A direct band-gap was confirmed from DFT calculation. The optical band gap was found in the range of 1.6 to 1.72 eV (UV-visible measurement, DFT calculation) with high absorption coefficient (> 10(4)cm(-1)) in the visible range of the solar spectrum. The results make Cu2MnGeS4 (CMGS) a promising material for solar cell application. (C) 2020 Elsevier B.V. All rights reserved.

Crosstalk is an undesirable phenomenon having a negative impact on the electroacoustic performance of ultrasonic transducer arrays, utilized in medical imaging and NDT applications. Indeed, when one element of a transducer array is excited, it generates parasitic voltages and/or displacement fields on the adjacent passive elements. Consequently, these interactions between elements (crosstalk) are responsible for anomalous in the electromechanical behavior of the transducer array. The goal of this paper is to investigate the effects of the electrical limit conditions, i.e. when the passive neighboring elements are considered in Open-Circuit or Short-Circuit (as in the case of the crosstalk’s active cancellation techniques), on the physical behavior of the array elements. This research work also studies the impact of the limit conditions on the crosstalk’s evaluation. In this context, a piezoelectric transducer array composed of seven elements made of PZ27 ceramic is modeled using a two-dimensional finite elements method. A prototype is then fabricated and experimental measurements, i.e. electrical impedance, displacement, and crosstalk measurements are realized and successfully compared to the numerical results.

Ultrasonic transducer arrays are generally composed of several piezoelectric elements arranged in 1D or 2D ways. Crosstalk is an undesirable phenomenon decreasing the performance of these devices. It generates parasitic displacements at the elements' radiating surfaces, which changes the directivity of the array. Furthermore, the transducer's displacement plays a critical role in terms of the focal area and transferred intensities. The objective of this paper is to characterize a piezoelectric array composed of seven-elements made of PZ 27 ceramic experimentally. It investigates the effects of the crosstalk phenomenon on the array's performance in particular. The results have shown that the array's elements vibrate mainly in thickness mode, but the displacement is not uniform along their length due to the contribution of a parasitic length mode. Moreover, the major parasitic displacements are obtained on the neighboring passive elements: about-7.3 dB,-11 dB, and-12 dB, on the first, the second, and the third elements, respectively.

Cu2NiGeS4 (CNGS) thin film has been obtained for the first time. The synthesis was done via spray ultrasonic deposition of Cu - Ni - Ge precursors (aqueous salt) onto glass substrate (Ts = 180 degrees C), followed by high-temperature sulfurization under inert atmosphere (500 degrees C - Ar - S-8). X - Ray - Diffraction (XRD) and Raman spectroscopy analysis confirm the formation of polycrystalline Cu2NiGeS4 (CNGS) with tetragonal kesterite (I (4) over bar) structure. A near stoichiometry 2:1:1:4 of Cu - Ni - Ge - S was confirmed by Energy Dispersive X - ray Analysis (EDX). The Hall Effect measurement reveals the p - type semiconductor of Cu2NiGeS4 thin film. The theoretical calculation based on the density functional theory (DFT) shows a direct band gap (band structure). The experimental and theoretical optical band gap found to be in the range of 1.60-1.8 eV with high absorption coefficient (>10(4)cm(-1)) in the visible spectra. The obtained results will be a basis to develop these materials in the field of photovoltaics.

