Values Of Dislocation Density Research Articles

Thickness effects on the physical characterization of nanostructured CuO thin films for hydrogen gas sensor

In these studies, radio frequency (RF) magnetron sputtering was used to produce nanostructured CuO thin films on glass bases with different thicknesses of (250, 300, and 350 nm). X-ray diffraction (XRD) analysis of these films revealed a polycrystalline structure with a preferred peak along the (111) plane. The Scherrer formula was used to compute the grain size. It was found that the average grain sizes are 10.78 nm, 11.36 nm, and 11.84 nm for film thicknesses of 250, 3000, and 300 nm, respectively, while the dislocation density and strain values decline. The surface roughness decreased from 9.30 nm to 4.71 nm as the thickness increased, according to atomic force microscopy (AFM) data. As the thickness of the film grew, the root mean square (RMS) roughness likewise decreased from 9.18 nm to 4.29 nm. The homogenous, semi-spherical structure comprises uniformly distributed particles, as demonstrated by SEM images. The optical properties of the grown films showed that the absorption coefficient considerably increased with film thickness. Transmittance, band gap, refractive index, and extinction coefficient all decrease with increasing film thickness. The hydrogen gas measurements, indicated a reduction in sensitivity as the thickness and gas concentration increased at 30°C.

The effect of seed layer cycles on the structural, optical, and morphological properties of ZnO nanorods.

In this study, ZnO seed layers with different cycles were formed on glass substrates by the sol-gel technique, and ZnO nanorods were grown on them by the hydrothermal method. Morphology and the structural characterization of the seed films and the ZnO nanorods are carried out by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction techniques. In addition, to investigate the effect of seed layer deposition cycles on the optical properties of the ZnO nanorod arrays, UV/visible spectrophotometer and photoluminescence (PL) measurements were performed. The changes in structural and optical parameters such as dislocation density, strain, crystallite size, and optical band gap values on each seed layer deposition cycle were examined. The highest optical band gap and crystallite size were obtained for ZnO nanorods with 4 cycles seed layer as 3.22 eV and 63.6 nm, respectively. Also, in the PL spectrum, the largest ratio of UV-emission region to weak-visible emission region was obtained in ZnO nanorods having 4 cycles. In addition, the glucose detection properties of ZnO nanorods having 4 cycles were investigated using the PL measurements and it was found that UV-emission peak intensity of ZnO nanorods decreased as the glucose concentration increased from 8 to 40 mM. The results show that the number of deposition cycles of the seed layer has a strong influence on the orientation, crystal quality, and optical band gap of the growing ZnO nanorods, as well as significantly affecting their morphological properties. RESEARCH HIGHLIGHTS: High quality ZnO nanorods were grown on glass substrates by hydrothermal method. The effect of ZnO seed layer cycles on the structural, optical, and morphological characteristics of ZnO nanorods grown on were examined. It was found that the number of cycles of the seed layer is a critical parameter for growing quality and well-aligned ZnO nanorods.

Assessment of phenomenological models for Indentation Size Effect (ISE) through physically based dislocation density evolution

The depth dependent hardness, referred to as indentation size effect (ISE) has gained considerable attention. ISE is attributed to the strain gradient caused by the inhomogeneous strain distribution beneath the indenter tip. The depth dependence of hardness is phenomenologically accounted using an appropriate length scale parameter. The Unified model is one such model that is built on Nix–Gao’s model and focuses on integrating various length scale parameters resulting from both microstructural and geometrical effects. One aspect of the current work is to assess the applicability of the Unified model to a material like bulk Nickel with a history of cold work. Also, the physics of ISE in metals can be related to the dislocation mean free path influenced by strengthening mechanisms. Past attempts are scarce to quantify the ISE through the microstructure variables. In the present work, an attempt has been made to simulate the nanoindentation test using a dislocation density based constitutive model. The objective of this study is to establish a correlation between the equivalent plastic strain resulting from deep depth indentation (which does not exhibit a size effect) and an equivalent dislocation density. The dislocation density here serves as a state variable that describes the microstructure-dependent mechanical behaviour. The modified KME, a dislocation density-based model, is incorporated as a user subroutine in a commercial finite element solver. It has been proven to accurately predict the indentation behaviour at substantially large depths, which aligns well with the predictions of the Unified model or experimental observations. The good correlation between the value of effective dislocation density and equivalent plastic strain in the plastic zone underneath the indenter assures to extend the use of dislocation density as a state variable to predict ISE.

