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The relationship between local structure and visible-light activated photocatalytic effect of simulated domestic waste slag glass–ceramics (R-NaWSFe) was investigated. The largest pseudo-first-order rate constant of 9.75 × 10−3 min−1 was estimated for methylene blue decomposition test under the visible-light irradiation using R-NaWSFe with additional 30 mass% of Fe2O3 heat-treated at 900 °C for 100 min. The reason for the high photoactivity of this sample was mainly due to nanoparticles of CaFe2O4 and α-Fe2O3 confirmed by the Mössbauer spectrum measured at 77 K. It is concluded that the nanoparticles of magnetic components in silica are essential for exhibiting visible-light activated catalytic effect. [ABSTRACT FROM AUTHOR]

The composition and structure of the white pigments used in the encrustation paste on prehistoric ceramics is analysed and described. Encrustations, pigments and their use were studied chronologically, starting with their first appearance during the early Kostolac culture (3500-3000 bc, Copper Age), their very extensive use in the Vučedol culture (3000-2500 bc, Copper Age) and their final disappearance with the Pannonian complex of Encrusted Pottery (2000-1500 bc, Bronze Age). Most of the Kostolac and Vučedol culture material is from the Vučedol and Vinkovci Hotel localities. The Pannonian culture material is from the Grabrovac (Ðakovo) locality. The encrustations were analysed by deep field optical microscopy, polarization microscopy, scanning electron microscopy with EDS, and XRD. Our investigation showed that from the very beginning to the end of the use of the encrustation technique in this area and by these cultures, the composition of the white paste was quite unique. The base material is produced by burning and powdering of deer antler. Crushed freshwater clam shells ( Unio sp.) were a common addition to the phosphate paste. [ABSTRACT FROM AUTHOR]

Mechanochemical modification of previously synthesized LaFeO3 perovskite-type oxide by a high-energy ball milling was investigated to introduce Fe4+ ions or transform some Fe3+ into Fe4+ in LaFeO3. X-ray absorption fine structure studies revealed that the formation of Fe4+ ions into LaFeO3 perovskite has been achieved at first time by ball milling at room temperature without any additives or replacement of La3+ ions by some divalent cations. The structural model of Fe4+ containing LaFeO3 could be described as with a modified perovskite having equal amounts of La and Fe vacancies, which is supported by a good correlation between the results of Fe K-edge XANES spectra and O2-TPD. The synthesis of Fe4+-containing LaFeO3 perovskite by ball milling was able to produce the O2 adsorption capacity of nonsubstituted perovskite-type oxide. [ABSTRACT FROM AUTHOR]

The effect of HCl additions on the formation of precipitates by hydrolysis of FeCl3 solutions at 90 °C has been investigated using X-ray powder diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). In the precipitation systems with 0.1 M FeCl3, the concentration of HCl varied between 0.005 and 0.1 M, whereas the maximum time of hydrolysis was 35 days. At the beginning of the hydrolytic process, the formation of precipitate was strongly suppressed with an increase in HCl concentration. β-FeOOH was found as a single phase in the precipitates for the concentration 0.1 M FeCl3+0.01 M HCl after 1 and 3 days of hydrolysis. For the concentrations [HCl]≥0.05 M, the precipitates also contained a small amount of α-FeOOH. FT-IR spectroscopy was proved to be a useful technique in the detection of α-FeOOH. After 35 days of hydrolytic process, α-Fe2O3 was found as the end product of precipitation, whereas some precipitates also contained small amounts or traces of α-FeOOH. The size and shape of the particles strongly depended on the HCl concentration. Forced hydrolysis of 0.01 M FeCl3+0.005 M HCl solution for 35 days yielded small and uniform α-Fe2O3 particles (∼0.08 μm). [Copyright &y& Elsevier]

Phase composition, size and shape of iron oxide particles produced by forced hydrolysis of Fe3+ ions depended on the concentrations of FeCl3 and HCl, and on the presence of 0.005 M quinine hydrogen sulphate (QHS). After 7 days of forced hydrolysis, α-Fe2O3 was produced from the 0.01 M FeCl3 solution, the mixture of β-FeOOH and α-Fe2O3 was produced from 0.02 M FeCl3 solution, whereas β-FeOOH was produced from the 0.1 M FeCl3 solution. Forced hydrolysis of the 0.1 M FeCl3+0.1 M HCl solution yielded α-Fe2O3. In the presence of 0.005 M QHS, the formation of β-FeOOH and α-Fe2O3 was partially or completely suppressed in dependence on the conditions of forced hydrolysis of Fe3+ ions. Specific shapes of β-FeOOH particles (cigar-type, X-, Y-, and star-shapes) were not obtained in the presence of 0.005 M QHS. The bundles of β-FeOOH needles with irregular ends were obtained instead. Also, in the presence of 0.005 M QHS, the formation of α-FeOOH is favoured. The preferential adsorption of sulphate groups and a possible influence of quinine group at the very beginning of FeCl3 hydrolysis were suggested as responsible for the effects observed. [Copyright &y& Elsevier]

