Search Results (134)

A simple and rapid precipitation process was successfully employed to prepare silver phosphate (SP, Ag₃PO₄). Two different phosphate sources: diammonium hydrogen phosphate ((NH₄)₂HPO₄) and dipotassium hydrogen phosphate (K₂HPO₄) were applied separately as the precursor, obtaining ((NH₄)₂HPO₄)⁻ and K₂HPO₄⁻ derived SP powders, named SP-A or SP-P, respectively. Fourier transform infrared (FTIR) spectra pointed out the vibrational characteristics of P–O and O–P–O interactions, confirming the presence of the PO43– functional group for SP. X-ray diffraction (XRD) patterns revealed that the SP crystallized in a cubic crystal structure. Whereas the field emission scanning electron microscope (FESEM) exposed spherical SP particles. The potentially antibacterial activity of SP-A and SP-P against bacterial Bacillus stratosphericus, yeast Meyerozyma guilliermondii, and fungal Phanerodontia chrysosporium was subsequently investigated. All studied microorganisms were recovered and isolated from the aquatic plant during the tissue culture process. The preliminary result of the antimicrobial test revealed that SP-A has higher antimicrobial activity than SP-P. The superior antimicrobial efficiency of SP-A compared to SP-P may be attributed to its purity and crystallite size, which provide a higher surface area and more active sites. In addition, the presence of potassium-related impurities in SP-P could have negatively affected its antimicrobial performance. These findings suggest that SP holds potential as an antimicrobial agent for maintaining sterility in tissue cultures, particularly in aquatic plant systems. The growth of both B. stratosphericus and M. guilliermondii was suppressed effectively at 30 ppm SP-A, whereas 10 ppm of SP-A can suppress P. chrysosporium development. This present work also highlights the potential of SP at very low concentrations (10–30 ppm) for utilization as an effective antimicrobial agent in tissue culture, compared to a commercial antimicrobial agent, viz., acetic acid, at the same concentration. Full article

Tin(II) oxide is a promising material for photocatalytic wastewater treatment. However, the established relationships between particle size, shape, and photocatalytic activity of SnO are contradictory, indicating the influence of other factors. In this work, the effect of the SnO crystallographic texture on its band gap and photocatalytic activity was shown for the first time. The relationship between the methods (microwave and hydrothermal microwave) and synthesis conditions (time, pressure, and chemical composition of the suspension) of polycrystalline tin oxide(II) and the crystallographic texture was studied. The crystallographic texture was estimated by the Harris method using the repeatability factor and the Lotgering coefficient. The formation of crystallites oriented in the growth plane (00l) was facilitated by the carbonate medium of the suspension. In the ammonia medium, crystallites were preferably formed in the plane (h0l). Increasing the time and pressure leads to the recrystallization of SnO. The band gap energy of the SnO increases from 3.0 to 3.6 eV, and the rate of photodestruction of methyl orange decreases with the growth of crystallites in the (00l) plane from 17 to 40%. Full article

This work investigated the structural response and phase transformation dynamics of silica-bearing cherts subjected to high-temperature processing (up to 1400 °C) and prolonged mechanochemical activation. Through a combination of X-ray diffraction (XRD) with Rietveld refinement, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and transmission electron microscopy (HRTEM), we trace the crystallographic pathways of quartz, moganite, tridymite, and cristobalite under controlled thermal and mechanical stress regimes. The experimental results demonstrated that phase behavior is highly dependent on intrinsic properties such as initial phase composition, impurity presence, and crystallinity. Heating at 1400 °C induced irreversible conversion of quartz, moganite, and tridymite into cristobalite. Samples enriched in cristobalite and tridymite exhibited notable increases in crystallinity, whereas quartz-dominant samples showed either stability or a decline in structural order. Rietveld analyses underscored the critical influence of microstrain and crystallite size on thermal resilience and phase persistence. Thermal profiles revealed by DSC and TGA expose overlapping processes including polymorphic transitions, minor phase dehydration, and redox-driven changes, likely associated with trace components. Mechanochemical processing resulted in partial amorphization and the emergence of phases such as opal and feldspar minerals (microcline, albite, anorthite), interpreted as the product of lattice collapse and subsequent reprecipitation. Heat treatment of chert leads to a progressive rearrangement and recrystallization of its silica phases: quartz collapses around 1000 °C before recovering, tridymite emerges as an intermediate phase, and cristobalite shows the greatest crystallite size growth and least deformation at 1400 °C. These phase changes serve as markers of high-temperature exposure, guiding the identification of heat-altered lithic artefacts, reconstructing geological and diagenetic histories, and allowing engineers to adjust the thermal expansion of ceramic materials. Mechanochemical results provide new insights into the physicochemical evolution of metastable silica systems and offer valuable implications for the design and thermal conditioning of silica-based functional materials used in high-temperature ceramics, glasses, and refractory applications. From a geoarchaeological standpoint, the mechanochemically treated material could simulate natural weathering of prehistoric chert tools, providing insights into diagenetic pathways and lithic degradation processes. Full article

