La2O3 Nanoparticles Research Articles

Development of High-Performance Ethanol Gas Sensors Based on La2O3 Nanoparticles-Embedded Porous SnO2 Nanofibers

Porous pure SnO2 nanofibers (NFs) and La2O3 nanoparticles (NPs)-embedded porous SnO2 NFs were successfully synthesized via electrospinning followed by calcination. These materials were systematically evaluated as gas-sensing elements in metal-oxide-semiconductor (MOS) sensors. The La2O3 NPs embedded in porous SnO2 NFs demonstrated superior gas-sensing performance compared to pure SnO2 NFs. Specifically, the incorporation of La2O3 resulted in a 12-fold enhancement in gas-sensing response towards ethanol, significantly improving both sensitivity and selectivity by tuning the carrier concentration and modifying oxygen deficiencies and chemisorbed oxygen levels. Thus, La2O3 NPs embedded in SnO2 NFs present a promising strategy for the development of high-performance ethanol gas sensors.

Time-Dependent Hydrothermal Synthesis of La2O3 NPs for Effective Catalytic Activity of Ionic Dye.

Lanthanum oxide was successfully synthesized by hydrothermal method by varying the reaction time such as 6, 12, and 24 h. In XRD, study confirms the presence of a hexagonal structure, and the phase remains the same at different times; the main goal is to assess the average crystallite size of prepared La2O3 nanoparticles, which was found in the range of 6 to 8 nm. An interesting observation from the XRD data was the apparent increase in crystalline nature as the synthesis time was extended. The UV-Vis spectroscopic studies show a change in the band gap when the reaction time is changed. The morphology analysis shows that the image revealed that the particles formed were agglomerated and formed a spherical shape, with diameters ranging between 35 and 86 nm. When tested for photocatalytic activity, the La2O3 nanoparticles show a degradation of methylene blue dye when the time varies. Remarkably, the nanoparticles synthesized exhibited a profound ability to degrade the dye, with an efficiency rate hitting as high as 89% under halogen light illumination.

Trophic Transfer of Metal Oxide Nanoparticles in the Tomato-Helicoverpa armigera Food Chain: Effects on Phyllosphere Microbiota, Insect Oxidative Stress, and Gut Microbiome.

Understanding the trophic transfer and ecological cascade effects of nanofertilizers and nanopesticides in terrestrial food chains is crucial for assessing their nanotoxicity and environmental risks. Herein, the trophic transfer of La2O3 (nLa2O3) and CuO (nCuO) nanoparticles from tomato leaves to Helicoverpa armigera (Lepidoptera: Noctuidae) caterpillars and their subsequent effects on caterpillar growth and intestinal health were investigated. We found that 50 mg/L foliar nLa2O3 and nCuO were transferred from tomato leaves to H. armigera, with particulate trophic transfer factors of 1.47 and 0.99, respectively. While nCuO exposure reduced larval weight gain more (34.7%) than nLa2O3 (11.3%), owing to higher oxidative stress (e.g., MDA and H2O2) and more serious intestinal pathological damage (i.e., crumpled columnar cell and disintegrated goblet cell) by nCuO. Moreover, nCuO exposure led to a more compact antagonism between the phyllosphere and gut microbiomes compared to nLa2O3. Specifically, nCuO exposure resulted in a greater increase in pathogenic bacteria (e.g., Mycobacterium, Bacillus, and Ralstonia) and a more significant decrease in probiotics (e.g., Streptomyces and Arthrobacter) than nLa2O3, ultimately destroying larval intestinal immunity. Altogether, our findings systematically revealed the cascade effect of metal oxide nanomaterials on higher trophic consumers through alteration in the phyllosphere and insect gut microbiome interaction, thus providing insights into nanotoxicity and environmental risk assessment of nanomaterials applied in agroecosystems.

