Li1.3Al0.3Ti1.7(PO4)3 ceramic electrolyte fabricated from bimodal powder precursor

A novel approach is proposed to design high-quality NASICON–type solid-state electrolytes (SSEs) based on Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) by incorporating nanoparticles into a matrix of microparticles, which could efficiently improve densification of LATP SSEs by sintering. Moreover, LATP SSEs with bimodal microstructures are obtained by tuning mass ratio of 60 nm and 600 nm ceramic particles, which are fabricated by sol-polymer and molten quenching methods, respectively. The LATP SSE containing 60 nm and 600 nm particles with the mass ratio of 10%/90% displays a high ionic conductivity of (5.93 ± 0.24)× 10⁻⁴ S/cm at room temperature and relative density of 95.5 ± 1.1% after sintering at 900 °C for 6 h. Besides, the Li||LATP||Li symmetric cell with the mass ratio of 10%/90% exhibits better cyclic stability with a steady polarization voltage of 121.2 mV than that of other ratios. Therefore, SSEs with multimodal microstructures pave a promising venue for practical application of high-energy-density and safe solid-state Li metal battery.     

‘Nano-tree’—type spherical polymer brush particles as templates for metallic nanoparticles

We present a new type of spherical polymer brush particles that consist of a solid poly(styrene) core (diameter: ca. 100 nm) onto which chains of a bottlebrush polymer have been densely grafted. These systems were prepared in aqueous dispersion by photo emulsion-polymerization using the macromonomer poly(ethylene glycol) methacrylate (PEGMA). In opposite to conventional spherical polyelectrolyte brushes carrying linear polymer chains, the system prepared here has a shell consisting of regularly branched chains (‘nano-tree’-type morphology). The branches consist of oligo(ethylene glycol) chains (n=13) terminated by a hydroxyl group. We demonstrate that these particles can be used as nanoreactors for the generation and immobilization of well-defined silver nanoparticles. Cryo-TEM and FESEM images show that Ag nanoparticles with diameter of ∼7.5±2 nm are homogeneously embedded into the PS-PEGMA brushes. Moreover, the composite particles exhibit an excellent colloidal stability. The catalytic activity is investigated by monitoring the reduction of 4-nitrophenol by NaBH₄ in presence of these silver nano-composite particles. The rate constant k_app was found to be strictly proportional to the total surface of the nanoparticles in the system. The study of the temperature dependence shows that the rate constants k_app obtained at different temperatures leads to an activation energy of 62 kJ/mol.     

Synthesis and responsive behavior of poly(N,N-dimethylaminoethyl methacrylate) brushes grafted on silica nanoparticles and their quaternized derivatives

Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) was grafted onto the surface of silica nanoparticles via surface-initiated atom transfer radical polymerization to form temperature- and pH-responsive PDMAEMA brushes (silica-g-PDMAEMA). The resultant samples were characterized via ¹H NMR, transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Their molecular weights and molecular weight distributions were determined by gel permeation chromatography analysis after silica content etching. The control of brush thickness and the responsive behavior were systematically investigated. Dynamic light scattering (DLS) results indicate that the brush thickness can be controlled by changing the polymerization time and the DMAEMA, initiator, and THF concentrations. According to DLS and zeta potential results, the lower critical solution temperature (LCST) of the PDMAEMA brushes shifts to a higher temperature with decreasing solution pH, which is attributed to the weak charge of the polyelectrolyte brushes. When the temperature is kept above the transition temperature, the silica-g-PDMAEMA nanoparticles aggregate into clusters and disaggregate during the cooling process. Moreover, with the heating/cooling step increasing, the aggregation and disaggregation temperatures are decreased. Meanwhile, when the molecular weight is increased from 13.6 × 10⁴ to 23.1 × 10⁴ g/mol, a decrease in the LCSTs at constant pH is observed. The related properties of the corresponding quaternized analog, poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI) brushes, were also discussed. The hydrodynamic radius of the silica-g-PMETAI nanoparticles decreases with increasing ionic strength, and a salting-out/salting-in effect is observed when the ionic strength is adjusted using NaI instead of NaCl.     