This study focused on investigations of FeCo and FeNi nanowires prepared by template-assisted electrodeposition in polycarbonate membranes. Nanowires with a diameter of 100 nm and length of 6 µm were grown at different cathodic potentials and electrolyte compositions. Scanning electron microscopy images revealed densely packed arrays of continuous nanowires with smooth surfaces without visible porosity, regardless of the applied potential. Chemical analysis of nanowires pointed out weak sensitivity of chemical composition on the electrodeposition potential in the case of FeCo nanowires, in contrast to FeNi nanowires, where the increase of the cathodic potential resulted in higher Ni content. X-ray diffraction studies showed polycrystalline structure for all samples indicating B2 phase (Pm-3m) with isotropic growth of FeCo nanowires and FeNi₃ phase with a preferential growth along [111] direction in the case of FeNi nanowires. The peak broadening suggests a fine crystalline structure for both FeCo and FeNi materials with average crystallite sizes below 20 nm. Magnetic studies indicated an easy axis of magnetization parallel to the nanowire axis for all FeCo nanowires and potential-dependent anisotropy for FeNi nanowires. The present studies thus suggested the feasibility of producing segmented nanowires based on FeNi alloys, while poor chemical sensitivity to the applied potential was observed for the FeCo system. Full article

TiO₂ is an abundant material on Earth, essential for the sustainable and cost-effective development of various technologies, with anatase being the most effective polymorph for photocatalytic and photovoltaic applications. Bulk crystalline anatase TiO₂ exhibits a band gap energy E_gA = 3.2 eV, for tetragonal lattice parameters a_A = 0.3785 nm and c_A = 0.9514 nm, but these characteristics vary for amorphous or polycrystalline thin films. Reactive magnetron sputtering has proven suitable for the preparation of TiO₂ coatings on glass fiber substrates, with structural and optical characteristics that change during growth. Below a minimum thickness (t < 0.2 μm), the films have an amorphous nature or extremely small crystallite sizes not observable by X-ray diffraction. Afterwards, compressed quasi-randomly orientated crystallites are detected (volume strain ΔV = −0.02 and stress σ_V = −3.5 GPa for t = 0.2 μm) that evolve into relaxed and preferentially (004) orientated crystallites, reaching the standard anatase values at t ~ 1.4 μm with σ_V = 0.0 GPa. The band gap energy increases with lattice distortion according to the relation ∆E_g (eV) = −6∆V, and a further increase is observed for the thinnest coatings (∆E_g = 0.24 eV for t = 0.05 μm). Full article

In this study, we highlight the use of the alkaline earth metal barium (Ba) for the impregnation of Ag₃PO₄ (AgP). AgP was synthesized via co-precipitation and subsequently impregnated with a Ba²⁺-containing solution, followed by hydrothermal treatment to obtain Ba-AgP. The addition of barium significantly influenced both the crystallinity and crystallite size. Ba impregnation enhanced the crystallinity of AgP and promoted the growth of its crystallites. It was confirmed that Ba²⁺ was homogeneously distributed on the surface of AgP, with only a slight effect on particle shape. Ba-impregnated Ag₃PO₄ (Ba-AgP) exhibited improved photocatalytic activity for the degradation of methyl orange (MO) under visible light compared to bare AgP. The optimal impregnation concentration of Ba²⁺ was determined to be 6%. This enhancement is attributed to the role of Ba²⁺ in facilitating the separation of photogenerated electron–hole pairs, which also contributed to the improved stability of AgP. The active species h⁺, ·OH, and O₂·⁻ were all identified as essential for the MO degradation process, with h⁺ being the most significant contributor. Full article