Influence of deposition temperature on the defect mediated persistence photo-conducting behaviour of spray coated Zn0.96Nd0.04O thin films

The incorporation of Neodymium into ZnO lattice enhances the photo conducting property of the deposited films which are strongly dependent on preparation conditions. Hence, the comprehensive work carried out to understand the influence of deposition temperature (300 °C–500 °C) on the persistence photoconductivity of Zn0.96Nd0.04O films deposited on glass substrates using spray pyrolysis method. The maximum crystallite size of ∼16.3 nm with minimum dislocation density and strain values were noticed for the films deposited at 450 °C. The mixed fibrous -granular morphology was noticed in the deposited films. The maximum transparency above 90 % in the visible region and an increased bandgap of 3.42 eV was observed in the films deposited at 450 °C. The percentage of defects were calculated using the area under the curve of photoluminescence spectra. The charge carrier density of 1.7 × 1017 cm−3, mobility of 62.8 cm2/Vs and lesser resistivity of 1.3 × 102 Ω cm were noted for the films deposited at 450 °C. Under the illumination of UV light, the photocurrent of Zn0.96Nd0.04O films deposited at 450 °C increased by four orders. The persistence in the photo resistance was due to the presence of Zn and O related defects, which acts as trap centres. The variation of photo resistance with time indicates the films deposited at 450 °C has faster photo response due to the faster electron – hole recombination process. The maximum photocurrent at 360 nm was noted for the films synthesized at 450 °C due to improved crystallinity with stoichiometry nature of the films. Hence, the Zn0.96Nd0.04O films deposited at 450 °C suitable for light dependent resistor and fixed wavelength UV photodetector applications.

Investigation of the effect of ball-burnishing treatment applied to Al 7075-T6 alloy on mechanical and crystallographic properties

ABSTRACT In this study, the mechanical, microstructural, and crystallographic effects of ball-burnishing applied to Al 7075-T6 alloy at 0.15–0.30 mm penetration depth, 0.15–0.30–0.60 mm/rev changing feed rates and 100–200 rpm range were investigated. After the ball-burnishing processes were carried out in different parameters, surface roughness measurements were applied to determine the surface qualities, and hardness and impact energy tests were applied to characterise the mechanical properties. Dislocation density and texture coefficient values were calculated by determining the crystallographic properties using X-ray diffraction. It has been determined that the ball-burnishing process directly affects the surface roughness, depending on the increasing rotational speed and feed rate. As a result of microstructural investigations, the average grain size decreased with increasing amount of deformation on the sample surface. At 200 rpm ball-burnishing parameter, the surface hardness of the sample increased by approximately 41% compared to the initial state and was measured as 265 HV2. It was determined that the ball-burnishing process did not positively affect the impact of the toughness of the alloy. The reason for this is that the roughness and scratches on the surface caused by the ball-burnishing process have a notch effect, increasing the crack formation and propagation speed.

