ABSTRACT The formation of solid silicon spikes (noses) during needle‐eye float zone (FZ) silicon growth may, depending on their characteristics, be a cause of process failure. We employ modeling to characterize the stability of noses in various electromagnetic and thermal environments and present a theory of nose formation. The main factors determining nose stability are found to be the magnetic field strength, the induction frequency, the temperature of the environment, and the shape of the nose. The theory shows good agreement with experimental observations and enables a quantitative distinction between stable and disruptive growth regimes.
ABSTRACT The aim of this work is to use the root of Caulokaempferia secunda (Wall.) K. Larsen to biosynthesize cobalt oxide (Co 3 O 4 ) nanoparticles (NPs). The evaluation of the synthesized NPs was carried out by using various standard techniques. The characterization results established the successful synthesis, structural reliability, functional properties, and nanoscale size of the nanoparticles. The synthesized Co 3 O 4 NPs were employed to assess free radical scavenging activity using 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) and their antimicrobial potential against Gram‐positive and Gram‐negative bacteria. The electrochemical investigation of the Co 3 O 4 NPs was performed using cyclic voltammetry. The nanoparticles exhibited admirable antibacterial activity against the four tested microorganisms. The DPPH free radical scavenging activity of Co 3 O 4 NPs ranged from 21.62% to 72.29%, indicating a notable capacity to neutralize free radicals and demonstrating significant antioxidant activity. Furthermore, cyclic voltammetry analyses reveal that the synthesized Co 3 O 4 displays hysteresis in its cathodic and anodic peak potentials, which ranged from −0.1 to +0.1 V. The findings of this study suggest that green‐synthesized Co 3 O 4 NPs containing C. secunda root extract could be utilized in biomedicine, supercapacitors, and as a substitute for biological and electrochemical applications. The nanoparticles that are synthesized exhibit promising antibacterial, antioxidant, and electrochemical properties, highlighting their potential.
ABSTRACT Organic ammonium halides, which are obtained by neutralizing organic amines with hydrogen halides, exhibit several properties and functions based on their diverse hydrogen bond networks. Here we report 2‐(2‐hydroxyethyl)anilinium chloride as a novel organic ammonium halide and describe its reversible hydration/dehydration behavior under mild conditions. Single‐crystal X‐ray diffraction analysis shows that this halide crystalizes into two different lamellar‐type crystals, anhydrate and monohydrate, composed of hydrophobic phenyl and hydrophilic hydrogen bonded layers. Powder X‐ray diffraction, thermogravimetric, and gas adsorption analyses indicate that the anhydrate crystals adsorb water vapor by incorporating water molecules into their hydrophilic layers under atmospheric humidity, and the monohydrate crystals readily desorb water by mild heating at approximately 50°C for several minutes. Notably, these hydration and dehydration processes are reversible with crystal‐to‐crystal transformation. Therefore, 2‐(2‐hydroxyethyl)anilinium chloride can be utilized as an excellent water vapor adsorber, opening up the potential for organic ammonium halides, particularly anilinium halide frameworks, as a functional crystalline material.
ABSTRACT In this work, we have studied the effects of thermal and electrical processing on crystallization, electrical, and electromechanical behavior of polymeric Poly (L‐lactic acid) (PLLA) films deposited on top of medical‐grade 316L stainless steel using the rapid thermal annealing (RTA) method. Stepwise annealing at 180°C and 120°C produced well‐defined crystalline spherulitic structures under an air atmosphere, while a vacuum atmosphere produced amorphous films, confirming the key role of nitrogen and oxygen elements in the promotion of the primary nucleation process. The secondary nucleation process was further modulated by corona‐poling discharge at a DC bias voltage of –5 kV, which induced dipole alignment as evidenced by Maltese cross patterns and enhanced birefringence. To achieve nanoscale control, Atomic Force Microscopy‐based local poling with electric fields of 3 GV/m was used to generate predefined polarization patterns. Kelvin Probe Force Microscopy and Piezoresponse Force Microscopy analyses confirmed reversible dipole switching, while Electrostatic Force Microscopy measurements revealed stable surface charges confined to crystalline regions, indicating that the observed charges are electromechanical and not electrostatic in origin. These results demonstrate a multiscale strategy for controlling crystallization and polarization in thin PLLA films. The combined RTA and electric‐field‐assisted methods enable precise tuning of piezoelectric properties in semicrystalline regions of PLLA for advanced sensing and bioelectronic applications.
