The rapid development of novel energy materials has led to a sustained surge in the global demand for fluorine. Fluorite is the primary source of fluorine globally and is increasingly being exploited. The estimated annual production of fluorite worldwide is approximately 8 million tons, with an additional 5 million tons of fluorite tailings. This accumulation not only consumes land resources, but also contributes to dust generation and F⁻ percolation, leading to water and air contamination. This paper comprehensively reviews the utilization methods of fluorite tailings, including the flotation recovery of quartz and fluorite, the preparation of cement mineralizing agents, and the preparation of concrete mineral additives, autoclaved lime sand brick, and glass-ceramics. Furthermore, potential future applications and research directions are proposed, including the comprehensive recovery of valuable minerals, auxiliary cementitious materials preparation, and the functionalization of glass-ceramics. This study can serve as a reference for expediting the utilization of fluorite tailings, promoting the development of tailing-free mines, and establishing sustainable development strategies.

In the context of reducing its carbon emissions, the Chinese steel industry is currently undergoing an intelligent transformation to enhance its profitability and sustainability. The optimization of production planning and scheduling plays a pivotal role in realizing these objectives such as improving production efficiency, saving energy, reducing carbon emissions, and enhancing quality. However, current practices in steel enterprises are largely dependent on experience-driven manual decision approaches supported by information systems, which are inadequate to meet the complex requirements of the industry. This study explores the current situation in production planning and scheduling, analyzes the characteristics and limitations of existing methods, and emphasizes the necessity and trends of intelligent systems. It surveys the current literature on production planning and scheduling in steel enterprises and analyzes the theoretical advancements and practical challenges associated with combinatorial and sequential optimization in this field. A key focus is on the limitations of current models and algorithms in effectively addressing the multi-objective and multiconstraint characteristics of steel production. To overcome these challenges, a novel framework for intelligent production planning and scheduling is proposed. This framework leverages data- and knowledge-driven decision-making and scenario adaptability, enabling the system to respond dynamically to real-time production conditions and market fluctuations. By integrating artificial intelligence and advanced optimization methodologies, the proposed framework improves the efficiency, cost-effectiveness, and environmental sustainability of steel manufacturing.

The rapid advancement of modern electronics has led to a surge in solid electronic waste, which poses significant environmental and health challenges. This review focuses on recent developments in paper-based electronic devices fabricated through low-cost, hand-printing techniques, with particular emphasis on their applications in energy harvesting, storage, and sensing. Unlike conventional plastic-based substrates, cellulose paper offers several advantages, including biodegradability, recyclability, and low fabrication cost. By integrating functional nanomaterials such as two-dimensional chalcogenides, metal oxides, conductive polymers, and carbon-based structures onto paper, researchers have achieved high-performance devices such as broadband photodetectors (responsivity up to 52 mA/W), super-capacitors (energy density ∼15.1 mWh/cm²), and pressure sensors (sensitivity ∼18.42 kPa⁻¹). The hand-printing approach, which eliminates the need for sophisticated equipment and toxic solvents, offers a promising route for scalable, sustainable, and disposable electronics. This review outlines fabrication methods and key performance metrics, and discusses the current challenges and future directions for realizing robust, flexible devices aligned with green technology and the United Nation’s Sustainable Development Goals.

Gas rapid unloading (GRU) is an innovative technology for ore comminution. Increasing the production of fine powder in each ore grinding cycle is vital for scaling up the GRU method to industrial applications. This study utilizes laboratory experiments to demonstrate that moderately reducing the orifice size significantly enhances pulverization and increases fine particle yield. Numerical simulations suggest that smaller orifices improve pulverization by increasing jet speed, reducing pressure drop, and creating a larger pressure difference inside and outside the unloading orifice. The orifice size should be optimized based on feed size to ensure efficient ore discharge. Reducing the unloading orifice size improves GRU grinding efficiency and energy use, offering guidance for the design of ore discharge ports in future industrial-scale equipment.