Selective Epitaxy of Germanium on silicon for the fabrication of CMOS compatible short-wavelength infrared photodetectors

Here we present the selective epitaxial growth of Ge on Si using reduced pressure chemical vapor deposition on SiO2/Si solid masks realized on 200 mm Si wafers, aiming at manufacturing integrated visible/short-wavelength infrared photodetectors. By a suitable choice of the reactants and of the process conditions, we demonstrated highly selective and pattern-independent growth of Ge microstructure featuring high crystalline quality. The Ge “patches” show a distinct faceting, with a flat top (001) facet and low energy facets such as e.g. {113} and {103} at their sidewalls, independently on their size. Interdiffusion of Si in to the Ge microcrystals is limited to an extension of ∼20 nm from the heterointerface. The Ge patches resulted to be plastically relaxed with threading dislocation density values better or on par than those observed in continuous two-dimensional Ge/Si epilayer in the low 107 cm−2 range. A residual tensile strain was observed for patches with size >10 μm, due to elastic thermal strain accumulation, as confirmed by μ-Raman spectroscopy and μ-photoluminescence characterization. Polarization-dependent Raman mapping highlights the strain distribution associated to the tridimensional shape. On this material, Ge photodiodes were fabricated and characterized, showing promising optoelectronic performances.

Dislocation density-based fatigue approach for structural steel details

Global approaches have been the main procedure for designing structural details and components under fatigue loading. This procedure is easy to apply but it disregards not only the effect of the material type but also the influence of the geometry. On the other hand, local approaches rely on the specific local parameters that can be assessed for each type of material and detail geometry. The parameters derived from low cycle fatigue (LCF) tests are the most common damage parameters used to predict fatigue life and establish fatigue design approaches. Recently, Huffman proposed a fatigue damage model based on strain energy density and dislocation density of the material. In this regard, two structural steels were selected to perform a metallographic and mechanical characterization aiming to determine fatigue life parameters and dislocation density. The fatigue behavior of these materials was evaluated using strain-Morrow, SWT, and strain-Huffman parameters, and the dislocation density values obtained by XRD were analyzed. Additionally, experimental results from fatigue tests on structural details (plate with hole) were compared with fatigue life predictions based on each local model. It was found that the Huffman model based on dislocation density is a reliable approach to predict the fatigue life of structural steel details.

Defect structure of high-resistance CdTe:Cl single crystals and MoOx/CdTe:Cl/MoOx heterostructures according to the data of high-resolution X-ray diffractometry

Clorine doped CdTe single crystals (CdTe:Cl) were grown by the traveling heater method. MoO x /CdTe:Cl/MoO x films were deposited using the reactive magnetron sputtering technique. The defect structure of the obtained single crystals and heterostructures was investigated using high-resolution X-ray diffractometry. The optimized models of dislocation systems in the CdTe:Cl single crystals were constructed based on the Thompson tetrahedron. The distribution of the intensity of diffracted X-rays as a function of reciprocal space coordinates and rocking curves was analyzed using the kinematic theory of X-ray scattering in real crystals. The experimental and theoretically predicted values of the helical dislocation densities in the CdTe:Cl and MoO x /CdTe:Cl crystals with perfect and mosaic structures were compared. Two-fold increase in the dislocation concentration in the MoO x /CdTe:Cl heterostructures as a result of compression deformations of the CdTe:Cl crystal lattice was found. The ~0.1 μm thick transition deformed layer at the boundary between the MoO x film and CdTe:Cl single crystal significantly affects the electrical and spectroscopic properties of the obtained systems as the materials for γ-radiation detection.

Effects of Pre-Strain and Tempering on Mechanical Properties in High-Strength Martensitic Steels

Effects of pre-strain and tempering on mechanical properties in high-strength martensitic steels were investigated. In this study, strain tempering (ST) and quenching and tempering (QT) martensitic steels were prepared, and their mechanical properties were studied. In the tensile tests at the deformation temperatures between 296 and 573 K, the ST sample increased both of tensile strength (TS) and uniform elongation (U.El) from 473 to 523 K whereas the QT sample increased U.El with little change of TS. From the in situ neutron diffraction experiments, stress partitioning to the bcc phase increased with an increase in the deformation temperature from 296 to 523 K. The difference of phase stress between the bcc and cementite phases decreased with increasing the temperature because of a decrease in the cementite strength. In the ST sample, Pre-straining of 0.5% increased YS at 296 K with slight work hardening. The initial value of dislocation density (ρ) decreased at 523 K but ρ increased significantly after yielding, leading to better combination of TS and U.El. The combinations of pre-strain, tempering, and deformation temperatures have changed ρ before deformation and the increase of ρ after yielding of the martensitic steels.