AlCrN and AlCrSiN coatings were deposited via reactive magnetron sputtering. This study investigates the effects of radio frequency (RF) substrate bias, ranging from 0 V to 200 V, on the chemical composition, microstructure, and mechanical properties of the coatings. All crystalline coatings exhibited a single wurtzite-type hexagonal close-packed (hcp) structure. At a 0 V substrate bias, the AlCrN coating consisted of porous V-shaped columnar crystallites, while the AlCrSiN coating exhibited a porous, fiber-like amorphous structure. As the substrate bias increased, crystal growth was promoted, void density decreased, and the surface morphology transitioned from a textured to a more rounded appearance. Additionally, the preferred orientation shifted toward the (101) direction. However, at excessively high substrate bias, re-nucleation occurred, leading to grain refinement and increased film densification, which in turn caused a further shift in the preferred orientation toward the (002) plane. Due to its multi-element composition and the low solubility of Si in nitrides, AlCrSiN coatings tend to exhibit an amorphous growth tendency during sputtering. As a result, their microstructure is more sensitive to substrate bias. This sensitivity results in the formation of a highly dense structure with an optimal crystallite size at a substrate bias of 100 V, leading to a hardness of 22.6 GPa—surpassing that of the AlCrN coating. Full article

In this study, silver nanoparticles (Ag NPs) were synthesized on the surface of rutile-phase titanium dioxide (R-TiO₂) using a plasma-assisted technique. Comprehensive analyses were conducted to investigate the structural, morphological, optical, and electrical properties of the synthesized nanocomposites. Transmission electron microscopy (TEM) images revealed the uniform decoration of Ag NPs (average size: 29.8 nm) on the R-TiO₂ surface. X-ray diffraction (XRD) confirmed the polycrystalline nature of the samples, with decreased diffraction peak intensity indicating reduced crystallinity due to Ag decoration. The Williamson–Hall analysis showed increased crystallite size and reduced tensile strain, suggesting grain growth and stress relief. Raman spectroscopy revealed quenching and broadening of R-TiO₂ vibrational modes, likely due to increased oxygen vacancies. X-ray photoelectron spectroscopy (XPS) confirmed successful plasma-assisted deposition and the coexistence of Ag⁰ and Ag⁺ states, enhancing surface reactivity. UV-Vis spectroscopy demonstrated enhanced light absorption across the spectral range, attributed to localized surface plasmon resonance (LSPR), and a reduced optical bandgap. Dielectric properties, including dielectric constants, loss factor, and AC conductivity, were evaluated across frequencies (4–8 MHz) and temperatures (20–240 °C). The AC conductivity results indicated correlated barrier hopping (CBH) and overlapping large polaron tunneling (OLPT) as the primary conduction mechanisms. Composition-dependent dielectric behavior was interpreted through the Coulomb blockade effect. These findings suggest the potential of plasma assisted Ag NP-decorated R-TiO₂ nanostructures for photocatalysis, sensor and specific electro electrochemical systems applications. Full article

Plasma-enhanced chemical vapor deposition (PECVD) was used to obtain several graphite nanowall (GNW)-type films at different deposition times on silicon and copper to achieve various thicknesses of carbonic films for the development of electrochemical sensors for the detection of anthracene. The PECVD growth time varied from 15 min to 30 min to 45 min, while scanning electron microscopy (SEM) confirmed the changes in the thickness of the GNW films, revealing a continuous increase in the series. X-ray diffraction (XRD) analysis revealed that the crystallinity of the GNW film samples increased with increasing crystallite size and decreasing dislocation density as the deposition time increased. Electrochemical characterization of the GNW-based electrodes indicated that the electroactive area and heterogeneous electron transfer rate constant were greater for the GNW 45 min film in the carbonic material series. We present the transfer of GNW films on flexible polyethylene substrates for achieving flexible electrochemical sensors for further use in anthracene determination. The flexible GNW-based electrodes were investigated using differential pulse voltammetry (DPV) in the presence of anthracene. The results showed that the highest sensitivity in anthracene detection was provided by the sensor with the GNW film obtained after 45 min of PECVD growth. The optimization of the GNW film thickness for the development of flexible electrochemical sensors on polyethylene substrates represents a successful approach for enhancing the electrochemical performance of carbonic materials. Full article