Utilizing coarse aggregates containing mining waste rock for backfilling addresses the strength requirements and reduces the expenses associated with binder and solid waste treatment. However, this type of material is prone to aggregate segregation, which can lead to uneven deformation and damage to the backfill. We employed an image-segmentation method that incorporated machine learning to analyze the distribution information of the aggregates on the splitting surface of the test blocks. The results revealed a nonlinear relationship between aggregate segregation and variations in solid concentration (SC) and cement/aggregate ratio (C/A). The SC of 81wt%–82wt% and C/A of 10.00wt%–12.50wt% reflect surges in fluid dynamics, friction effects, and shifts in their dominance. A uniaxial compression experiment, supplemented with additional strain gauges and digital image correlation technology, enabled us to analyze the mechanical properties and failure mechanism under the influence of aggregate segregation. It was found that the uniaxial compressive strength, ranging from 1.75 MPa to 12.65 MPa, is linearly related to both the SC and C/A, and exhibits no significant relationship with the degree of segregation in numerical terms. However, the degree of segregation affects the development trend of the elastic modulus to a certain extent, and a standard deviation of the aggregate area ratio of less than 1.63 clearly indicates a higher elastic modulus. In the pouring direction, the top area of the test block tended to form a macroscopic fracture surface earlier. By contrast, the compressibility of the bottom area was greater than that of the top area. The intensification of aggregate segregation widened the differences in the deformation and failure characteristics between the different areas. For samples with different uniformities, significant differences in local deformation ranging from 515.00 its to 1693.70 its were observed during the stable deformation stage. The extreme unevenness of the aggregate leads to rapid crack penetration in the sample, causing macroscopic tensile failure and resulting in premature structural failure.

The backfill should keep stable in the primary stope when mining an adjacent secondary stope in subsequent open stoping mining methods, and the large-size mined-out area is usually backfilled by multiple backfilling before the recovery of a secondary stope, resulting in a layered structure of backfill in stope. Therefore, it is significant to investigate the deformation responses and mechanical properties of stratified cemented tailings backfill (SCTB) with different layer structures to remain self-standing as an artificial pillar in the primary stope. The current work examined the effects of enhance layer position (1/3, 1/2, and 2/3) and thickness ratio (0, 0.1, 0.2, and 0.3) on the mechanical properties, deformation, energy evolution, microstructures, and failure modes of SCTB. The results demonstrate that the incorporation of an enhance layer significantly strengthens the deformation and strength of SCTB. Under a confining pressure of 50 kPa, the peak deviatoric stress rises from 525.6 to 560.3, 597.1, and 790.5 kPa as the thickness ratio of enhance layer is increased from 0 to 0.1, 0.2 and 0.3, representing a significant increase of 6.6%, 13.6% and 50.4%. As the confining pressure increases, the slopes of the curves in the elastic stage become steep, and the plastic phase is extended accordingly. Additionally, the incorporation of the enhance layer significantly improves the energy storage linit of SCTB specimen. As the thickness ratio of the enhance layer increases from 0 to 0.1, 0.2, and 0.3, the elastic energy rises from 0.54 to 0.67, 0.84, and 1.00 MJ·m⁻³, representing a significant increase of 24.1%, 55.6% and 85.2%. The internal friction angles and cohesions of the SCTB specimens are higher than those of the CTB specimens, however, the cohesion is more susceptible to enhance layer position and thickness ratio than the internal friction angle. The failure style of the SCTB specimen changes from shear failure to splitting bulging failure and shear bulging failure with the presence of an enhance layer. The crack propagation path is significantly blocked by the enhance layer. The findings are of great significance to the application and stability of the SCTB in subsequent stoping backfilling mines.