Debye temperatures of α -Sn x Fe 1- x OOH nanoparticles ( x = 0, 0.05, 0.10, 0.15 and 0.20, abbreviated as Sn100 x NPs) prepared by hydrothermal reaction were estimated with 57 Fe- and 119 Sn-Mössbauer spectra measured by varying the temperature from 20 to 300 K. Electrical properties were studied by solid-state impedance spectroscopy (SS-IS). Together, the charge-discharge capacity of Li- and Na-ion batteries containing Sn100 x NPs as a cathode were evaluated. 57 Fe-Mössbauer spectra of Sn10, Sn15, and Sn20 measured at 300 K showed only one doublet due to the superparamagnetic doublet, while the doublet decomposed into a sextet due to goethite at the temperature below 50 K for Sn 10, 200 K for Sn15, and 100 K for Sn20. These results suggest that Sn10, Sn15 and Sn20 had smaller particles than Sn0. On the other hand, 20 K 119 Sn-Mössbauer spectra of Sn15 were composed of a paramagnetic doublet with an isomer shift ( δ ) of 0.24 mm s -1 and quadrupole splitting (∆) of 3.52 mm s -1 . These values were larger than those of Sn10 ( δ : 0.08 mm s -1 , ∆: 0.00 mm s -1 ) and Sn20 ( δ : 0.10 mm s -1 , ∆: 0.00 mm s -1 ), suggesting that the Sn IV -O chemical bond is shorter and the distortion of octahedral SnO 6 is larger in Sn15 than in Sn10 and Sn20 due to the increase in the covalency and polarization of the Sn IV -O chemical bond. Debye temperatures determined from 57 Fe-Mössbauer spectra measured at the low temperature were 210 K, 228 K, and 250 K for Sn10, Sn15, and Sn20, while that of α -Fe 2 O 3 was 324 K. Similarly, the Debye temperature of 199, 251, and 269 K for Sn10, Sn15, and Sn20 were estimated from the temperature-dependent 119 Sn-Mössbauer spectra, which were significantly smaller than that of BaSnO 3 (=658 K) and SnO 2 (=382 K). These results suggest that Fe and Sn are a weakly bound lattice in goethite NPs with low crystallinity. Modification of NPs and addition of Sn has a positive effect, resulting in an increase in DC conductivity of almost 5 orders of magnitude, from a σ DC value of 9.37 × 10 -7 (Ω cm) -1 for pure goethite Sn (Sn0) up to DC plateau for samples containing 0.15 and 0.20 Sn (Sn15 and Sn20) with a DC value of ~4 × 10 -7 (Ω cm) -1 @423 K. This non-linear conductivity pattern and levelling at a higher Sn content suggests that structural modifications have a notable impact on electron transport, which is primarily governed by the thermally activated via three-dimensional hopping of small polarons (SPH). Measurements of SIB performance, including the Sn100 x cathode under a current density of 50 mA g -1 , showed initial capacities of 81 and 85 mAh g -1 for Sn0 and Sn15, which were larger than the others. The large initial capacities were measured at a current density of 5 mA g -1 found at 170 and 182 mAh g -1 for Sn15 and Sn20, respectively. It is concluded that tin-goethite NPs are an excellent material for a secondary battery cathode and that Sn15 is the best cathode among the studied Sn100 x NPs.

The present study investigates the relationship between the local structure, photocatalytic ability, and cathode performances in sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs) using Ni-substituted goethite nanoparticles (Ni x Fe 1-x OOH NPs) with a range of 'x' values from 0 to 0.5. The structural characterization was performed applying various techniques, including X-ray diffractometry (XRD); thermogravimetry differential thermal analysis (TG-DTA); Fourier transform infrared spectroscopy (FT-IR); X-ray absorption spectroscopy (XANES/EXAFS), both measured at room temperature (RT); 57 Fe Mössbauer spectroscopy recorded at RT and low temperatures (LT) from 20 K to 300 K; Brunauer-Emmett-Teller surface area measurement (BET), and diffuse reflectance spectroscopy (DRS). In addition, the electrical properties of Ni x Fe 1-x OOH NPs were evaluated by solid-state impedance spectroscopy (SS-IS). XRD showed the presence of goethite as the only crystalline phase in prepared samples with x ≤ 0.20, and goethite and α-Ni(OH) 2 in the samples with x > 0.20. The sample with x = 0.10 (Ni10) showed the highest photo-Fenton ability with a first-order rate constant value ( k ) of 15.8 × 10 -3 min -1 . The 57 Fe Mössbauer spectrum of Ni0, measured at RT, displayed a sextet corresponding to goethite, with an isomer shift ( δ ) of 0.36 mm s -1 and a hyperfine magnetic distribution ( B hf ) of 32.95 T. Moreover, the DC conductivity decreased from 5.52 × 10 -10 to 5.30 × 10 -12 (Ω cm) -1 with 'x' increasing from 0.10 to 0.50. Ni20 showed the highest initial discharge capacity of 223 mAh g -1 , attributed to its largest specific surface area of 174.0 m 2 g -1 . In conclusion, Ni x Fe 1-x OOH NPs can be effectively utilized as visible-light-activated catalysts and active cathode materials in secondary batteries.

