The operating characteristics of a commercial monocrystalline and amorphous Si‐solar cell for outdoor and indoor applications with and without the use of the water flow lens (WFL) system are explored and reported. The cells are tested in indoor conditions with halogen and tungsten lamps, and additionally, in outdoor sun radiation. Changes in the spectra, investigation of the influence of higher and lower lighting, and indirect cooling of the solar cell are possibilities in the application of the used WFL system. After achieving the highest level of development and improvement for the Si‐solar cell, as well as approaching theoretical maximum efficiency, it is obvious that efficiency gains can be made by better understanding additional light effects. Measurements made on monocrystalline Si‐solar cells revealed that in the “focal point position” where intensity increases (above standard testing conditions [STC]), independently of indoor or outdoor lighting, huge improvements in I SC and V OC were observed. It was found that the ratios of the short‐circuit current ( I SC ) and the input light energy ( P input ) are 5.2 and 24.8 for artificial light and 4.9 and 17.6 for outdoor light, without and with the use of the WFL system, respectively. The same trend after applying the WFL system was observed for the amorphous Si cell, except those oscillations were more pronounced at lower light intensities (far lower than STC), as expected. The ratios of I SC and P input are in the range of 5.1–5.3 and 10.5–26.5 without and with the use of the WFL system.

Direct application of heavy metals as antibacterial agents can cause skin irritations and discoloration of the tissue and it can result in short-term applicability. One of the ways to solve these problems is to immobilize these agents on bentonite. Treatment of textile materials with such activated bentonite for use in various branches of industry has attracted the attention of many researchers in recent years. The objective of the present study was to develop a potential use of Cu- and Zn-modified bentonites as antibacterial finishing agents for two textile materials, non-woven textile (NT) and knitted fabric (PL). The bentonite samples were characterized using ED-XRF (energy dispersive X-ray fluorescence spectrometry), XRPD (X-ray powder diffraction), SEM (scanning electron microscopy), FTIR (Fourier-transform infrared spectroscopy), and BET (N 2 adsorption-desorption) analyses. SiO 2 and Al 2 O 3 oxides were the main components of all bentonite samples indicated by ED-XRF analysis, while the XRPD analysis confirmed that the natural bentonite (NB) consisted of montmorillonite (Mnt) as the dominant mineral (peaks at 6.94, 19.94, 35.09, and 54.09°2θ) and small amounts of quartz and calcite. A reduction in the basal plane spacing, d 001 , of Mnt occurred in Cu/Zn-B1, Cu/Zn-B3, and CuB, while in Cu/Zn-B2 and ZnB the basal spacing increased. Also, the size and form of particles and porosity changed, which was confirmed by the BET analysis. Modified bentonite samples experienced a reduction in the specific surface area and total pore volume, as well as movement of the middle mesopore diameter toward the larger diameters. The Zn-modified bentonite demonstrated a greater antibacterial effect on Escherichia coli , Pseudomonas aeruginosa , Staphylococcus aureus, and Bacillus cereus than Cu- and Na-modified bentonite samples with a MIC (minimum inhibitory concentration) of 0.94 mg/mL, while among Cu/Zn bentonite samples, Cu/Zn-B2 had the strongest antibacterial effect (MIC 0.47 mg/mL). Cu/Zn-B2 was integrated on NT and PL using a screen printing method and showed good antibacterial activity. The printed NT showed better activity than printed PL, and increasing the concentration of applied Cu/Zn-B2 also increased the antibacterial properties.

This study presents the 51 mixtures of ceramic clays characterized by using XRF, XRD, granulometry, and dilatometry analyses. After firing in a 1000-1250 degrees C range, water absorption (WA) according to EN standards by boiling in water, under vacuum, and by 24h soaking is determined. The results indicated that there was a high and statistically significant correlation between the standard methods, but the testing under vacuum gave the highest saturation of the samples fired at 1200 degrees C and 1250 degrees C. It is determined that these illitic-kaolinitic clays can be used to produce floor ceramic tiles belonging to the BIIa group (water absorption between 3% and 6%). The study also aimed to reveal which method of WA determination is suitable to read the sintering interval from the gresification diagrams, which is compared to the beginning of sintering as read from dilatometry curves. (C) 2020 SECV. Published by Elsevier Espana, S.L.U.