The growing demand for Ni and Co in the new energy sector necessitates efficient extraction methods for limonitic laterite ores. This study demonstrated the effectiveness of sodium sulfate (Na₂SO₄) as an additive for enhancing the co-enrichment of Ni and Co during solid-state reduction. Na₂SO₄ promoted the formation of two distinct liquid phases, low-melting-point FeS–FeO–Fe and NaAlSiO₄–NaFeSiO₄, facilitating the migration and aggregation of Ni–Co–Fe alloy particles, leading to a high-grade alloy powder with 11.98wt% Ni and 0.88wt% Co and recoveries of 94.03% and 80.16%, respectively. Ni–Co–Fe particle growth was mainly driven by the FeS–FeO–Fe eutectic melt, aligned with a liquid-phase sintering mechanism. Pilot-scale rotary kiln experiments validated the industrial feasibility of this approach, which offers a promising solution for the sustainable extraction of these critical metals.

This study explores a hydrogen-assisted mineral phase transformation process with synergistic desulfurization for the efficient recovery of iron from the high-pressure acid leach (HPAL) tailings of laterite nickel ore. HPAL tailings containing 51.50wt% iron and 2.09wt% sulfur present environmental challenges due to their sulfur content. Pre-treatment at 950°C for 15 min successfully reduced the sulfur content to 0.295wt% and increased the iron grade to 57.66wt%. Further hydrogen-assisted mineral phase transformation at 520°C for 30 min, using 40vol% hydrogen and a gas flow rate of 600 mL·min⁻¹, resulted in a product with an iron grade of 61.00wt% and 90.11% iron recovery. The overall desulfurization rate reached 85.83% when wet scrubbing and limestone were used to capture the sulfur. This study demonstrates the efficiency of this hydrogen-assisted process for sustainable iron recovery and sulfur removal from laterite nickel ore tailings, with potential for industrial applications.

This study analyzes the influence of TiO₂ and Al₂O₃ contents on the microstructure of CaO-SiO₂-MgO-xwt%Al₂O₃-ywt%TiO₂ (14 ≤ x ≤ 22, 0 ≤ y ≤ 10) blast furnace slag systems based on the change of slag viscosity, Raman spectroscopy, and molecular dynamics. The Raman spectroscopy results indicate that an increase in TiO₂ content leads to the gradual depolymerization of complex silicate structures (Q_Si³ and Q_Si²) into simpler structures (Q_Si⁰ and Q_Si¹) in the slag. At the same time, the Al-O-Al bonds in the aluminate structures of the slag also depolymerize into simpler Al-O⁻ forms, resulting in a decrease in the degree of polymerization of both silicates and aluminates. In contrast, an increase in Al₂O₃ content generally results in an increased degree of polymerization for the silicates and aluminates. Molecular dynamics simulations of the polymerization and depolymerization processes in the microstructure of the blast furnace slag reveal that Si and Al mainly exist in tetrahedral [SiO₄]⁴⁻ and [AlO₄]⁴⁻, while Ti mainly exists in the form of simple pentacoordinate [TiO₅]⁶⁻ and hexacoordinate [TiO₆]⁸⁻. TiO₂ exhibits basic properties in this system, whereas Al₂O₃ demonstrates acidic behavior. The addition of TiO₂ introduces free oxide ions into the system, causing the bridging oxygens to break into non-bridging oxygens, leading to the depolymerization of complex structures Q_Si⁴ and Q_Si³, which simplifies the slag structure. On the other hand, an increase in Al₂O₃ content tends to capture or share the oxide ions within the system to form [AlO₄]⁴⁻, resulting in the polymerization of free oxygens into non-bridging oxygens, which further polymerize into bridging oxygens and lead to the consolidation of simple structures Q_Si⁰ and Q_Si¹, resulting in a more complex slag structure. Both Raman spectroscopy analysis and molecular dynamics simulation results indicate that the degree of polymerization of [SiO₄]⁴⁻ and [AlO₄]⁴⁻ in the slag network structure is a crucial factor determining the fluidity of the slag.