Study on forming process and performance of nano-La2O3 reinforced tungsten-based composites by selective laser melting

In this study, La2O3 nanoparticles were incorporated into a tungsten (W) matrix to enhance the microstructure and properties of pure W. The selective laser melting (SLM) process for W-2wt% La2O3 was optimized, and the influence of SLM processing parameters on the relative density and internal defects of the samples was examined. Challenges such as uneven powder layering and layer-by-layer thickening during the SLM process were addressed by incorporating a homogeneous material support formed with low laser energy density beneath the sample. This approach widened the process window for sample formation, resulting in a 2.38 % increase in the average relative density of supported samples compared to unsupported ones.With optimized parameters of 240W laser power, 200 mm/s scanning speed, and 80 μm hatch spacing, the sample achieved a relative density of 98.32 % with minimal internal pores, though some microcracks remained. Further investigation revealed that surface roughness decreased with increasing laser power and scanning speed. High laser power combined with low scanning speed yielded good surface quality. Under conditions of high relative density (over 96 %), samples processed with low laser power and high scanning speed (200W, 200 mm/s) exhibited fine and uniform grain morphology, few internal defects, and excellent mechanical properties, with a microhardness of 474HV and a compressive strength of 2237 MPa.

Novel Synthesis and Characterization of Lanthanum oxide Nanoparticles from Nano-sized Lanthanum(III) Compound

A new nano-sized La (III) compound, La[(N2H4)2{C10H6(3-O)(2-COO)}1.5].H2O (X), was synthesized by the sonochemical method and characterized by field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD) and elemental analyses. Lanthanum oxide nanoparticles were prepared by direct thermal decomposition of nanostructures in a programmable furnace up to 800 ℃ in ambient atmosphere. The structural characterization was done by powder XRD, and morphological observations by FESEM revealed that the quasi-spherical La2O3 nanoparticles obtained are well crystallized and uniform in both morphology and particle size. The study demonstrates that supramolecular compounds may be suitable precursors for the simple one-pot preparation of nanoscale metal oxide materials with different morphologies.

The origin of exceptionally large ductility in molybdenum alloys dispersed with irregular-shaped La2O3 nano-particles

Molybdenum and its alloys are known for their superior strength among body-centered cubic materials. However, their widespread application is hindered by a significant decrease in ductility at lower temperatures. In this study, we demonstrate the achievement of exceptional ductility in a Mo alloy containing rare-earth La2O3 nanoparticles through rotary-swaging, a rarity in Mo-based materials. Our analysis reveals that the large ductility originates from substantial variations in the electronic density of states, a characteristic intrinsic to rare-earth elements. This characteristic can accelerate the generation of oxygen vacancies, facilitating the amorphization of the oxide-matrix interface. This process promotes vacancy absorption and modification of dislocation configurations. Furthermore, by inducing irregular shapes in the La2O3 nanoparticles through rotary-swaging, incoming dislocations interact with them, creating multiple dislocation sources near the interface. These dislocation sources act as potent initiators at even reduced temperatures, fostering diverse dislocation types and intricate networks, ultimately enhancing dislocation plasticity.

Investigating the physical and electrical properties of La2O3 via annealing of La(OH)3

A simple technique was utilized to fabricate pure hexagonal La2O3 nanorods by utilizing lanthanum(III) nitrate hexahydrate (La(NO3)3·6H2O) and ammonia (NH4OH). The La2O3 nanoparticles were analyzed using XRD, TGA, Raman, SEM, FTIR, TEM, PL spectroscopy, and Mott–Schottky techniques. The XRD analysis confirmed the production of La(OH)3 nanorods under appropriate conditions, which were then successfully converted into La2O2CO3 and finally into La2O3 nanorods through annealing. The TGA analysis showed that the total weight loss was due to water evaporation and the dissolution of minimal moisture present in the environment. The FTIR analysis confirmed the presence of functional groups. The SEM analysis revealed changes in morphology. The TEM analysis to determine the particle size. The PL findings showed three emission peaks at 390, 520, and 698 nm due to interband transitions and defects in the samples. The Mott–Schottky analysis demonstrated that the flatband potential and acceptor density varied with annealing temperature, ranging from 1 to 1.2 V and 2 × 1018 to 1.4 × 1019 cm−3, respectively. Annealing at 1000 °C resulted in the lowest resistance to charge transfer (Rct).