316L-Si Austenitic Stainless Steel Elaborated by Additive Manufacturing Process: Porosity and Dislocation Density Estimation

This investigation estimated porosity and dislocation density in austenitic stainless steel 316LSi thin walls fabricated by Cold Metal Transfer Wire and Arc Additive Manufacturing (CMT-WAAM). Porosity density was calculated using ImageJ software. MAUD software (Materials Analysis Using Diffraction) was used to analyze the microstructural parameters and dislocation density. The density of pores and microstructural parameters of 316LSi alloy exhibit typical values of AM conditions. The porosity values oscillate between 2.80 to 3.48 %. The obtained dislocation density values are 5.0 e+12, 4.3 e+12, and 3.2 e+12 for 2.4 e+12 m-2 for 70, 80, 90, and 140 A current source, respectively. In 316LSi thin walls, the increases in the current input in CMT-WAAM are accompanied by the very lowest decrease in the dislocation density state.

Dislocation-density-related constitutive model and its applicability to cyclic deformation and damage behavior of 316LN SS at 823 K

In the present investigation, an in-depth understanding of the relationship between dislocation kinetics and cyclic plasticity, along with the description of yield asymmetry behavior during loading and unloading in nuclear grade 316LN austenitic stainless steel at 823 K, was examined by employing a constitutive framework using the evolution of physically-based internal-state variables. The formulation encompassed a set of first-order simultaneous differential equations that governed the evolution of dislocation density, mean free path of dislocations, and back stress. These variables were interdependent with the power law which described the kinetics of plastic strain rate. The evolution equations were numerically integrated, and the simulated data were fitted to the experimental data up to stabilized cycle at a temperature of 823 K and total strain amplitudes of ±0.004, ±0.006, ±0.008 and ± 0.010. The predicted cyclic stress response as a function of the cyclic number displayed the continuous cyclic hardening from the first cycle to the initiation of stabilized cycle. Further, good agreement between the predicted and experimental hysteresis loops was found at different cycle numbers. The predicted dislocation density and tensile peak values of back/effective stress increased with cyclic hardening and approached the value of saturation at the stabilized cycle. On the other hand, a rapid decrease in mean free path with cycle number was noticed. An increase in total strain amplitude resulted in a systematic increase in dislocation density, peak stress, back stress and effective stress. At the total strain amplitudes above ±0.006, the predicted higher rates of dislocation accumulation and annihilation, and the faster evolution rate of back stress towards saturation led to the development of stable dislocation substructure configurations with a clear distinction between dislocation high/low dense regions. Furthermore, the applicability of the model was extended by including an empirical relationship between the damage variable and cycle number within the power law, thereby enabling predictions of the cyclic stress-strain response beyond the stabilized cycle.

Revealing 3D intragranular micromechanical fields at triple junctions

Triple junctions, intersections of three or more grains in polycrystalline solids, are known locations of potential stress concentration and strain localization. In this work, intragranular lattice curvatures and elastic strains are measured at triple junctions via a novel zoom-in style combination of synchrotron X-ray techniques. Additionally, this work revisits the impact of including elastic strain gradients while calculating the dislocation density within embedded grains via the Nye dislocation tensor. Without elastic strain gradients, the dislocation density is underestimated at a hotspot by 27% of the maximum dislocation density value. Spatial regions near triple junctions are found to contain both the highest values of the intragranular misorientations metrics and generally higher values than grain boundaries (between two grains). A heterogenous distribution of intragranular misorientation, elastic strain, and dislocation density is measured within a grain along a single triple junction line, and the triple junction line end points (quad points) exhibit substantially different micromechanical fields. This work provides a unique 3D view of triple junctions within individual grains and highlights their spatially heterogenous intragranular micromechanical response along triple junction lines, especially when compared to relatively less complex behavior along grain boundaries. While a grain averaged example is provided of intergranular strain across grains, several examples of intragranular strain were visualized near a triple junction. The combined analysis of intragranular lattice curvature (associated with strain metrics) and elastic strain (associated with stress) provides a more complete characterization of the 3D sub-grain fields than previously reported.