In this work, we investigated the morphological and electrochemical properties of gallium/bismuth mixed oxide. The bismuth concentration was varied from 0 to 100%. The correct ratio was determined with inductively coupled plasma-optical emission spectroscopy (ICP-OES), while surface characteristics were determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurement. Electrochemical characteristics were studied using electrochemical impedance spectroscopy (EIS) in the Fe 2+/3+ couple. The obtained materials were tested for adrenaline detection. After square wave voltammetry (SWV) optimization, the best electrode showed a wide linear working range from 7 to 100 µM at pH 6 of the Britton-Robinson buffer solution (BRBS) supporting electrolyte. The limit of detection (LOD) for the proposed method was calculated as 1.9 µM, with a limit of quantification (LOQ) of 5.8 µM. The excellent selectivity of the proposed method, with good repeatability and reproducibility, strongly suggests the possible application of the procedure for the determination of adrenaline in artificially prepared real samples. The practical applicability with good recovery values indicates that the morphology of the materials is closely connected with other parameters, which further suggests that the developed approach can offer a low-cost, rapid, selective, and sensitive method for adrenaline monitoring., (© 2023. Springer-Verlag GmbH Germany, part of Springer Nature.)

There is an increasing need to develop new polymer composites with improved properties compared to conventional pure polymer materials. This work aims to develop composites of low-density polyethylene (LDPE) and iron oxide hematite particles. For this purpose, different types of hematite particles with well-defined shapes and narrow size distributions were synthesized: HC2 sample with pseudocubic hematite particles of an average diameter of 1020 nm, HE1 sample with ellipsoidal hematite particles of an average diameter of 533 nm, and HS1 sample with spherical hematite particles of an average diameter of 168 nm. The mass fractions of hematite in the composites were 0.25%, 0.5%, and 1%. Prepared LDPE/hematite composites were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The mechanical and barrier properties were also studied. The obtained results showed that all prepared composites have improved properties compared to the pure LDPE, especially the composites with pseudocubic hematite particles of well-defined shapes. The results of this study indicate that LDPE/hematite composites can be promising materials for a wide range of applications, especially as packaging materials where improved thermal and mechanical properties as well as resistance to ultraviolet (UV) irradiation are required.

Morphine (MORPH) is natural alkaloid and mainly used as a pain reliever. Its monitoring in human body fluids is crucial for modern medicine. In this paper, we have developed an electrochemical sensor for submicromolar detection of MORPH. The sensor is based on modified carbon paste electrode (CPE) by investigating the Fe x W 1-x O 4 ratio in iron tungstate (FeWO 4 ), as well as the ratio of this material in CPE. For the first time, the effect of the iron-tungsten ratio in terms of achieving the best possible electrochemical characteristics for the detection of an important molecule for humans was examined. Morphological and electrochemical characteristics of materials were studied. The best results were obtained using Fe 1 W 3 and 7.5% of modifier in CPE. For MORPH detection, square wave voltammetry (SWV) was optimized. Under the optimized conditions, Fe 1 W 3 @CPE resulted in limit of detection (LOD) of the method of 0.58 µM and limit of quantification (LOQ) of 1.94 µM. The linear operating range between 5 and 85 µM of MORPH in the Britton-Robinson buffer solution (BRBS) at pH 8 as supporting electrolyte was obtained. The Fe 1 W 3 @CPE sensor resulted in good selectivity and excellent repeatability with relative standard deviation (RSD) and was applied in real-world samples of human urine. Application for direct MORPH detection, without tedious sample pretreatment procedures, suggests that developed electrochemical sensor has appeared to be a suitable competitor for efficient, precise, and accurate monitoring of the MORPH in biological fluids.

The solid-state ion-selective electrodes presented here are based on the FePO 4 :Ag 2 S:polytetrafluoroethylene (PTFE) = 1:1:2 with an addition of (0.25-1)% microwave-synthesized hematite (α-Fe 2 O 3 ), magnetite (Fe 3 O 4 ), boehmite [γ-AlO(OH)], and alumina (Al 2 O 3 ) nanoparticles (NPs) in order to establish ideal membrane composition for iron(III) cations determination. Synthesized NPs are characterized with Fourier-Transform Infrared (FTIR) spectroscopy, Powder X-Ray Diffraction (PXRD), and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). The iron oxides NPs, more specifically, magnetite and hematite, showed a more positive effect on the sensing properties than boehmite and alumina NPs. The hematite NPs had the most significant effect on the linear range for the determination of ferric cations. The membrane containing 0.25% hematite NPs showed a slope of -19.75 mV per decade in the linear range from 1.2∙10 -6 to 10 -2 mol L -1 , with a correlation factor of 0.9925. The recoveries for the determination of ferric cations in standard solutions were 99.4, 106.7, 93.6, and 101.1% for different concentrations.

High-energy ball-milling in an oxidative atmosphere caused gradual transition of pure zincite into zinc ferrite due to the oxidation of steel contamination. The rate of contamination increased dramatically (>3×) in an inert atmosphere due to the abrasion of milling tools by the steel chips coming from it.