Solid State Phenomena Vol. 394

Abstract: Lanthanum vanadate (LaVO₄) exhibits photoluminescence and energy conversion properties under light or electromagnetic irradiation, and has been applied in phosphors, scintillators, and photocatalysis, making it one of the smart photo-functional materials. Under the requirements of a low-carbon society and environmental conditions, low energy consumption material processes have become the focus of research. Lanthanum acetate [La(CH₃COO)₃] and ammonium metavanadate (NH₄VO₃) were used as precursor solutions. Under a fixed ultrasonic frequency of 35 kHz, lanthanum vanadate (LaVO₄) nanoparticles were synthesized by varying the precursor solution temperature (26 °C and 50 °C), reaction time (30 min and 50 min), and intermittent irradiation conditions (5 s on / 55 s off). The crystalline structure of the powders was identified using X-ray diffraction (XRD), while the crystal morphology and particle size distribution were examined by transmission electron microscopy (TEM). The results show that this process can synthesize lanthanum vanadate (LaVO₄) nanopowders under low-temperature and energy efficiency conditions, with rod-like morphologies and grain sizes of approximately 20–100 nm. This study also found that obtaining particles with a uniform and fine grain size is more difficult without the addition of coordination compounds and surfactants.

Abstract: This study reports the synthesis and comprehensive characterization of V₂ZnC-PVA saturable absorbers (SAs) fabricated via solution-casting methods. The thin films were examined for their structural, chemical, and optical properties to evaluate their suitability for ultrafast photonic applications. Surface morphology and thickness were assessed using field emission scanning electron microscopy (FESEM) and 3D laser scanning microscopy, while elemental composition and crystallinity were confirmed through energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Raman spectral analysis, through its molecular vibration signatures, verified both the preservation of the MAX-phase structure and the overall stability of the films. Optical characterization revealed distinct behaviours: linear absorption measurements confirmed high transparency with adjustable absorption profiles, whereas nonlinear experiments conducted with a twin-balanced detector demonstrated pronounced saturable absorption, achieving modulation depths above 12 % and saturation intensities in the order of kW·cm^-2. Together, these findings demonstrate that V₂ZnC-PVA saturable absorbers are suitable for ultrafast photonics, especially in passive Q-switching and mode-locking, because of their strong nonlinear response, uniform morphology, and superior resistance to optical damage with a high damage threshold.

Abstract: The nanofabrication of long-range ordered metal nanostructures has garnered significant research attention in the advancement of plasmonic-assisted sensor development. In this study, we report efficient nanofabrication of silver arrays on Teflon (Tef/Ag) for fabricating a surface-enhanced Raman spectroscopy (SERS) sensor for detecting multiple pollutants. The number of laser pulses was systematically varied from 200 to 10000 to study its impact on the morphological features of Ag nanoarrays. Atomic Force Microscopy (AFM) and UV-visible spectroscopy were employed to study the morphological and optical characteristics, respectively. The physical properties were then correlated to their corresponding sensing activities. The number of laser pulses was optimized to achieve the highest SERS sensing efficiency. The sensor fabricated at 5000 laser pulses exhibited the highest SERS enhancement, attributed to the formation of a highly dense metal nano-island formation (Fig. 1a). Compared to silicon and quartz, Teflon provided the best substrate for achieving the highest SERS enhancement. An enhancement factor of 3.1 × 10⁷ has been estimated for Teflon/Ag sensor, which showed superior efficiency of the fabricated sensor. The reproducibility of the sensor showed relative standard deviation values of 9.1%. The sensor was further validated for the detection of various environmental pollutants, demonstrating its potential as a flexible, reusable and efficient platform for environmental monitoring.

Abstract: The facile, fast and cost effective atmospheric-pressure cold plasma-assisted aerosol deposition (APCP-AAD) method is investigated to synthesize dual-band electrochromic (DB-EC) chloro-nitro-organo-tungsten oxide (WO_xC_yN_z1Cl_z2) films with independently selective visible (VIS) and near-infrared (NIR) light. DB-EC WO_xC_yN_z1Cl_z2 film can be switched by three changed EC modes including bright, cool and dark states by adjusting various electrical potentials to correspond the favorites and comfort of construction residents and reduce energy consumption for lighting and heat management. High optical modulation in VIS light ΔT_{bright to dark, 600 nm} up to 67.4% and in NIR light ΔT_{bright to dark, 1,000 nm} up to 72.4%, and fast response times in coloring duration up to 5.0 s and in bleaching duration up to 1.2 s.