Analysis of dominant and intense XRD peak of (111) plane of ZnS nanocrystals for microstructural study through single line Voigt method: Calculated low dislocation density value emphasizes larger stacking of (111) plane

In this work, a wet chemical synthesis method has been used for the preparation of ZnS nanocrystals using the precursor Zn(NO3)2 (Zinc Nitrate) and Na2S (Sodium sulfide), where 3-Mercaptopropionic acid has been used as a capping agent. Morphological characterization of the prepared ZnS nanocrystals has been performed through HR-TEM and FE-SEM analysis and the average particle size has been obtained as approximately 26 nm. The HR-TEM image also suggests the formation of smooth crystalline ZnS nanoparticles with dominance of the (111) plane. The XRD pattern firmly indicates dominance of (111) crystalline planes over the other planes. For this, different microstructural properties of prepared ZnS nanoparticles have been studied considering only the dominant (111) diffraction peak using single line Voigt method. Finally, the average particle size calculated from morphological analysis has been compared with the crystallite size calculated by XRD analysis through the Single line Voigt method. Calculated dislocation density value indicates presence of less defects states in the sample and confirms the growth of ZnS nanoparticles in a particular direction of (111) plane with pure crystalline nature.

Interfacial investigations on the microstructure evolution and thermomechanical behavior of explosive welded CLAM/316L composite

In this paper, a comprehensive study combined multiple characterizations and SPH numerical simulation was conducted to investigate the microstructure evolution, extreme thermomechanical behavior and consequences of the explosive welded CLAM/316L interface. The interfaces of the two welding materials underwent remarkable temperature rise and rapid cooling under high-speed collision conditions, forming a tight bond that presents a wavy structure with vortices. The SPH simulation adequately reproduced the heating and cooling process of the interface during explosive welding, revealing the high heterogeneity of the thermodynamic behavior during the impact process. Furthermore, the EBSD analyses showed the perplexing evolution of crystal structure at the bonding interface with vortex, including ultra-fine grains, columnar grains, equiaxed grains, deformed grains and serious lattice distortion. By correlating the temperature histories and grain characteristics at different positions of the interface, the formation mechanism of diverse grains was revealed, referring to crystallization from liquid, recrystallization from the solid and plastic deformation. The recrystallization at the interface was closely related to the material properties, and the significant variations in dislocation density and plastic strain values at the interface, as well as the thermal softening of the material, could be explained by different degrees of dynamic recovery and recrystallization.

Structural, spectroscopic and morphology studies on green synthesized ZnO nanoparticles

Zinc oxide nanoparticles (ZnO NPs) were synthesised using Tabernaemontana divaricata flower extract (TFE) in different weight percentages by facile, eco-friendly and cost-effective green synthesis method. Formation and structure of the ZnO NPs were studied by powder XRD, FT−IR, Raman and TEM studies. The crystals formed are of hexagonal wurtzite structure with biological functional groups attached. Average crystallite size of the ZnO NPs (17.5−23.3 nm) was obtained from the analysis of powder XRD data which increased with increase of TFE amount while the estimated values of dislocation density and micro-strain exhibited an opposite behaviour. The optical (direct and indirect) energy band gap values estimated using UV–vis DRS spectral data decreased with increasing amount of TFE. The photoluminescence spectra for the ZnO NPs exhibited multiple peaks spread over the visible region with one peak in the NIR region indicating the existence of various defect levels of Zn and O. Position of these defect levels within the band gap was assigned which is significantly modulated by TFE. TFE amount-dependent peak shift and/or peak broadening were observed in the Raman spectra of the ZnO NPs which were correlated with the growing disorder in the crystals induced by the extract molecules. FESEM study showed the agglomerated NPs with quasi-spherical morphology. Particle size of the ZnO NPs was estimated from FESEM images. EDX study indicated that increased presence of TFE in ZnO decreased the oxygen content in the synthesised material. HRTEM study revealed the agglomeration of nanoparticles with single crystalline nature. Present study convincingly established that flower extract used for the green synthesis efficiently modified the structure and optical property, defect levels and morphology of the potentially useful ZnO nanoparticles.