With the gradual reduction in high-quality iron ore resources, the global steel industry faces long-term challenges. For example, the continuous increase in the Al₂O₃ content of iron ore has led to a decrease in the metallurgical performance of sinter and fluctuations in slag properties. Considering calcium ferrite (CF) and composite CF (silico-ferrite of calcium and aluminum, SFCA) play a crucial role as a binding phase in high-alkalinity sinter and exhibit excellent physical strength and metallurgical performance, we propose incorporating excess Al₂O₃ into SFCA to form a new binding phase with excellent properties for high-quality sinter preparation. In the synthesis of high-Al₂O₃ SFCA, two high-Al₂O₃ phases were identified as types A (Al_1.2Ca_2.8Fe_8.7O₂₀Si_0.8) and B (Ca₄Al_4.18Fe_1.82Si₆O₂₆). Results show that type A SFCA sample had a higher cell density (4.13 g/cm³) and longer Fe–O bond length (2.2193 Å) than type B (3.46 g/cm³ and 1.9415 Å), with a significantly greater lattice oxygen concentration (7.86% vs. 1.85%), which demonstrates advantages in strength and reducibility. Type A SFCA sample contained a lower proportion of silicates, was predominantly composed of SFCA, and exhibited minimal porosity. Melting point and viscosity simulation tests indicate that type A SFCA sample formed a liquid phase at 880°C with a viscosity range of 0–0.35 Pa·s, which is notably lower than that of type B SFCA sample (1220°C and 0–20 Pa·s). This finding suggests that type A SFCA sample has a low initial melting temperature and viscosity, which facilitates increasing liquid-phase generation and improving flow properties. Such a condition enhances the adhesion to surrounding ore particles. Compressive strength tests reveal that type A SFCA sample (36.83–42.48 MPa) considerably outperformed type B SFCA sample (5.98–12.79 MPa) and traditional sinter (5.02–13.68 MPa). In addition, at 900°C, type A SFCA sample achieved a final reducibility of 0.89, which surpassed that of type B SFCA sample (0.83). In summary, type A SFCA sample demonstrates superior structural, thermophysical, and metallurgical properties, which highlights its promising potential for industrial applications.

The endpoint carbon content in the converter is critical for the quality of steel products, and accurately predicting this parameter is an effective way to reduce alloy consumption and improve smelting efficiency. However, most scholars currently focus on modifying methods to enhance model accuracy, while overlooking the extent to which input parameters influence accuracy. To address this issue, in this study, a prediction model for the endpoint carbon content in the converter was developed using factor analysis (FA) and support vector machine (SVM) optimized by improved particle swarm optimization (IPSO). Analysis of the factors influencing the endpoint carbon content during the converter smelting process led to the identification of 21 input parameters. Subsequently, FA was used to reduce the dimensionality of the data and applied to the prediction model. The results demonstrate that the performance of the FA–IPSO–SVM model surpasses several existing methods, such as twin support vector regression and support vector machine. The model achieves hit rates of 89.59%, 96.21%, and 98.74% within error ranges of ±0.01%, ±0.015%, and ±0.02%, respectively. Finally, based on the prediction results obtained by sequentially removing input parameters, the parameters were classified into high influence (5%–7%), medium influence (2%–5%), and low influence (0–2%) categories according to their varying degrees of impact on prediction accuracy. This classification provides a reference for selecting input parameters in future prediction models for endpoint carbon content.

The extreme removal of SiO₂ and MnO inclusions in 304 stainless steel in supergravity fields was investigated using an in-house high-temperature supergravity equipment. The influences of the gravity coefficient and separation time on the removal efficiency of the inclusions were studied. After supergravity treatment, the inclusions migrated to the top of the sample and formed large aggregates. Meanwhile, the lower part of the sample was purified considerably and appeared significantly cleaner than the raw material. At the gravity coefficient of 500 and separation time of 600 s, the total oxygen content at the bottom of the sample (position E) decreased from 240 to 28 ppm. This corresponded to a total oxygen removal rate of 88.33%. The volume fraction and number density of inclusions exhibited a gradient distribution along the supergravity direction, with values of 8.5% and 106 mm⁻² at the top of the sample (position A) and 0.06% and 22 mm⁻² at its bottom.