This paper reports a detailed study of crystal structure and dielectric properties of ruthenium-substituted calcium-copper titanates (CaCu3Ti4−xRuxO12, CCTRO). A series of three samples with different stoichiometry was prepared: CaCu3Ti4−xRuxO12, x = 0, 1 and 4, abbreviated as CCTO, CCT3RO and CCRO, respectively. A detailed structural analysis of CCTRO samples was done by the Rietveld refinement of XRPD data. The results show that, regardless of whether Ti4+ or Ru4+ ions are placed in B crystallographic position in AA’3B4O12 (CaCu3Ti4−xRuxO12) unit cell, the crystal structure remains cubic with Im3¯ symmetry. Slight increases in the unit cell parameters, cell volume and interatomic distances indicate that Ru4+ ions with larger ionic radii (0.62 Å) than Ti4+ (0.605 Å) are incorporated in the CaCu3Ti4−xRuxO12 crystal lattice. The structural investigations were confirmed using TEM, HRTEM and ADF/STEM analyses, including EDXS elemental mapping. The effect of Ru atoms share in CaCu3Ti4−xRuxO12 samples on their electrical properties was determined by impedance and dielectric measurements. Results of dielectric measurements indicate that one atom of ruthenium per CaCu3Ti4−xRuxO12 unit cell transforms dielectric CCTO into conductive CCT3RO while preserving cubic crystal structure. Our findings about CCTO and CCT3RO ceramics promote them as ideal tandem to overcome the problem of stress on dielectric-electrode interfaces in capacitors.

Layered VOPO4·2H2O is synthesized by the sonochemical method. An X-ray powder diffraction is used to examine the crystal structure, while scanning electron microscopy is used to reveal the morphology of the powder. The crystal structure refinement is performed in the P4/nmmZ space group. The electrochemical intercalation of several cations (Na+, Mg2+, Ca2+, and Al3+) in saturated nitrate aqueous solutions is investigated. The most notable reversible activity is found for the cycling in aluminium nitrate aqueous solution in the voltage range from −0.1 to 0.8 V vs. SCE. During the preparation of the electrode, it is observed that the structure is prone to changes that have not been recorded in the literature so far. Namely, the use of conventional binder PVDF in NMP solution deteriorates the structure and lowers the powder’s crystallinity, while the use of Nafion solution causes the rearrangement of the atoms in a new crystal form that can be described in the monoclinic P21/c space group. Consequently, these structural changes affect electrochemical performances. The observed differences in electrochemical performances are a result of structural rearrangements.

Dense calcium phosphate-based ceramics were fabricated to be used as targets for pulsed laser deposition (PLD). Nanostructured cobalt-substituted hydroxyapatite (Co:HAP) was used as a starting powder. To vary phase composition and microstructure of targets, two sintering approaches were applied, conventional (CS) and two-step sintering (TSS). The obtained results show that in both cases biphasic calcium phosphate (BCP) ceramics (targets) were prepared, with slightly different HAP-to-beta-TCP amount ratio and a significantly different microstructure. While the CS method yielded fully dense ceramics with an average grain size of 1.3 mu m, the ceramics prepared by TSS had a density of 98.5%, with a predominant grain size below 100 nm. (Ca + Co)P coatings were prepared by PLD of (Ca + Co)P targets. The temperature of the Ti substrate was adjusted to be 25 and 500 ?. The results show that the phase composition of (Ca + Co)P coatings depended on the phase composition of targets as well as on the temperature of the Ti substrate. The coating prepared at 25 ? using CS target consisted of three calcium phosphate phases, HAP, beta-TCP and alpha-TCP; when the TSS target was used, the coating was biphasic, containing HAP and beta-TCP. When the substrate was heated to 500 ?, regardless of whether the CS or the TSS target was used, the deposited coatings were composed of HAP and alpha-TCP. Due to different phase compositions, the (Ca + Co)P coatings deposited at 25 ? showed an improved hardness compared to those deposited at 500 ?. The obtained results confirmed that the phase composition, morphology and mechanical properties of 0.3 mu m thick (Ca + Co)P coatings on a Ti substrate can be tailored by employing (Ca + Co)P targets with different microstructures, and also by varying the temperature of the Ti substrate during deposition experiments.