Fabrication of praseodymium-doped ceria (PDC) films by slurry spin-coating technique and its structural, morphological and optical properties

The current study is on the fabrication of PDC films prepared by slurry spin-coating technique for photoluminescence activity. At lower spin rates (1000 rpm), thicker and uniform PDC films were obtained. The structural evolution of the sintered PDC films on a dense alumina substrate was studied using Grazing Incidence X-ray diffraction (GIXRD) and Raman Spectroscopy. Crystallite size, microstrain, and dislocation density values remain almost the same with the increase in the coating cycles. The A568/A463 ratio for 3, 5, and 10 coating cycles are 0.52, 0.49, and 0.61, respectively. Surface roughness studies of PDC films using a 3D Noncontact Profilometer. The mean surface roughness values are 12.55, 13.74, and 22.25 μm for the 3rd,5th, and 10th coating cycles, respectively. Microstructure observation by Field Emission Scanning Electron Microscope (FE-SEM). The average thickness of the films for the 3rd, 5th, and 10th coating cycles are 50.93, 41.64, and 109.95 μm, respectively. The PDC films obtained on a dense alumina substrate were porous. FE-SEM micrographs showed a particle aggregation of several irregular and smaller grains, indicating the sintering activity of PDC films. Optical properties were studied using ultraviolet-visible (UV–Vis) absorption spectra and photoluminescence spectra (PLS). The band gap values slightly increased with the increase in the coating cycles. A decrease in PL intensity with an increase in the coating cycle is related to higher oxygen vacancy concentration. PDC films fabricated by the slurry spin-coating technique can be successfully used for optoelectronic applications.

Investigation of the microstructure, hardness and electrical conductivity properties of Fe/Graphene compacts

ABSTRACT The effects of graphene nanoplatelets added to pure Fe powders at different rates on microstructure, hardness and electrical conductivity were investigated. Prepared mixed powders were compressed at 700 MPa pressure and sintered at 1250°C. Densities of samples were measured Archimedes technique. Scanning electron microscope was used for microstructure investigations. The hardness was measured according to ASTM E384. Phase types, average crystallite size and dislocation density calculations in sintered samples were made. Electrical resistance measurements were made with the four-point probe measurement technique. Powder mixtures containing ≤5 wt-% graphene nanoplatelets were sintered into compact samples. The smallest grain size, highest dislocation density, highest hardness and electrical conductivity values were obtained in samples containing 2 wt-% of graphene nanoplatelets.

High temperature annealing on vertical p-n junction p-NiO/n-β-Ga2O3 nanowire arrays for high performance UV photodetection