Ultra-high strength steel (UHSS) fabricated via laser additive manufacturing (LAM) holds significant promise for applications in defense, aerospace, and other high-performance sectors. However, its response to high-impact loading remains insufficiently understood, particularly regarding the influence of energy density on its dynamic mechanical behavior. In this study, scanning electron microscopy, electron backscatter diffraction, and image recognition techniques were employed to investigate the microstructural variations of LAM-fabricated UHSS under different energy density conditions. The dynamic mechanical behavior of the material was characterized using a Split Hopkinson Pressure Bar system in combination with high-speed digital image correlation. The study reveals the spatiotemporal evolution of surface strain and crack formation, as well as the underlying dynamic fracture mechanisms. A clear correlation was established between the microstructures formed under varying energy densities and the resulting dynamic mechanical strength of the material. Results demonstrate that optimal material density is achieved at energy densities of 292 and 333 J/mm³. In contrast, energy densities exceeding 333 J/mm³ induce keyhole defects, compromising structural integrity. Dynamic performance is strongly dependent on material density, with peak impact resistance observed at 292 J/mm³—where strength is 8.4% to 17.6% higher than that at 500 J/mm³. At strain rates ≥ 2000 s⁻¹, the material reaches its strength limit at approximately 110 µs, with the initial crack appearing within 12 µs, followed by rapid failure. Conversely, at strain rates ≤ 1500 s⁻¹, only microcracks and adiabatic shear bands are detected. A transition in fracture surface morphology from ductile to brittle is observed with increasing strain rate. These findings offer critical insights into optimizing the dynamic mechanical properties of LAM-fabricated UHSS and provide a valuable foundation for its deployment in high-impact environments.

Nickel-based single-crystal (SX) superalloys are the key metallic materials of aeroengines. However, thermomechanical deformation always occurs during the directional solidification of SX superalloys, negatively influencing the SX structure. Casting deformation is simulated in most of the previous studies, whereas the direct simulation of dendritic thermomechanical deformation has been largely ignored, resulting in a lack of comprehensive understanding of this process. In this study, we systematically investigate dendritic thermomechanical deformation with a model coupled with dendrite growth, fluid flow, and thermomechanical deformation behavior. Results reveal that the dendritic thermomechanical deformation-induced dendrite bending is not randomly distributed but is mainly concentrated on the casting surface. The dendritic thermal stress increases as dendrite grows and accumulates after dendrite bridging. Transverse thermal contraction mainly occurs at the edge of casting in the corner, and axial thermal contraction is larger than transverse contraction. The high-stress region of the primary dendrite trunk is mainly distributed below the dendrite bridging near the solidified part, and the stress along the transverse direction reaches its maximum value on the casting surface. Stress concentrated on the casting surface is mainly attributed to variations in transverse temperature gradients caused by heat dissipation on the lateral mold wall, and inconsistent constraints in the lateral mold walls.

Mg-Zn-Mn alloys have the advantages of low cost, excellent mechanical properties, and high corrosion resistance. To clarify the phase equilibria of Mg-Zn-Mn alloy in the Mg-rich corners, the present work experimentally investigated the phase equilibria in the Mg-rich corner at 300-400°C with equilibrated alloy method using electron probe micro analyzer (EPMA), X-ray diffractometer (XRD), transmission electron microscopy (TEM), and differential scanning calorimeter (DSC). Mn atoms were found to dissolve into MgZn₂ to form a ternary solid-solution type compound, in which Mn content can be up to 15.1at% at 400°C. Three-phase equilibrium of α-Mg + MgZn₂ + α-Mn and liquid + α-Mg + MgZn₂ were confirmed at 400°C. Subsequently, thermodynamic modeling of the Mg-Zn-Mn system was carried out using the CALPHAD method based on the experimental data of this work and literature data. The calculated invariant reaction Liquid + α-Mn → α-Mg + MgZn₂ at 430°C shows good agreement with the DSC results. In addition, the results of solidification path calculations explain the microstructure in the as-cast and annealed alloys well. The agreement between the calculated results and experimental data proves the self-consistency of the thermodynamic database, which can provide guidance for the compositional design of Mg-Zn-Mn alloys.