In the present paper, we investigate in detail the Gd doping effect on the properties of the chemically prepared SrSnO3 thin films. Unlike previous preparation attempts that utilized a very sophisticated vacuum methods and high annealing temperature, a very simple path was followed by employing the simple ultrasonic spray method with an annealing process at only 800 degrees C, resulting a high quality films. The crystallographic identification using XRD analysis confirmed the formation of SrSnO3 phase crystallizing in the orthorhombic structure with Pbnm space group. The percentage of the gadolinium doping affected the obtained structure majorly after passing the 5%. Structural properties were further investigated with Raman and FT-IR analysis confirming the results obtained by the XRD. Morphology and chemical composition of Gd-doped SrSnO3 thin films were evaluated using a field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectrometer (EDX). The surface scanning shows an amelioration in the morphology of the films as dopant ratio increased, while EDX and mapping analysis confirmed the purity of the resulted films with the presence of the dopant element. The Gd-doping effect on the optical properties was noticed through the decrement of the transparency of the films and the dropping of the band gap from 3.88 to 2.85 eV for the 7% of dopant content. The first principles calculations revealed a major modifications on the electronic and optical properties of SrSnO3 generated by the 4f state of Gd. A remarkable variation of the band gap was measured decreasing from 4.08 eV to 2.17 eV, which emphasizes our experimental findings.

Layered charge-density-wave (CDW) materials exhibit a lot of interesting aspects for their potential in a variety of device applications. So, a good understanding of their properties may enable the better development of new devices based on them. We address in this paper a study of the dynamic properties of CDW two-dimension electronic crystal in the presence of weak interchain interaction. This study was done through numerical experiments based on the generalized Fukuyama–Lee–Rice (FLR) model. One of the results of this Letter showed that the time-dependent spatially averaged velocity exhibits the steady-state regime characterized by a series of quasi-periodic fluctuations. Moreover, it was found that the increase in the weak interchain interaction effect reduces the NBN amplitude and normalized excess conductivity. All findings accessed here were discussed in the context of the inhomogeneous nature of CDW’s dynamics, damping mechanism as well as the attenuation of phase solitons which are nucleated when the CDW’s slide.

We report the synthesis and characterization of the stannous based CaSnS3 chalcogenide perovskite thin film prepared through simple chemical route, and providing a detailed experimental and theoretical investigation of such material. Several attempts were performed to reach optimal conditions, starting from the oxide thin film deposition to the sulfurization process. The crystal identification using X-ray diffraction (XRD) and Raman analysis indicated the formation of a polycrystalline film with no secondary phases detected within the detection limits of the characterization methods employed. Field emission scanning electron microscopy (FE-SEM) screening displayed a notable enhancement on the resulted surfaces, while energy dispersive X-ray spectrometer (EDX) mapping showed the drastic change in the sulfur content with good distribution and homogeneity of the elements on the obtained surfaces. Optical measurements indicated a direct band gap of 1,72 eV in good agreement with our theoretical calculation using the generalized gradient approximation of the modified Becke-Johnson (GGA-mBJ), alongside with an absorption coefficient in the order of 10(5) cm(-1). The Hall effect measurements revealed a p-type conductivity and a carrier concentration of 1.216.10(17)cm(-3) with an outstanding carrier mobility recorded at 1.314.10(2) cm(2) V(-1 )s(-1). The photoresponse test was conducted by collecting the Current-Voltage (I-V) variation in dark and under illumination, demonstrating a strong photoabsorption with high stability in ambient atmosphere. The results set the foundations to further investigate the stannous based chalcogenide perovskites as a promising materials for optoelectronic applications. (C) 2020 Elsevier B.V. All rights reserved.

Herein, teh first TEMPprincipal calculations and Monte Carlo Simulation (MCS) were performed to investigate teh magnetic and magneto-caloric properties of PrSi compound. Teh partial magnetic moment of Pr (m(Pr)), and teh exchange interactions parameters (J(1), J(2)) are found to be m(Pr )= 2.8 mu(B), J(1) = 1.707 meV and J(2) = 1.312 meV, respectively. Through teh MCS, it was found dat teh Curie temperature value (T (c)) from ferromagnetic to paramagnetic state is T (c) = 55 K, which is in good agreement wif teh experimental value which is 54 K. Moreover, it was established dat a slight increase in teh applied magnetic field leads to a high increase in teh magnetic entropy from 4.4 J/kg K for h = 1 T to 13.7J/kg K for h=5 T. Furthermore, teh values of adiabatic temperature change and relative cooling power (RCP) obtained for h = 5 T were found to be 3.6 K and 550 J/kg, respectively.