As an extension of our previous studies of multi-component semiconductors doped with magnetic impurities, this paper gives a comprehensive insight into electronic and local structure of crystalline semiconductors Cd(0.98)Co(0.02)Se( )and Cd0.98Co0.02Se0.9Te0.1, and Cd0.98Co0.02Se0.9Te0.1. Detailed characterization of Co and Se local environment and overall influence of Co and S(Te) (co)doping on the host crystal structure has been obtained by X-ray absorption fine structure (XAFS) technique and electronic structure calculations. Important structural information on bond lengths and disorder parameters were extracted from the extended region of the absorption spectra, while the relationships between electronic and local structures were determined from the characteristic features appearing in the near-edge spectral region. The influence of various structural defects on local electronic properties, charge transfer and atomic interactions has been studied by theoretical modeling of XAFS spectra and calculations of local density of electronic states. The obtained findings offer possible means for improvement and extension of the practical application of CdSe-based materials by adjusting the details of their electronic structure.

Pyrolytic tire (PT) chars were first produced from waste car tires (WCT) through carbonization process at 800 degrees C, for different retention times. Then, best PT-char sample by its physicochemical properties (WCT 800(1 h)) was further tested for its ability to adsorb Rhodamine B (RhB) dye from aqueous solutions. Structural characterization of synthesized material showed existence of graphene-based material, with average pore diameter of 22.8 nm and specific surface area of 55.8 m2.g- 1. Obtained carbon material meets specifications of commercial carbon black (CB). The yield of 33.6% of CB recovered has been achieved. Under the optimal conditions, 99.57% of RhB was removed. Adsorption of RhB obeys pseudo second-order model and Langmuir isotherm model. DFT (the density functional theory) was revealed that effective bonding of RhB onto WCT 800 originates from pi-electron interactions with aromatic moieties and chemical (or at least the electrostatic) interactions, between positive nitrogen and electron-rich surface groups.

In this work we deposited nickel thin films by Glancing Angle Deposition at two different angles (65 degrees and 85 degrees) onto glass substrates. The structure of the films, thicknesses between 50 and 200 nm, was studied by scanning electron microscopy, atomic force microscopy and X-ray diffraction, while the chemical properties were analyzed using X-ray photoelectron spectroscopy. According to the obtained results it can be seen that the deposition angle has influence on porosity, crystallinity and surface roughness. Optical properties were investigated by spectroscopic ellipsometry and electrical properties were measured by four point probe. Spectroscopic ellipsometry revealed that the refractive index and extinction coefficient varied with thickness and deposition angle, which can be correlated with changes in microstructure and porosity of Ni films. The observed variations in resistivity could be attributed to the changes in the width of the columns, as well as to the amount of oxide present in the samples.

The polyanion cathodes for Li-ion batteries, namely LiFePO4, Li2FeP2O7 and Li2FeSiO4, were synthesized by very short high-temperature treatment (approximately several minutes) and subsequent quenching. Methylcellulose—a polymer with thermally driven water solubility—was used as the medium in which the precursor solutions were dispersed prior to high temperature treatment. The methylcellulose pyrolytically decomposes to carbon, thus producing the polyanion material/carbon composites of LiFePO4/C, Li2FeP2O7/C and Li2FeSiO4/C. The obtained powders have reduced crystallinity and significant microstructural characteristics: low crystallite size and notable microstrain. They exhibit stable electrochemical performances in both aqueous and organic electrolyte. The broadening of existing peaks in cyclic voltammetry and/or the emergence of new broad peaks was attributed to the presence of the amorphous phase in the samples. In galvanostatic charge–discharge tests, the materials provided high capacities at low current densities, while the highest rate performance was demonstrated by olivine-phosphate when compared to the other two materials.