Although the degradability and biosafety of magnesium alloys make them advantageous for biological applications, medical implants made of magnesium alloys often fail prematurely due to corrosion. Therefore, improving the corrosion resistance of magnesium alloys has become an urgent problem in the alloy design process. In this study, we designed and prepared Mg-xZn-0.5Y-0.5Zr (x = 1, 2, and 3, wt%) alloys in a hot extruded state and analyzed their surface structure through scanning electron microscopy, energy dispersion spectrometry, and X-ray diffraction. It was found that increasing the Zn content refined the recrystallized grains in the alloy. Particularly in Mg-3Zn-0.5Y-0.5Zr, the I phase became finer, forming both granular and nanoscale needle-like particles. Surface characterization after the immersion experiment showed that the corrosion product layer was mainly composed of Mg(OH)₂, Zn(OH)₂, CaCO₃, and hydroxyapatite. The degradation rate of ZW305K was the lowest, measured as 4.1 and 6.0 mm·a⁻¹ with the hydrogen precipitation method and weight loss method respectively. Electrochemical experiments further explained the corrosion circuit model of the alloy in solution and confirmed the earlier results. The maximum polarization resistance of ZW305K was 874.5 Ω·cm², and the lowest corrosion current density was 0.104 mA·cm⁻². As a biomedical alloy, it must exhibit good biocompatibility, so the alloy was also tested through cytotoxicity, cell adhesion, and staining experiments. The cell viability of each group after 48 h was greater than 80%, showing that the addition of zinc enhances the alloy’s biocompatibility. In summary, the prepared alloys have the potential to be used as biodegradable implant materials.

Micrometer-sized, irregularly shaped Ti particles (0.5wt% and 1.0wt%) were mixed with an Al-Si-Mg-Zr matrix powder, and a novel Ti-modified Al-Si-Mg-Zr aluminum alloy was subsequently fabricated via laser-powder bed fusion (L-PBF). The results demonstrated that the introduction of Ti particles promoted the formation of near-fully equiaxed grains in the alloy owing to the strong grain refinement of the primary (Al,Si)₃(Ti,Zr) nanoparticles. Furthermore, the presence of (Al,Si)₃(Ti,Zr) nanoparticles inhibited the decomposition of Si-rich cell boundaries and the precipitation of Si nanoparticles in the α-Al cells. The ultimate tensile strength (UTS), yield strength (YS), and elongation of the as-built 0.5wt% Ti (0.5Ti) alloy were (468 ± 11), (350 ± 1) MPa, and (10.0 ± 1.4)%, respectively, which are comparable to those of the L-PBF Al-Si-Mg-Zr matrix alloy and significantly higher than those of traditional L-PBF Al-Si-Mg alloys. After direct aging treatment at 150°C, the precipitation of secondary nanoparticles notably enhanced the strength of the 0.5Ti alloy. Specifically, the 0.5Ti alloy achieved a maximum UTS of (479 ± 11) MPa and YS of (376 ± 10) MPa. At 250°C, the YS of the L-PBF Ti/Al-Si-Mg-Zr alloy was higher than that of the L-PBF Al-Si-Mg-Zr matrix alloy due to the retention of Si-rich cell boundaries, indicating a higher thermal stability. As the aging temperature was increased to 300°C, the dissolution of Si-rich cell boundaries, desolvation of solid-solution elements, and coarsening of nanoprecipitates led to a decrease in the UTS and YS of the alloy to below 300 and 200 MPa, respectively. However, the elongation increased significantly.

The heteroepitaxy of diamond films has received widespread attention; however, its application remains limited owing to the mismatch in properties and structure between diamond and heterogeneous substrates. In this study, diamond films were successfully synthesized on high-entropy alloys (HEAs) substrates using microwave plasma chemical vapor deposition. The resulting diamond films were continuous, uniform, and adhered to the HEAs substrates. The mixed carbides were identified using X-ray diffraction, and the quality of the diamond films was examined using Raman spectroscopy. Moreover, the corrosion test revealed that the diamond/TiZrHfMo samples had excellent electrochemical stability and corrosion resistance with a corrosion potential value of −0.169 V in a 3.5wt% NaCl solution. A multiple regression model was established to evaluate the effects of the structure and growth parameters, which confirmed that the mixing entropy significantly affected the grain size and corrosion properties.