The authors of this article reported the effects of annealing on performance of GLAD synthesized vertical p-NiO/n-β-Ga2O3 heterostructure (HS) nanowire (NW) arrays based UV photodetector (PD). The authors further investigated the structural, optical and electrical properties at various annealing temperatures (200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C) including as deposited sample to find the best sample for UV PD application. The XRD analysis showed improved crystallinity and least dislocation density and micro strain values for 800 °C sample. However, the sample degrades beyond 800 °C owing to crystallographic defects that are formed at higher annealed temperatures. Furthermore, the photoluminescence analysis showed that the defect levels decreased at 800 °C annealed temperature which was also analogous to the XPS analysis. The FE-SEM analysis also showed the impact of high temperature annealing (800 °C) with increased in nanowire diameter and length. The surface roughness was also found to be smoother for 800 °C sample from TEM analysis. Moreover, the fabricated 800 °C annealed vertical p-NiO/n-β-Ga2O3 axial NW arrays based UV PD showed the largest responsivity (Rλ) of 940 A/W as compared to all the samples. Also, the 800 °C annealed UV PD exhibited fast response speed along with rise time and fall times of 0.32 s and 0.49 s respectively. The superior performance of 800 °C sample was ascribed to the large grain size, defect reduction and improvement of interference quality.

Efficient photo-adsorptive eradication of endocrine disrupting pesticides by chitosan co- decorated metal oxide bio-nanocomposite.

Extensive consumption, toxicity and bioaccumulation of malathion (MLT) and lindane (γ-HCH) pesticides collectively attract the world's attention. Herein, the nanocomposite of chitosan wrapped NiO@ZnO was synthesized by a green methodology usingAzadirachta indicaleaves extract. Structural and morphological analysis of chitosan-NiO@ZnO showed hollow sphere-flake shaped image adsorbed on a solid chitosan surface with a large surface area of 73 m2g-1. A decrease in values of lattice strain, dislocation density and crystallite size described the imperfection in crystal geometry and new peaks in FT-IR spectra at 698cm-1 and 448cm-1 of Ni-N and Zn-N, which respectively confirm the coupling. Chitosan-NiO@ZnO and individual nanoparticles (NiO and ZnO) were well-characterized and utilized for degradation MLT and γ-HCH under direct sunlight and dark conditions. The highest degradation of pesticides (above 94%) resulted with 2mg L-1 and 10mg L-1 of MLT (π-π) and γ-HCH, respectively with a 20mg catalyst dose, and pH of ~ 7 under daylight exposure (5h). Chitosan-NiO@ZnO substantially suppressed the half-life of the targeted pesticides (MLT: 0.48h; HCH 0.51h) and demonstrated the first-order kinetics with a high adsorption capacity, Xm (MLT: 14.5mgg-1 and γ-HCH 20.7mgg-1), which also confirmed the strong binding with the pesticides, followed by their conversion into safer and smaller metabolites. The charge separation mechanism was elucidated by UV reflectance and photoluminescence data. Hydroxyl radicals were most frequently responsible for the degradation of pesticides as confirmed by scavenger analysis. The synthesized green-nano photocatalyst showed high reusability (up to 10th cycles), sensitivity and stability within the degradation process, presumably making it suitable for industrial applications.

Optical and Morphological Properties of Cu2FeSnS4 Chalcogenide Films

P-type Cu2FeSnS4 (CFTS) and Cu2ZnSnS4 (CZTS) quaternary chalcogenide films have been grown by the method of spin coating on glass substrates relate to 30 and 40 sccm sulfur flux. Physical properties of obtained samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and ultraviolet visible spectroscopy (UV-Vis) to see the effect of deposition parameters on the thin film. The crystal parameters including crystal size, dislocation density and strain value of the samples were changed related to the deposition parameters. XRD results indicated an improvement of the crystalline quality of quaternary chalcogenide CFTS with a maximum crystal size of about 50 nm for (112) peak orientation. SEM images illustrated that the particle size was changed with an increase in the flux of sulfur, which was confirmed with both XRD and AFM images. It was seen that the absorption and energy band gap value of the samples changed the effect of sulfur flux and CZTS film for 40 sccm exhibited more strong absorption all samples in the UV-Vis region. The band gap values of the samples were calculated 1.51, 1.53, 1.82 and 1.91 eV for CZTS (30 sccm), CZTS (40 sccm), CFTS (30 sccm) and CFTS (40 sccm) films annealed H2S gas, respectively.