Preparation of PEI/La2O3/Polypropylene fiber filter for household water purifiers and investigation of its phosphate reduction and bacterial control

It has been accepted that limiting phosphate is a prerequisite for bacterial inactivation in tap water. La2O3 nanoparticles were loaded onto polypropylene (PP) fibers through the method of melt spinning. Hydrophilic modification of the adsorbent surface was performed using polyethyleneimine (PEI) to prepare PEI/La2O3/PP. The results indicated that the optimal loading amount of La2O3 was 1 %, and the optimal concentration of PEI was 1 %. The successful loading of La2O3 resulted in a roughened fiber surface and increased fiber diameters. After PEI modification the water contact angle was reduced from 98° to 50°. The pHzpc of PEI/La2O3/PP was determined to be 8.3. The co-existing ions have little effect on phosphate adsorption. Phosphate adsorption can be well described by Redlich-Peterson model with a maximum KR-P of 3.98 × 10−5 L/mg. Adsorption kinetics fit well with the pseudo-second-order reaction equation. The activation energy (Ea) is determined to be 57.9 kJ/mol, providing the evidence of chemical nature of the reaction involving phosphate ions on the surface of PEI/La2O3/PP. The PEI/La2O3/PP adsorbent can reduce the phosphate concentration in tap water to below 0.01 mg/L, leading to a reduction in Escherichia coli concentration from approximately 10,000 CFU/mL to around 10 CFU/mL. The survival rates of Escherichia coli in a multi-nutrient environment are higher than in a single phosphate source environment. Our research provides a new feasible approach for ensuring microbial water quality safety in household water purifiers.

La2O3 Nanoparticles Can Cause Cracking of Tomato Fruit through Genetic Reconstruction.

La2O3 nanoparticles (NPs) have shown great potential in agriculture, but cracking of plant sensitive tissue could occur during application, resulting in a poor appearance, facilitating entry for insects and fungi, and increasing economic losses. Herein, exocarp cracking mechanisms of tomato (Solanum lycopersicum L.) fruit in response to La2O3 NPs were investigated. Tomato plants were exposed to La2O3 NPs (0-40 mg/L, 90 days) by a split-root system under greenhouse condition. La2O3 NPs with high concentrations (25 and 40 mg/L) increased the obvious cracking of the fruit exocarp by 20.0 and 22.7%, respectively. After exposure to 25 mg/L La2O3 NPs, decreased thickness of the cuticle and cell wall and lower wax crystallization patterns of tomato fruit exocarp were observed. Biomechanical properties (e.g., firmness and stiffness) of fruit exocarp were decreased by 34.7 and 25.9%, respectively. RNA-sequencing revealed that the thinner cuticle was caused by the downregulation of cuticle biosynthesis related genes; pectin remodeling, including the reduction in homogalacturonan (e.g., LOC101264880) and rhamnose (e.g., LOC101248505), was responsible for the thinner cell wall. Additionally, genes related to water and abscisic acid homeostasis were significantly upregulated, causing the increases of water and soluble solid content of fruit and elevated fruit inner pressure. Therefore, the thinner fruit cuticle and cell wall combined with the higher inner pressure caused fruit cracking. This study improves our understanding of nanomaterials on important agricultural crops, including the structural reconstruction of fruit exocarp contributing to NPs-induced cracking at the molecular level.

Solution combustion synthesis of Dy3+doped La2O3 nanoparticles: An investigation of their structural, optical and photoluminescence characteristics

The impact of the varying Dy3+ (1–9 mol %) rare earth ion concentration on the structural and luminous characteristics of La2O3 phosphors was studied via solution combustion synthesis. Structure formation, photoluminescence (PL) effectiveness, optical properties, and energy transfer mechanisms were examined in detail. All the synthesised samples exhibits hexagonal structure, which is supported by X-ray diffraction patterns (space group: P-3 mL (164)). Scanning electron microscope analysis shows irregular particle size and shapes of the synthesised materials. The presence of prominent and dominant Dy3+ ion peaks in the excitation spectrum of the ideal sample material, correlate to the Dy3+ ion's absorption peaks, supports the existence of considerable energy transfer among La3+ and Dy3+ ions. The PL emission wavelengths at 486 and 570 nm assigned to the Dy3+ ions transitions 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 respectively owing to the charge-transfer between La3+ and Dy3+ ions. PL emission intensity increases up to 3 mol% and afterwards it starts to decrease due to concentration quenching caused by non-radiative interactions. Photometric properties were investigated to check the possible utilization of La2O3:Dy3+ phosphor in white light emitting diodes application with CIE (x- 0.3468, y- 0.3986), CCT (0.1957, 0.5060), and colour purity (23.8 %). Aforementioned findings suggest that the synthesized phosphor is a viable option for making w-LEDs using NUV chips serving as the source of excitation.