Chemical synthesis,compositional, morphological,structural, optical and magnetic properties of Zn1−xDyxS nanoparticles

Zn_1−xDy_xS (x=0, 0.02 and 0.04) nanoparticles (NPs) were synthesized by chemical refluxing technique at 100 °C. The prepared samples were analyzed by studying their compositional, morphological, structural, optical and magnetic properties. EDS analysis confirmed the presence of zinc, dysprosium and sulfur in the samples in near stoichiometric ratio. The X-ray diffraction patterns do not show any Dy related peaks for the as-synthesized ZnS nanoparticles. The average diameter of the particles confirmed by TEM studies, was in the range 2–4 nm. Raman studies revealed that all the samples are single phase and exhibit cubic structure. From DRS studies, the band-gap was found to be in the range of 3.85–3.70 eV. All the doped ZnS nanoparticles exhibit ferromagnetic behavior with the Curie temperature higher than room temperature and the magnetic properties of doped ZnS nanoparticles depend on the concentration of Dy ions.     

Synthesis of water dispersible magnetite nanoparticles in the presence of hydrophilic polymers

Water dispersible magnetite nanoparticles (Fe₃O₄) were synthesized by thermal decomposition of iron (III) acetylacetonate (Fe(acac)₃) in the presence of carboxylic acid-terminated poly(ethylene glycol) (mPEG acid), poly(vinyl alcohol) and NH₂-containing polyether. Crystal structure was investigated using X-ray diffractometry (XRD) and it showed that the as-synthesized particles had high crystallinity with distinct lattices. Particle size of the nanoparticles was investigated using XRD (15.32 nm), transmission electron microscopy (18.8 nm) and photo correlation spectroscopy (32 nm) techniques. Vibrating sample magnetometry indicated that magnetite nanoparticles exhibited superparamagnetic behavior at room temperature. Influence of each functional group on magnetic properties of the particles was also examined. These magnetite nanoparticles remained dispersible in aqueous dispersions with only 5% particles aggregating after 1 month of preparing.     

Janus gold nanoparticle with bicompartment polymer brushes templated by polymer single crystals

Janus particles have attracted increasing attention from the communities of materials science, chemistry, physics and biology. While large size Janus particles are readily achieved, synthesizing Janus nanoparticles (JNP) with diameters smaller than ∼20 nm remains a challenging task. In this article, we report a systematic study on growing polymer brushes on polymer-single-crystal-immobilized 6 and 15 nm diameter gold nanoparticles (AuNPs) using atom transfer radical polymerization. JNPs with bicompartment polymer brushes, such as poly(ethylene oxide) (PEO)/poly(methyl methacrylate), PEO/poly(tert-butyl acrylate), and PEO/poly(acrylic acid), were synthesized. The grafting densities can be carefully controlled. The Janus feature of these particles was confirmed using both platinum nanoparticle decoration and UV/Vis spectroscopy analysis. The surface plasmon resonance absorbance of Janus particles exhibited a blue shift compared with that of symmetric AuNPs with either homopolymer or mixed polymer brushes. This work demonstrated that using polymer single crystal as the templates, small size (<20 nm diameter) JNPs having bicompartment polymer brushes can be readily obtained. The ability to tune grafting density and molecular weight of polymer brushes can lead to controlled particle amphiphilicity.     

Optical tweezers to measure the interaction between poly(acrylic acid) brushes

Optical tweezers are employed to measure the forces of interaction within single pairs of poly(acrylic acid) (PAA) grafted colloids with an extraordinary resolution of ±0.5 pN. Parameters varied are the concentration and valency of the counterions (KCl, CaCl₂) of the surrounding medium as well as its pH. The data are quantitatively described by a recently published model of Jusufi et al. [Colloid Polym Sci 2004; 282:910] for spherical polyelectrolyte brushes which takes into account the entropic effect of the counterions. For the scaling of the brush height a power law is found having an exponent of 0.25 ± 0.02 which ranges between the values expected for spherical and planar brushes. From the model the ionic concentration inside the brush is estimated in reasonable agreement with the literature.     