ABSTRACT The present investigation establishes a relationship between lattice distortion, cation distribution, and magnetic properties, and proves that Mn 2 + /La 3 + co‐substitution is an efficient route to tailor the structural and magnetic properties of cobalt ferrites. Co 1 − 2x Mn x La x Fe 2 O 4 (x = 0.00 to 0.10) nanoparticles were synthesized via the sol–gel auto‐combustion route to investigate the effect of Mn 2 + and La 3 + co‐substitution on the structural, morphological, and magnetic properties of cobalt ferrite. XRD patterns reveal a single cubic spinel phase for all samples. FTIR spectra show the typical metal‐oxygen bands for both tetrahedral and octahedral sites, confirming the spinel structure and exhibiting small band shifts due to cation substitution and lattice distortions. FESEM images reveal a nanoscale particle size with an agglomerated structure, and grain refinement at lower doping concentrations. Room temperature VSM analysis confirms ferrimagnetic behavior for all samples. The saturation magnetization increases from 82.63 to 87.34 emu/g at x = 0.02 due to enhanced magnetic contribution from Mn 2 + at the B‐site, followed by a decrease at higher Mn/La doping levels due to magnetic dilution from non‐magnetic La 3 + ions and spin canting effects. Coercivity exhibits a non‐monotonic variation, reaching a maximum at x = 0.02, consistent with increased magneto‐crystalline anisotropy and strain‐induced stress anisotropy.
ABSTRACT Czochralski (Cz) crystal growth remains the dominant technique for producing Monocrystalline Silicon (Mono‐Si) for photovoltaic and semiconductor applications. However, the performance and yield of Cz‐grown silicon ingots are strongly influenced by oxygen incorporation during crystal growth. This review critically examines both modeling and experimental studies addressing oxygen impurity behaviors in Cz‐grown Mono‐Si, with particular emphasis on achieving lower oxygen concentration and improved spatial uniformity within the crystal and melt. The influence of key growth parameters including pulling rate, crystal and crucible rotation, melt convection, argon flow rate and pressure, crystal diameter and length, heater configuration, and applied magnetic fields—on oxygen incorporation and transport is systematically discussed. Advances in global and Multiphysics simulations used to predict oxygen transport, chemical reactions, and deposition during crystal growth are also reviewed. Furthermore, optimized rotation conditions and crucible geometries aimed at improving crystal quality are summarized. Experimental characterization techniques such as Fourier‐transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), photoluminescence (PL), and related methods are reviewed to correlate oxygen‐related defects with growth conditions. This review provides a comprehensive overview of oxygen‐induced defects and mitigation strategies in Cz‐grown silicon, offering insights for the development of device‐quality silicon ingots for photovoltaic and semiconductor technologies.
ABSTRACT In this research, three synthesis conditions of green‐emitting colloidal CsPbBr 3 nanocrystals obtained by LARP are discussed. Room temperature (A‐RT), low temperature air atmosphere (A‐LT), and a stationary‐state nitrogen flow injection at room temperature (N‐RT), are described. The samples were analyzed through XRD, SEM, UV–Vis, PL, and FT‐IR. A crystalline cubic phase and by products mixture were identified; an average size of 15.5 to 11 nm was calculated, being the smallest one obtained at low temperature. From SEM, it is observed that morphology is affected by the ambient conditions (i.e., A‐RT and N‐RT samples); the particle size decreases, showing rod‐like‐shaped nanoparticles. Additionally, by the UV–Vis spectra, three contributions are localized, at 510, 519, and 522 nm; this could be associated with the cubic phase/byproducts. In correlation to PL, it was possible to identify the main emission peak of each sample, which was located at 511, 519, and 522 nm for A‐LT, N‐RT, and A‐RT, respectively, noticing a redshift probably due to the size dependence. The TRPL and PLQY are measured to analyze which mechanisms are responsible for each sample emission. Finally, to identify the presence of any organic byproduct compound, the FT‐IR characterization was done.