Microstructure, Mechanical Properties, and Corrosion Resistance of Ag-Cu Alloys with La2O3 Fabricated by Selective Laser Melting.

Ag and its alloys, when prepared by a selective laser melting (SLM) process, have a low density and poor overall performance due to their high reflectivity when the most commonly used laser (λ = 1060 nm) is used, and they have exorbitant thermal conductivity. These characteristics lead to the insufficient melting of the powders and severely limit the applications of additive manufactured silver alloys. To improve the absorption of the laser, as well as for better mechanical properties and higher resistance to sulfidation, Ag-Cu alloys with different La2O3 contents were prepared in this work using the SLM process, via the mechanical mixing of La2O3 nanoparticles with Ag-Cu alloy powders. A series of analyses and tests were conducted to study the effects of La2O3 in Ag-Cu alloys on their density, microstructure, mechanical properties, and corrosion resistance. The results revealed that the addition of La2O3 particles to Ag-Cu alloy powders improved the laser absorptivity and reduced defects during the SLM process, leading to a significant rise from 7.76 g/cm3 to 9.16 g/cm3 in the density of the Ag-Cu alloys. The phase composition of the Ag-Cu alloys prepared by SLM was Silver-3C. La2O3 addition had no influence on the phase composition, but refined the grains of the Ag-Cu alloys by inhibiting the growth of columnar grains during the SLM process. No remarkable preferred orientation existed in all the samples prepared with or without La2O3. An upwards trend was achieved in the hardness of the Ag-Cu alloy by increasing the contents of La2O3 from 0 to 1.2%, and the average hardness was enhanced significantly, from 0.97 GPa to 2.88 GPa when the alloy contained 1.2% La2O3 due to the reduced pore defects and the refined grains resulting from the effects of the La2O3. EIS and PD tests of the samples in 1% Na2S solution proved that La2O3 addition improved the corrosion resistance of the Ag-Cu alloys practically and efficaciously. The samples containing La2O3 exhibited higher impedance values and lower corrosion current densities.

Fabrication and microstructure characterization of W-La2O3-Y2O3 composites by spark plasma sintering and hot isostatic pressing

The fabrication of dense W composites dispersed with La2O3 and Y2O3 nanoparticles had been attempted by combining a spark plasma sintering with post hot isostatic pressing. W powders dispersed with La2O3 particles were prepared by ultrasonic spray pyrolysis using ammonium metatungstate hydrate and lanthanum nitrate, and then yttrium nitrate was added to finally synthesize W-La2O3-Y2O3 composite powders. TEM analysis revealed that La2O3 and Y2O3 nanoparticles were uniformly distributed in the synthesized W composite powders. The relative density of composites prepared by spark plasma sintering was found to increase with increasing amounts of oxide particles and also with post hot isostatic pressing. The densified composites containing 1 wt% each of La2O3 and Y2O3 particles showed smaller grain size and higher hardness than that containing 0.5 wt% each of oxide particles. Changes in relative density, grain size and hardness with the oxide content are discussed considering the observed microstructural features and the role of oxide particles in mass transport and grain growth.

Composition and Electronic Structure of La2O3/CNFs@C Core-Shell Nanoparticles with Variable Oxygen Content.

La2O3 nanoparticles stabilized on carbon nanoflake (CNF) matrix were synthesized and graphitized to produce core-shell structures La2O3/CNFs@C. Further oxidation of these structures by nitric acid vapors for 1, 3 or 6 h was performed, and surface-oxidized particles La2O3/CNFs@C_x (x = 1, 3, 6) were produced. Bulk and surface compositions of La2O3/CNFs@C and La2O3/CNFs@C_x were investigated by thermogravimetric analysis and X-ray photoelectron spectroscopy. With increasing the duration of oxidation, the oxygen and La2O3 content in the La2O3/CNFs@C_x samples increased. The electronic structures of samples were assessed by electron paramagnetic resonance. Two paramagnetic centers were associated with unpaired localized and mobile electrons and were registered in all samples. The correlation between bulk and surface compositions of the samples and their electronic structures was investigated for the first time. The impact of the ratio between sp2- and sp3-hybridized C atoms, the number and nature of oxygen-containing groups on the surface and the presence and proportion of coordinated La atoms on the EPR spectra was demonstrated.