Electrochemical and structural properties of LiV2O5 cathode were investigated. Obtained by solid state reaction at high temperature the material crystallized as gamma polymorph phase, gamma-LiV2O5. The gamma structure provides two crystallographic sites to accommodate lithium ions, Li1 and Li2 position. Lithium insertion at these two sites occurs at two respective voltages versus lithium metal: -3.6 V (Li1) and -2.4 V (Li2). Intercalation at Li1 position is reversible in both organic and aqueous electrolyte and provides stable cycling performance at the high voltage. On the contrary, sluggish insertion/removal of Li+ at Li2 sites causes unstable performance and significant storage capacity fade at lower voltages. Lithium diffusion 3d landscape was determined by bond valence calculations applied on the gamma-LiV2O5 phase, as well as on the metastable phases of gamma '-V2O5 and zeta-Li2V2O5 that exist at high and low voltages respectively. The model was proposed based on inactivity of Li2 position of the metastable zeta-Li2V2O5 phase which provides explanation for the observed storage capacity loss at low voltages.

In this study, four low molecular weight (LMW) excipients, tryptophan (TRY), phenylalanine (PHE), lysine (LYS) and saccharin (SAC) were evaluated as co-formers to generate co-amorphous systems (CAMS) by ball milling with carvedilol (CRV). Mixtures of CRV and LMW excipient in 1:0.5, 1:1 and 1:2 drug:excipient molar ratios were ball milled and analysed by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), Fourier transform (FT-IR) infrared spectroscopy and dissolution testing. CAMS were formed by milling of a mixture of CRV with TRY in 1:2 M ratio and SAC in 1:1 M ratio, while amorphization of only CRV was achieved in other mixtures with SAC. In other samples containing TRY and PHE, milling resulted in partial amorphization, while LYS was the least suitable excipient for the amorphization of CRV. Unexpectedly, the highest supersaturation of CRV was achieved from samples containing CRV and LYS in 1:1 and 1:2 M ratios, despite the absence of a significant reduction in CRV crystallinity upon milling of these samples. Increase of hydrophobic surface area caused by milling of samples with TRY and PHE and agglomeration during dissolution testing of samples containing SAC are likely causes of poor dissolution performance of mixtures containing fully or partially amorphous CRV.

LiAlH4 is a promising material for hydrogen storage, having the theoretical gravimetric density of 10.6 wt% H-2. In order to decrease the temperature where hydrogen is released, we investigated the catalytic influence of Fe2O3 on LiAlH4 dehydrogenation, as a model case for understanding the effects transition oxide additives have in the catalysis process. Quick mechanochemical synthesis of LiAlH4 thorn 5 wt% Fe2O3 led to the significant decrease of the hydrogen desorption temperature, and desorption of over 7 wt%H-2 in the temperature range 143-154 degrees C. Density functional theory (DFT)-based calculations with Tran-Blaha modified Becke-Johnson functional (TBmBJ) address the electronic structure of LiAlH4 and Li3AlH6. Fe-57 Mossbauer study shows the change in the oxidational state of iron during hydrogen desorption, while the H-1 NMR study reveals the presence of paramagnetic species that affect relaxation. The electron transfer from hydrides is discussed as the proposed mechanism of destabilization of LiAlH4 + 5 wt% Fe2O3. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Though a simple daily observation , evaporation of drops is still poorly understood due to the complex nature that involves hydrodynamic effects in the bulk fluids and transport phenomena at the liquid-vapor interface. This paper reports on the evaporation of single component droplets (water , ethanol , acetone , and glycerol) levitated in a single-axis non-resonant levitator. It was observed that the acetone and ethanol evaporated faster than water , although the acetone is the most volatile. The estimated lifetime of acetone is less than 5 min , which is much shorter as compared to 56 min for ethanol or about 90 min for water droplets. On the other hand , glycerol showed no tendency to evaporate. With increasing the evaporation time , the ratio of large and small semi-axis decreases and tends to 1 corresponding to changes in drops shape from oblate ellipsoid to a sphere. Based on the classical D-2-law, the surface regression rates have been estimated.