ABSTRACT SnO 2 ‐based gas sensors are widely studied for hazardous gas detection due to their high sensitivity and stability; however, their practical application is often restricted by high operating temperatures. In this work, SnO 2 thin films with different precursor molarities (0.05, 0.1, 0.25, and 0.5 m ) were prepared using the sol–gel spin coating technique and annealed at 500°C for 1 h in ambient air to investigate their room‐temperature NH 3 sensing performance. XRD analysis confirmed the formation of polycrystalline tetragonal rutile SnO 2 thin films, while FE‐SEM studies revealed denser morphology and increased thickness with increasing molarity. Gas sensing measurements performed at NH 3 concentrations of 100–500 ppm demonstrated that the 0.5 m SnO 2 thin film exhibited the highest sensing response of 49.2 at 500 ppm, along with rapid response and recovery behavior at room temperature (30°C). The enhanced sensing performance is attributed to increased surface activity and adsorption sites in the high‐molarity films. The results demonstrate that precursor concentration strongly influences the structure–property relationship and sensing behavior of SnO 2 thin films, highlighting their potential for low‐cost and energy‐efficient room‐temperature ammonia sensing applications.
ABSTRACT Kidney stone disease (nephrolithiasis) is a recurrent urological disorder in which calcium oxalate (CaOx) is the predominant crystalline component. This study investigated the effects of anethole, isoeugenol, silibinin, and potassium citrate on CaOx crystallization kinetics under varying supersaturation conditions. Induction time analysis demonstrated that all tested compounds delayed crystal nucleation at lower supersaturation ratios, with potassium citrate increasing induction time from ∼460 s in the control to ∼650 s at SRs 0.72. Surface energy and nucleation rate analyses further revealed supersaturation‐dependent modulation of crystallization kinetics, particularly in the presence of silibinin. FESEM analysis showed reduced crystal aggregation and altered crystal morphology in treated groups, while XRD and FTIR confirmed calcium oxalate monohydrate (COM) as the predominant crystalline phase. Zeta potential measurements demonstrated enhanced negative surface charge at high supersaturation, particularly for anethole (−38.8 ± 0.75 mV) and potassium citrate (−28.5 ± 0.75 mV), suggesting improved colloidal stability and reduced aggregation tendency. Collectively, the findings indicate that these phytochemicals modulate CaOx nucleation, growth, and aggregation through supersaturation‐dependent interfacial interactions. The integrated kinetic, structural, and morphological analyses presented here provide further insight into phytochemical‐mediated regulation of calcium oxalate crystallization, although additional in vivo and clinical studies are required to establish therapeutic relevance.
ABSTRACT Stearic acid is a non‐toxic, biocompatible, and biodegradable compound, making it a highly promising candidate for the development of hydrophobic surfaces and coatings. Electrospray crystallization, a pivotal technique in materials science and surface engineering, has not been directly utilized with stearic acid as a hydrophobic precursor material. Therefore, in this research, Response surface methodology was employed to optimize the stearic acid coating by the electrospray crystallization process by investigating key operational parameters such as solid content, applied voltage, collector distance, and feed flow rate. These parameters were found to have a significant impact on the resultant contact angle, a critical measure of hydrophobicity in coatings. Scanning electron microscopy characterizations conducted at key experimental stages further revealed how these parameters influenced crystal size and morphology. This work provides fundamental knowledge into how electrospray operational parameters influence crystal properties, enabling the rational design of hydrophobic surfaces. These findings suggest potential applicability in areas such as self‐cleaning materials, anti‐fouling coatings, membranes, and microfluidic devices, although further studies involving dynamic wettability and durability are required to validate these applications.
ABSTRACT To improve the quality and growth efficiency of AlN films prepared by Metal Nitride Vapor Phase Epitaxy(MNVPE), AlN was deposited at different temperature stages on sapphire substrates treated with N 2 and Al vapor, followed by the epitaxial growth of AlN films. The morphology, stress, and other properties of the AlN films were analyzed. It was found that after treating the sapphire substrate with Al vapor, the AlN film grown under 1300°C for 20 min exhibited the best quality, the full width at half maximum (FWHM) of the (0002) and X‐ray rocking curves was 436 arcsec and the surface roughness (RMS) reached 3.64 nm. Analysis revealed that the Al vapor etches the sapphire substrate and promotes grain coalescence and grain boundary reduction during the deposition of the intermediate‐temperature AlN layer, providing driving forces for dislocation bending and annihilation in subsequent AlN growth. This work explores the effects of different precursor gases on substrate pretreatment and the mechanism by which the deposited layers influence film quality, offering significant insights for the preparation of high‐quality AlN films.