Synthesis, characterization and electrochemical detection of tartaric acid and grape juice using rGO doped La2O3 nanoparticles

The paper describes the synthesis of a reduced graphene oxide (rGO)/lanthanum oxide (La2O3) nanocomposite utilizing a simple reflux method. The presence of lanthanum oxide nanoparticles was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDAX), and Fourier-transform infrared spectroscopy (FTIR) analysis. rGO and La2O3/rGO had average crystallite sizes (D) of 14.96nm and 22.83 nm, respectively. Using cyclic voltammetry (CV) and Differential pulse voltammetry (DPV), electrochemical detection of tartaric acid (TA) and grape juice was done on synthesized material. The La2O3/rGO electrode was used to measure tartaric acid and grape juice concentrations, and the detection limits of both sensors were determined to be 151 μM and 127 μM respectively. The La2O3/rGO electrode also has a larger surface area.

Unveiling the photocatalytic property of La2O3–CuO nanocomposites for organic pollutants in wastewater treatment

Photocatalytic degradation was considered the best strategy for removing hazardous dye contaminants in water bodies from wastewater. The photocatalyst of pure La2O3 nanoparticles and La2O3–CuO nanocomposites synthesized by sonochemical method. The nanocomposites were used to investigate the degradation activity of Safranin (SR) and crystal violet (CV) under sunlight irradiation. The physicochemical characterization methods (e.g., Field emission scanning electron microscopy (FESEM), high resolution-transmission electron microscopy (HR-TEM), ultraviolet, visible spectroscopy (UV–Vis), and BET analysis indicate that the composite has been constructed successfully that enhances the widened visible light absorption, induces charge transfer and separation efficiency of electron–hole pairs. X-ray diffraction (XRD) experiment demonstrated that introducing copper into lanthanum resulted in alterations in the size of the crystallites and the average size of the nanoparticles, shifting from 21.93 to 43.19 nm. The photocatalytic activity of all samples was examined through the photodegradation of Safranin and crystal violet in an aqueous medium. The photocatalytic degradation rate of nanocomposite catalysts could eliminate 95.80 % and 97.05 % of Safranin and crystal violet dyes in 135 min, about 1.4 times that of pure La2O3 nanoparticles. The current study will give an efficient nanocomposite photocatalyst for removing biological and textile dye aqueous pollutants.

A La2O3/MXene composite electrode for supercapacitors with improved capacitance and cycling performance

ABSTRACT Developing efficient electrode materials is a key towards high power electrochemical energy storage devices. Two-dimensional (2D) MXene shows excellent conductivity and electrochemical performance among other materials. However, the restacking of MXene layers may degrade their specific capacity and cycling performance. Considering this challenge, here we have designed a composite made of 2D MXene nanosheets and lanthanum oxide (La2O3) nanoparticles to overcome the limitations. The bifunctionality of La2O3 nanoparticles prevents the restacking of MXene layers and enhances the electrochemical properties of the electrode due to its good Faradic characteristics. The specific capacitance of the La2O3/MXene composite electrode is 366 F/g at 1 A/g, which is 4.5 and 3 times higher than those of the individual La2O3 and MXene. The composite electrode displays a capacitance retention of 96% after 1,000 cycles, which is due to synergistic effects between the two components and indicates the potential of La2O3/MXene composite for supercapacitors.