In this paper two methods of preparation of yttrium orthovanadate nanopowders were presented: Solid State Reaction (top – down approach) and Solution Combustion Synthesis (bottom – up approach). For starting structural characterization, X – Ray Powder Diffraction (XPRD) and Field Emission Scanning Electron Microscopy (FESEM) were used. We report the change in reflection spectra in europium doped YVO4 nanopowders with comparison to its bulk analog. In UV–Vis reflection spectra we consider the change in values of band gap in these structures, after resizing it from bulk to nanomaterial. In Far – Infrared (FIR) reflection spectra, we registered the existence of Surface Optical Phonon (SOP) and different multi – phonon processes which alter the reflection spectra of bulk YVO4. The influence of Eu ions is reflected through multi – phonon processes that occur and are connected with energy transfer from YVO4 lattice to Eu ions. All IR spectra were modeled using classical oscillator model with Drude part added which takes into account the free carrier contribution. Since our samples are distinctively inhomogeneous materials, we use Effective Medium theory in Maxwell Garnett approximation to model its effective dieletric function.

Fayalite Fe2SiO4 is synthesized by the solid-state reaction without ball milling. The obtained powder is further structurally and electrochemically examined. Field emission scanning electron microscopy (FESEM) showed that microsized powder is obtained. X-ray powder diffraction (XRD) pattern is used for both phase identification and crystal structure Rietveld refinement. The structure is refined in the orthorhombic Pbnm space group. Mössbauer spectroscopy revealed traces of Fe3+ impurity. The bond valence mapping method is applied for the first time on Fe2SiO4 framework. It shows isolated, non-connected isosurfaces of constant E(Li), which further supports the assumptions of the conversion reactions. Electrochemical performances are investigated through galvanostatic cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). Ex-situ XRD and Fourier transform infrared spectroscopy (FTIR) analyses are combined to monitor phase change after galvanostatic cycling and to reveal the working mechanism during electrochemical lithiation.

In this paper, we investigated YF3: Yb/Er, YF3: Yb/Tm, and YF3: Yb/Ho solid solutions prepared by reaction of an appropriate amount of oxides with ammonium difluoride (NH4HF2) as a fluorinating agent. These samples were characterized by Xray diffraction (XRD), magnetic measurements, and up-conversion (UC) photoluminescence spectra. The results show that all samples are single-phase and crystallize in an orthorhombic crystal structure of the ?-YF3 structure type. Above 100 K, the measured molar magnetic susceptibility was fitted by the Curie-Weiss law and the average effective magnetic moments for the observed samples were obtained. All the samples showed pure paramagnetic behavior. When doped with lanthanide elements (Yb/Er, Yb/Tm, Yb/Ho), YF3 solid solutions can emit characteristic green, red, blue, and near IR light under the excitation of a 980 nm laser diode.

Hexagonal ZnIn2S4 is synthesized by simple and low-cost hydrothermal route. TEM images revealed formation of nanosheets. The estimated band-gap energy of synthesized sample is in the visible spectral region and has a value of about 2.25 eV. Photocatalytic properties of synthesized sample are probed in photocatalytic degradation of three selected dyes different in nature and structure, Rhodamine B (RhB), Methylene blue (MB) and Methyl orange (MO), under the illumination with simulated Solar light. Obtained results revealed that photocatalytic degradation of RhB and MO is mainly result of synergic effect of photogenerated holes and oxygen, while primary effect in ZnIn2S4/MB system is bleaching of the dye, but no photodegradation was observed.

This study investigated the combined influence of pH adjusting agent type (hydrochloric, acetic or lactic acid) and initial pH value (3.6, 4.6, and 5.6) on formation of biocompatible chitosan/xanthan polyelectrolyte complexes (PECs), their characteristics in solid state and influence on in vitro ibuprofen release kinetics. Conductivity measurements and rheological characterization revealed generally higher extent of ionic interactions in PEC dispersions comprising acetic acid and at pH 3.6. Acid type and pH affected significantly the yield and particle size (100-250 mu m) of the dried PECs. Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (PXRD) analysis of the solid PECs confirmed exclusively physical (ionic, hydrogen bonds) interactions between chitosan and xanthan gum. PECs prepared with acetic acid at pH 4.6 and 5.6 had enhanced rehydration ability in phosphate buffer pH 7.2, and at PEC-to-drug mass ratio up to 1:2, enabled extended ibuprofen release from hard capsules during 10 h. (C) 2020 Elsevier B.V. All rights reserved.