Abstract: This study investigated the absorption spectra of rare earth metal (REM) doped polymer composite material, specifically Europium Aluminum-doped Benzyl Methacrylate (Eu-Al/BzMA), which were ascertained from a 0.56-cm bulk sample. The results revealed the most intense peak at 395 nm induced by the Eu³⁺ ion absorption. Under 350-nm UV light excitation, Eu-Al/BzMA exhibited sharp red emission at 617 nm corresponding to the ⁵D₀→⁷F₂ transition. The absorption cross sections were determined as 5.62 × 10^-22 cm² for the signal and 6.1 × 10^-22 cm² for the pump. Collectively, these results demonstrate that Eu-Al/BzMA is a promising gain medium for highly efficient active devices in visible-range applications.

Abstract: This study explores the incorporation of multilayer Ti₃C₂T_x MXene into a polyacrylate-based photocurable resin for stereolithography (SLA). Composites with 3–10 wt% MXene were fabricated and characterized for microstructure, electrical, mechanical, and dimensional accuracy. SEM and XRD confirmed successful MXene formation with partial agglomeration. Electrical conductivity improved up to 8 wt% loading but declined at 10 wt% due to filler aggregation. Mechanical testing showed reduced strength and stiffness but increased ductility with higher MXene content. Optical microscopy revealed high printing resolution, with ~3% error at the top surfaces and ~13% at the bottom. These results demonstrate the feasibility of SLA-printed MXene composites while highlighting the need for optimized dispersion to balance performance.

Abstract: This study investigates the effect of electrolyte concentration on the crystal structure and electrochemical performance of copper hexacyanoferrate (CuHCF) as an electrode material for aqueous zinc-ion batteries. CuHCF electrodes were tested in ZnCl₂ electrolytes with concentrations ranging from 1.0 to 10.0 mol dm⁻³. Electrochemical analyses—including linear sweep voltammetry and galvanostatic cycling—revealed a strong dependence of capacity and cycling stability on electrolyte concentration. The 1.0 M electrolyte exhibited superior initial capacity, whereas the 10.0 M electrolyte demonstrated enhanced capacity retention during prolonged cycling. X-ray diffraction showed that higher concentrations suppressed Zn-ion substitution in the CuHCF lattice, thereby improving structural stability. These findings suggest that careful tuning of electrolyte concentration is critical for balancing initial performance and long-term durability in CuHCF-based zinc-ion batteries.

Abstract: Copper is a valuable industrial metal, extensively utilized in its pure form due to its excellent electrical and thermal conductivities. It plays a vital role in a wide range of applications, including refrigeration systems, coin and jewelry manufacturing, strain gauges, thermocouples, and more. However, in its ionic form, copper (particularly as Cu²⁺) can be toxic, especially when present in industrial effluents and wastewater streams. Therefore, the effective adsorption of cupric ions (Cu²⁺) is a critical environmental and technological concern addressed in this study. From this work, tissue paper pulp waste, chitosan derived from frozen food industry byproducts, and chitosan-coated pulp waste were developed as modified adsorbents for Cu²⁺ removal from aqueous solutions. Brunauer–Emmett–Teller (BET) surface area analysis revealed that chitosan exhibited the highest porosity, while the chitosan-coated pulp provided a well-balanced structure with enhanced functional properties. Under controlled experimental conditions, all three materials demonstrated significant Cu²⁺ removal efficiency, with the chitosan-coated pulp slightly outperforming the others. These findings highlight the potential of chitosan-coated pulp waste as a low-cost, sustainable, and highly effective adsorbent for the remediation of heavy metal-contaminated wastewater.

Abstract: The proposed work shows a way to synthesize blue ceramic pigments. All pigments are synthesized by the method of solid-phase synthesis. Both pure and waste materials were used as raw materials. The optimal conditions for synthesis are determined. The mixtures were sintered at temperatures of 1350 ^°С and 1400 ^°С with one hour isothermal hold. The high-temperature solid-phase synthesis was carried out in a Nabertherm furnace. The chromophore used to acquire the blue color of the pigments is Co, introduced into the batches as Co₂O₃. The amount of the chromophore is 5%. Finely dispersed pigments with a blue color were obtained, obtained from pure and waste raw materials. In the first series, pure Al₂O₃ and SiO₂, introduced into the batches as amorphous SiO₂.nH₂O, were used as starting raw materials, since it is significantly more reactive than ordinary crystalline quartz. In the second series, Al₂O₃ and ash from oxidized rice husk were used, which contain 94.47% SiO₂. The color characteristics of the pigments obtained in this way were determined - color, brightness, color hue using the CIELab system, which gives a numerical expression of the visual sensation of color. It was shown that the best color characteristics are those of the pigments synthesized from pure raw materials at 1350 ^ºС, with 1 hour of isothermal holding, respectively (a) = -4.1 and (b) = -39.2. The obtained pigments were studied by several methods - SEM, X-ray diffraction, and HSМ. The SEM performed shows that clusters are formed in the pigments synthesized with RHA.