Lead-free vacancy-ordered double perovskites have emerged as promising materials for optoelectronic applications due to their environmentally friendly characteristics and exceptional properties. However, conventional synthesis methods often depend on toxic reagents and stringent conditions, limiting their large-scale synthesis and practical application. In this work, an environmentally friendly synthesis route was proposed for preparing vacancy-ordered double perovskites Cs₂SnX₆ (X = Cl, Br, and I) with high crystallinity under low-temperature and ambient-pressure conditions. This method utilizes ion liquid (i.e., 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-butyl-3-methylimidazolium bromide ([Bmim]Br) and 1-butyl-3-methylimidazolium iodide ([Bmim]I)) in combination with saturated aqueous solutions of ammonium halides as solvents, replacing traditional hydrogen halide acid or polar organic solvents. Experimental and characterization results demonstrate that the Cs₂SnX₆ (X = Cl, Br, and I) possess high crystallinity, well-defined morphology, and improved thermal stability. These improvements are attributed to the hydrogen bonding interactions between ionic liquids and the perovskite precursors. Additionally, the halogen-rich environment provided by ionic liquids and ammonium halide salts facilitates defect passivation. Furthermore, this method is applicable to the synthesis of doped perovskite crystals, demonstrated by the successful synthesis of Bi-doped Cs₂SnCl₆ crystals with a photoluminescence quantum efficiency of 12.73%. This study presents a novel strategy for synthesizing high-quality vacancy-ordered double perovskites and their doping or alloyed compounds.

The luminescence behavior of Eu³⁺-activated lanthanum tungstate nanophosphors exhibiting intense red emission was systematically explored by modifying their surfaces using various agents, including polyvinylpyrrolidone (PVP), cetyltrimethylammonium bromide (CTAB), trisodium citrate (TC), polyvinyl alcohol (PVA), and ethylene glycol (EG). These nanophosphors were synthesized via a facile hydrothermal-assisted solid-state reaction. X-ray diffraction (XRD) analysis confirmed the orthorhombic crystal structure of all the prepared samples. Morphological and size analyses were performed using scanning electron microscopy (SEM) and particle size distribution profiling. High-resolution transmission electron microscopy (HRTEM) complemented by elemental mapping was used to evaluate the particle dimensions and interplanar spacing of the optimized sample. Fourier-transform infrared spectroscopy (FTIR) was used to identify functional groups and assign corresponding vibrational bands. X-ray photoelectron spectroscopy (XPS) provided insights into the elemental composition and binding energies of the optimized nanophosphors. Notably, the PVA-modified sample doped with 14mol% Eu³⁺ exhibited pronounced red emission at 616 nm, attributed to the ⁵D₀→⁷F₂ electric dipole transition of Eu³⁺ ions under ultraviolet (UV) excitation. Detailed excitation and emission spectral analyses were performed, with band assignments corresponding to the relevant electronic transitions. Among the surface-treated variants, the PVA-modified nanophosphors demonstrated exceptional color purity of 99.6%, international commission on illumination (CIE) chromaticity coordinates of (0.6351, 0.3644), and a correlated color temperature of 1147 K. These superior optical features are ascribed to the enhanced surface passivation and suppression of nonradiative recombination, facilitated effectively by the PVA surface layer. Lifetime decay analysis across all samples revealed a significantly extended lifetime for the optimized composition, further supporting its superior luminescence efficiency. In addition, evaluation of the biocompatibility of the nanophosphors highlighted their potential for biomedical applications. Overall, these findings emphasize the efficacy of PVA-modified Eu³⁺-doped lanthanum tungstate nanophosphors as highly efficient red emitters, suitable for application in white light-emitting diodes (WLEDs) and latent fingerprint detection while offering valuable insights into the role of surface modification in tuning the optical properties of nanophosphors.