ABSTRACT This study investigated the effects of iron, zinc, and calcium ions (Fe 2 + , Zn 2 + , and Ca 2 + , respectively) on the solvent‐mediated polymorphic transformation of glycine and subsequent crystal properties. The transformation from β‐ into α‐glycine was monitored in real time using ultrasonic velocity measurements and revealed that these metal ions delayed the transformation in a concentration‐dependent manner, with Fe 2 + showing the strongest delay. x‐ray diffraction and microscopy analyses confirmed the complete transformation into α‐glycine, with significant morphology changes induced by the additives. Scanning electron microscopy and image‐based analyses showed that Fe 2 + led to compact, agglomerated crystals with irregular shapes, while Zn 2 + and Ca 2 + caused moderate thickening of the rod‐like α‐glycine crystals. Zeta potential measurements demonstrated metal ion adsorption on crystal surfaces, reducing surface charge and promoting agglomeration, particularly in the Fe 2 + system. Filtration tests revealed a sharp increase in specific cake resistance with Fe 2 + , while Zn 2 + and Ca 2 + improved filtration performance. Thermogravimetric analysis and in‐situ Fourier transform infrared spectroscopy analyses confirmed a consistent two‐step thermal degradation pattern across all samples, with minor variations in decomposition temperatures and evolved gas profiles.
ABSTRACT Laser powder bed fusion (LPBF)‐fabricated Ti6A4V alloys often suffer from insufficient comprehensive mechanical properties and pronounced anisotropy. In contrast, the introduction of rare earth elements offers a promising approach to performance optimization. In this study, Ti6Al4V‐ x Y 2 O 3 alloys were produced by incorporating different mass fractions of Y 2 O 3 particles into Ti6Al4V powder, followed by LPBF processing, and their microstructural characteristics and mechanical properties were systematically investigated. The results show that the addition of 0.2 wt.% Y 2 O 3 induces significant grain refinement, reducing the β grain size from 92.3 to 60.4 µm and the α′ martensitic lath size from 10.4 to 8.6 µm. At this composition, the alloy achieves an optimal combination of mechanical properties, with the yield strength increased from 1126 to 1208 MPa and the ultimate tensile strength from 1259 to 1331 MPa. This study provides new insights and experimental evidence for tailoring the microstructure and enhancing the mechanical performance of LPBF‐processed titanium alloys via rare‐earth oxide modification.
In this study, zinc tungstate nanoparticles (ZW NPS) were synthesized by a simple, rapid microwave synthesis method. The as-synthesized ZW NPS were characterized by XRD, XPS, SEM, and TEM analysis. The results show the presence of a nanorod morphology, and the average crystalline size was found to be similar to 32 nm. The ZW NPs were used as electrocatalysts for the electrooxidation of the methanol reaction (MOR) in an alkaline medium. The ZW NPS exhibited excellent MOR activity and stability over 4000 s.
Single crystals of pure and 0.5 mol% Cu2 + substituted lithium sulphate monohydrate (LSMH) were grown by slow evaporation. The novelty of this work lies in establishing a defect-assisted conduction model correlating Cu2 + substitution, lithium vacancy formation, impedance relaxation, surface morphology, nonlinear optical efficiency, and laser damage resistance. Structural substitution is inferred from ionic size compatibility and systematic electrical response modification. Complex impedance spectroscopy (323-353 K, 20 Hz-2 MHz) reveals bulk-dominated conduction exhibiting non-Debye relaxation. The data were fitted using an equivalent circuit model consisting of Rb-CPE elements, and fitting parameters are reported. AC conductivity follows Jonscher's power law, confirming thermally activated hopping via vacancy defects. A defect chemistry model based on Cu2 substitution at Li+ sites is proposed to explain conductivity changes. AFM reveals increased roughness upon doping. Second harmonic generation (SHG) was confirmed using the Kurtz-Perry method, and laser damage threshold (LDT) values (similar to 3 GW/cm2) indicate high optical stability. The combined electrical-defect-optical correlation establishes Cu2 + substituted LSMH as a promising multifunctional photonic material.
ABSTRACT The chemical transformations of CeO 2 and Ru/CeO 2 catalysts under oxidative treatment (i.e., typical conditions of oxidation reactions on metal/oxide catalysts) were investigated using in situ Raman spectroscopy, and complemented by near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS). The main attention was focused on the Raman study of the effect of Ru loadinag degree on the structure of CeO 2 support in Ru/CeO 2 catalysts undergoing oxidative treatment. The advances and limitations of Raman spectroscopy for studying the chemical state of Ru/CeO 2 catalysts were systematically investigated and discussed, demonstrating its high potential to monitoring the physicochemical state of ceria support in the Ru/CeO 2 system. The limited applicability of Raman spectroscopy for monitoring the Ru species in Ru/CeO 2 catalyst was also demonstrated.