Due to its unique electronic and optical properties, tungsten disulfide (WS₂) is a promising material for various device applications. However, achieving an efficient and cost-effective method for synthesizing large-area uniform WS₂ is still challenging. In this work, we demonstrate the synthesis of few-layer WS₂ crystallites by NaCl-assisted low-pressure chemical vapor deposition and study the effect of temperature and the carrier gas flow rate on the morphology, structure, and optical properties of the as-grown WS₂ films. We observe transitions between regular triangular to strongly disordered structures with sizes up to 50 µm through temperature and carrier gas flow rate tuning. As-grown samples were characterized by Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The result of this work provides a path toward the optimization of growth conditions for obtaining WS₂ with desired morphologies for various applications. Full article

In this study, Al-Al₄C₃ compounds were manufactured by mechanical milling followed by heat treatment. To analyze the microstructural evolution, the composites were sintered at 550 °C at different sintering times of 2, 4 and 6 h. The mechanical results suggest that dislocation density and crystallite size primarily contribute to hardening before the sintering process, with a minimal contribution from particle dispersion in this condition. The compound exhibited a significant 75% increase in hardness after 2 h of sintering, primarily attributed to the nucleation and growth of Al₄C₃ nanorods. The HRTEM analysis, combined with geometric phase analysis (GPA) at and near the Al-Al₄C₃ interface of the nanorods, revealed strain field distributions primarily associated with partial screw dislocations and the presence of closely spaced dislocation dipoles. These findings are consistent with the microstructural parameters determined from X-ray diffraction pattern analysis using the convolutional multiple whole profile (CMWP) method. This analysis showed that the predominant dislocation character is primarily of the screw type, with the dislocation dipoles being closely correlated. Based on these results, it is suggested that samples with a lower weight percentage of reinforcement and longer sintering times may experience reduced brittleness in Al/Al₄C₃ composites. Strengthening contributions were calculated using the Langford–Cohen and Taylor equations. Full article

Silver nanodendrites (AgNDs) were effectively synthesized utilizing a phytantriol template at ambient temperature without electrodeposition. In comparison to AgNDs, the phytantriol-templated silver nanodendrites (P/AgNDs) exhibited a smoother structure with the well-ordered growth of smaller particles around 51 nm. Moreover, the P/AgNDs exhibited uniform elemental distribution, forming chemical bonds with functional groups, crystallite size around 42 nm, and high transmittance around 95%. These experimental findings indicate that room temperature-based hierarchical P/AgNDs have considerable potential for diverse applications, specifically in sensing. Full article

This article studies the influence of solid-phase (type 1 samples) and melt-quenching (type 2 samples) technological modes of obtaining Na₃Fe₂(PO₄)₃ polycrystals on their structures and ion-conducting properties. α-Na₃Fe₂(PO₄)₃ polycrystals of the 1st type are formed predominantly under an isothermal firing regime, and the synthesis of the 2nd type is carried out under sharp temperature gradient conditions, contributing to the formation of glassy precursors possessing a reactive and deformed structure, in which the crystallization of crystallites occurs faster than in precursors obtained under isothermal firing. The elemental composition of α-Na₃Fe₂(PO₄)₃ type 2 polycrystals is maintained within the normal range despite the sharp non-equilibrium thermodynamic conditions of synthesis. The microstructure of the type 1 Na₃Fe₂(PO₄)₃ polycrystals is dominated by chaotically arranged crystallites of medium (7–10 μm) and large (15–35 μm) sizes, while the polycrystals of type 2 are characterized by the preferential formation of small (3–4 μm) and medium (7–10 μm) crystallites, causing uniaxial deformations in their structure, which contribute to a partial increase in their symmetry. The advantage of type 2 polycrystals is that they have higher density and conductivity and are synthesized faster than type 1 samples by a factor of 4. The article also considers the issues of crystallization in a solid-phase precursor from the classical point of view, i.e., the process of the formation of small solid-phase nuclei in the metastable phase and their growth to large particles due to association with small crystallites using phase transitions. Possible variants and models of crystallite growth in Na₃Fe₂(PO₄)₃ polycrystals, as well as distinctive features of crystallization between two types of samples, are discussed. Full article