Simultaneous regulation of strength and ductility of laser powder bed fusion manufactured Haynes 230 alloy

Haynes 230 alloy is widely used in aero-engines with high strength, fatigue resistance, oxidation resistance and other properties. However, the powder metallurgy process limits its application due to hot cracks and low strength. In this work, crack inhibition and mechanical properties improvement of the laser powder bed fusion (L-PBF) manufactured Haynes 230 alloy using 25 groups of different laser energy densities and scanning strategies were investigated. Results show that the high density, nearly crack-free, fine microstructure, and excellent strength and ductility were achieved by a laser energy density of 59.4 J/mm3 and rotation angle of 90° for the L-PBF manufactured Haynes 230 alloy. The microstructure was composed of γ matrix, carbides (M6C, M23C6), and La2O3 nanoparticles. Interestingly, many carbides were found to be mainly uniformly distributed at the grain or sub-grain boundaries with the following orientation relation: [011]γ//[011]M23C6. Simultaneously, by adjusting laser energy density and scanning strategy, the liquid film, low-melting eutectic phase, hot stress concentration, and high-angle grain boundaries (HAGBs) were suppressed, and the hot cracks were reduced. In addition, yield strength and ultimate tensile strength enhancement of the L-PBF manufactured Haynes 230 alloy was attributed to the synergistic effect of solid solution strengthening, dislocation strengthening, Orowan strengthening, and grain refinement. Whereas ductility enhancement was the main effect of defect inhibition, grain refinement, and nanoprecipitate. This work has verified the feasibility of crack inhibition and mechanical properties improvement of the L-PBF manufactured Haynes 230 alloy by various laser energy densities and scanning strategies.

Foliar spray of La2O3 nanoparticles regulates the growth, antioxidant parameters, and nitrogen metabolism of fragrant rice seedlings in wet and dry nurseries.

Nanoparticles (NPs) have been widely used in agriculture, and lanthanum oxidenanoparticles (La2O3) NPs can regulate plant growth. La2O3 NPs treatment was hypothesized to affect the accumulation and distribution of substances in rice seedlings under wet and dry nursery conditions. The objective of the present study was to ascertain the effects of La2O3 NPs foliar spray on the morphology and physiology of fragrant rice seedlings under wet and dry nursery conditions. Seedlings of two fragrant rice cultivars, namely 'Xiangyaxiangzhan' and 'Yuxiangyouzhan,' were grown under wet and dry nursery conditions with La2O3 NPs treatments at three concentrations (CK, La2O3 NPs 0mg L-1; T1, La2O3 NPs 20mg L-1; and T2, La2O3 NPs 40mg L-1). The results showed that the seedling-raising method was significantly associated with La2O3 NPs application (P < 0.05), affecting the leaf area of both cultivars. Changes in plant morphological parameters, such as dry weight and root-shoot ratio, were the reasons for the differences in cultivars in response to La2O3 NPs application. Changes were also observed in the plant morphological and physiological parameters of leaf area, specific leaf area, chlorophyll contents, antioxidant properties, and activities of nitrogen metabolism enzymes. The relationship between morphological and physiological processes in fragrant rice was investigated to test the hypothesis. In both wet and dry nursery methods, the T2 concentration of La2O3 NPs was beneficial for rice seedlings and significantly increased their leaf area due to changes in morphological and physiological parameters. Therefore, the results of this study provide a theoretical basis for expanding the research on La2O3 NPs application in rice, as well as relevant references for strengthening rice seedlings in the nursery, which has a positive effect on the grain yield improvement in fragrant rice.

Sonochemical synthesis of Sn-doped La2O3 nanoparticles and its application for the photocatalytic degradation of hazardous pollutants

Sonochemical synthesis of Sn-doped La2O3 nanoparticles and its application for the photocatalytic degradation of hazardous pollutants

Influence of nano additives on performance and emissions characteristics of a diesel engine fueled with watermelon methyl ester

Significant population and automobile expansion have resulted in a rapid rise in energy demand. Because of the high demand for energy and the rapid depletion of fossil fuels, experts are concentrating their efforts on developing a suitable alternative fuel for diesel. The performance and emission characteristics of biodiesel made from watermelon methyl ester were investigated using a lanthanum oxide (La2O3) nanoparticle addition. Through the transesterification meth od, biodiesel was produced from non-edible watermelon seed oil. Compared to B20, addition of 100 parts per million (ppm) of La2O3 nanoparticles to biodiesel emulsion fuel reduces CO and HC emissions by 4.75% and 6.67%, respectively. Compared to B20 at full load circumstances, the inclusion of La2O3 nanoparticles at 100 ppm enhances the brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) by 2% and 8.8%, respectively.