This study investigates the structural, morphological, and optical modifications induced by cerium (Ce) doping in zinc oxide (ZnO) nanostructures synthesized by a controlled hydrothermal method. X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-Visible spectroscopy (UV-vis), and photoluminescence (PL) spectroscopy were used for characterization. XRD confirmed that all samples retained the hexagonal wurtzite structure after Ce incorporation. The crystallite size varied between 32.6 and 49.5 nm, showing a non-monotonic dependence on cerium (Ce) concentration. SEM and TEM revealed a gradual morphological transformation from interlinked hexagonal particles to spherical structures with increasing Ce content. Optical analysis showed slight bandgap variation from 3.209 to 3.226 eV, indicating modification of the ZnO electronic structure. Photoluminescence spectra exhibited enhanced visible emission in the 650-700 nm region with increasing Ce concentration, attributed to defect-mediated radiative recombination associated with Ce-3(+)/Ce-4(+) states. These findings demonstrate that controlled Ce doping effectively tailors the structural and optical properties of Zinc oxide (ZnO), 16 through defect engineering. The resulting Ce-doped ZnO nanostructures show potential for applications requiring tunable charge transport and light-management properties in optoelectronic materials.
This study investigates the effects of grain size and temperature on the tensile properties and deformation mechanisms of a body-centered cubic nanocrystalline Fe-Mn alloy using molecular dynamics simulations. Results indicate that Young's modulus increases with grain size, while the dominant deformation mechanism transitions from grain boundary (GB) migration to dislocation glide and stacking fault formation. The alloy exhibits Hall-Petch and inverse Hall-Petch behaviors with a critical grain size of similar to 16.21 nm, which triggers large-scale intragranular twinning. Elevated temperatures reduce peak stress and Young's modulus by widening GBs and suppressing dislocation formation in favor of GB-mediated deformation. Furthermore, macroscopic tensile experiments on Q345R steel validate the simulated macro-mechanical responses and grain-refinement strengthening within the Hall-Petch regime. These findings provide a theoretical basis for the strengthening-toughening mechanisms and temperature-dependent design of nanocrystalline alloys.
ABSTRACT Lead halide perovskite has attracted extensive attention in the field of photoelectric conversion and detection due to its excellent photoelectric properties. However, the toxicity of lead and environmental pollution will affect the practical application. By substituting Cu + for Pb 2+ and MA + for Cs + , a new organic–inorganic hybrid copper (I) halide MACu 2 I 3 single crystal with 1D structure was successfully prepared by slow evaporation of solvent. The results show that the crystal belongs to the monoclinic system (P2 1 /m), and the MACu 2 I 3 single crystal is a direct band gap material with a direct band gap of 2.09 eV. The photoluminescence spectrum shows that the excitation peak of the MACu 2 I 3 crystal is 330 nm, and the emission peaks are 415 and 610 nm, respectively, with the corresponding fluorescence decay times being 0.21 and 329 ns, indicating that the MACu 2 I 3 single crystal exhibits ultrafast luminescence decay behavior. Therefore, this work highlights the potential of the MACu 2 I 3 single crystal in the field of ultrafast optics.
ABSTRACT The crystal structures of metacetamol form I, hemihydrate, and acetone hemisolvate were investigated using single‐crystal x‐ray diffraction, complemented by Hirshfeld surface, fingerprint, energy framework, and void analyses. Comparative evaluation reveals that structural differences among these forms primarily stem from variations in hydrogen‐bonding networks and packing efficiency. Form I exhibits the most compact arrangement, stabilized by O–H···O and N–H···O hydrogen bonds in conjunction with π–π stacking, resulting in a dense and efficient packing motif. In contrast, the hemihydrate highlights the role of lattice water, which establishes an extended hydrogen‐bonding framework that disrupts aromatic stacking and enlarges void volume, thereby reducing packing density. The acetone hemisolvate displays the most fragmented and voluminous voids, stabilized predominantly by N–H···O = C and O–H···O = C interactions with solvent molecules. Fingerprint plots confirm the prevalence of H···H contacts, with notable contributions from O···H/H···O interactions. Quantitative void analysis demonstrates a progressive decline in packing efficiency across the series: form I (10.194%) < hemihydrate (12.793%) < acetone hemisolvate (12.983%). Energy framework analysis indicates variations in electrostatic and dispersion interaction contributions across the crystal forms, reflecting differences in intermolecular interaction networks. These results underscore the impact of solvation on intermolecular interactions and crystal packing, offering valuable insights for pharmaceutical solid‐state design.