This study investigates the influence of synthesis methods and electrode geometry on the physico-chemical properties of 5%Gd-doped SnO₂. Two distinct synthesis routes, co-precipitation and hydrothermal growth, were employed, resulting in powders denoted as SnO₂: Gd 5%-CP and SnO₂: Gd 5%-HT. Morpho-structural and textural analyses reveal a uniform morphology consisting of quasi-spherical nanoparticles with dimensions of ~6 nm and mesoporosity for CP and a non-uniform morphology with larger nanoparticles of ~42 nm, with irregular shapes and macroporosity for the HT sample, respectively. The powders were deposited onto alumina substrates equipped with platinum interdigital electrodes with alternative gaps of 200 μm and 100 μm. The back-side heater allows for variation in the temperature of the layer. Sensing properties assessed under in-field-like atmospheres simulated by a computer-controlled Gas Mixing System reveal higher sensitivity to methane compared to carbon dioxide. Although the sensor signals did not differ quantitatively, they exhibited distinct saturation tendencies with an increasing methane concentration, attributed to the morpho-structure and porosity induced by the synthesis method. Differentiation was achieved by varying the interdigital gap of the electrodes, highlighting different sensor signals and conduction mechanisms, determined by the specific size of the crystallites. Full article

In recent years, inorganic nanoparticles, including calcium hydroxide nanoparticles [Ca Ca(OH)₂ NPs], have attracted significant interest for their ability to impact plant photosynthesis and boost agricultural productivity. In this study, the effects of 15 and 30 mg L⁻¹ oleylamine-coated calcium hydroxide nanoparticles [Ca(OH)₂@OAm NPs] on photosystem II (PSII) photochemistry were investigated on tomato plants at their growth irradiance (GI) (580 μmol photons m⁻² s⁻¹) and at high irradiance (HI) (1000 μmol photons m⁻² s⁻¹). Ca(OH)₂@OAm NPs synthesized via a microwave-assisted method revealed a crystallite size of 25 nm with 34% w/w of oleylamine coater, a hydrodynamic size of 145 nm, and a ζ-potential of 4 mV. Compared with the control plants (sprayed with distilled water), PSII efficiency in tomato plants sprayed with Ca(OH)₂@OAm NPs declined as soon as 90 min after the spray, accompanied by a higher excess excitation energy at PSII. Nevertheless, after 72 h, the effective quantum yield of PSII electron transport (Φ_PSII) in tomato plants sprayed with Ca(OH)₂@OAm NPs enhanced due to both an increase in the fraction of open PSII reaction centers (qp) and to the enhancement in the excitation capture efficiency (Fv’/Fm’) of these centers. However, the decrease at the same time in non-photochemical quenching (NPQ) resulted in an increased generation of reactive oxygen species (ROS). It can be concluded that Ca(OH)₂@OAm NPs, by effectively regulating the non-photochemical quenching (NPQ) mechanism, enhanced the electron transport rate (ETR) and decreased the excess excitation energy in tomato leaves. The delay in the enhancement of PSII photochemistry by the calcium hydroxide NPs was less at the GI than at the HI. The enhancement of PSII function by calcium hydroxide NPs is suggested to be triggered by the NPQ mechanism that intensifies ROS generation, which is considered to be beneficial. Calcium hydroxide nanoparticles, in less than 72 h, activated a ROS regulatory network of light energy partitioning signaling that enhanced PSII function. Therefore, synthesized Ca(OH)₂@OAm NPs could potentially be used as photosynthetic biostimulants to enhance crop yields, pending further testing on other plant species. Full article