Dispersion of polymer-grafted magnetic nanoparticles in homopolymers and block copolymers

The dispersion of magnetic nanoparticles (NPs) in homopolymer poly(methyl methacrylate) (PMMA) and block copolymer poly(styrene-b-methyl methacrylate) (PS-b-PMMA) films is investigated by TEM and AFM. The magnetite (Fe₃O₄) NPs are grafted with PMMA brushes with molecular weights from M = 2.7 to 35.7 kg/mol. Whereas a uniform dispersion of NPs with the longest brush is obtained in a PMMA matrix (P = 37 and 77 kg/mol), NPs with shorter brushes are found to aggregate. This behavior is attributed to wet and dry brush theory, respectively. Upon mixing NPs with the shortest brush in PS-b-PMMA, as-cast and annealed films show a uniform dispersion at 1 wt%. However, at 10 wt%, PS-b-PMMA remains disordered upon annealing and the NPs aggregate into 22 nm domains, which is greater than the domain size of the PMMA lamellae, 18 nm. For the longest brush length, the NPs aggregate into domains that are much larger than the lamellae and are encapsulated by PS-b-PMMA which form an onion-ring morphology. Using a multi-component Flory-Huggins theory, the concentrations at which the NPs are expected to phase separate in solution are calculated and found to be in good agreement with experimental observations of aggregation.     

Ordering of Polystyrene Nanoparticles on Substrates Pre-Coated with Different Polyelectrolyte Architectures

Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)₂, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)₂ and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)₂. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate.     

Size and Shape Dependence on Pt Nanoparticles for the Methylcyclopentane/Hydrogen Ring Opening/Ring Enlargement Reaction

Abstract  

Monodisperse Pt nanoparticles (NPs) with well-controlled sizes in the range between 1.5 and 10.8 nm, and shapes of octahedron, cube, truncated octahedron and spheres (~6 nm) were synthesized employing the polyol reduction strategy with polyvinylpyrrolidone (PVP) as the capping agent. We characterized the as-synthesized Pt nanoparticles using transmission electron microscopy (TEM), high resolution TEM, sum frequency generation vibrational spectroscopy (SFGVS) using ethylene/H₂ reaction as the surface probe, and the catalytic ethylene/H₂ reaction by means of measuring surface concentration of Pt. The nanoparticles were supported in mesoporous silica (SBA-15 or MCF-17), and their catalytic reactivity was evaluated for the methylcyclopentane (MCP)/H₂ ring opening/ring enlargement reaction using 10 torr MCP and 50 torr H₂ at temperatures between 160 and 300 °C. We found a strong correlation between the particle shape and the catalytic activity and product distribution for the MCP/H₂ reaction on Pt. At temperatures below 240 °C, 6.3 nm Pt octahedra yielded hexane, 6.2 nm Pt truncated octahedra and 5.2 nm Pt spheres produced 2-methylpentane. In contrast, 6.8 nm Pt cubes led to the formation of cracking products (i.e. C₁–C₅) under similar conditions. We also detected a weak size dependence of the catalytic activity and selectivity for the MCP/H₂ reaction on Pt. 1.5 nm Pt particles produced 2-methylpentane for the whole temperature range studied and the larger Pt NPs produced mainly benzene at temperatures above 240 °C.     

Solution combustion synthesis of La1−xSrxFe1−yCuyO3±w (x=0, 0.2; y=0, 0.2) perovskite nanoparticles: Conventional vs. microwaves ignition

La_1−xSr_xFe_1−yCu_yO_3±w (x=0, 0.2; y=0, 0.2) nanoparticles have been prepared by solution combustion synthesis exploiting both conventional and microwave heating in the ignition of the self-sustaining reactions. Interaction of microwaves with the reaction mixture allowed significant reduction of the ignition time according to the dielectric properties of the precursor gels, which have been measured at room temperature in the 0.5–3 GHz frequency range. Both the ignition strategies led to the preparation of crystalline single-phase products without affecting particles morphology. The ignition technique influenced only the average particles size with those prepared by microwaves-ignition, possessing typically larger dimension, as a probable consequence of the higher temperatures reached due to microwave absorbing products. Perfectly crystallised nanoparticles were obtained after combustion syntheses and calcination at 600 °C for 3 h in the particle size range between 20 and 80 nm dependently upon the heating source and the dopant level.     

Effects of annealing on the structural and magnetic properties of flame spray pyrolyzed MnFe2O4 nanoparticles

In this study, manganese ferrite (MnFe₂O₄) nanoparticles were produced through flame spray pyrolysis (FSP). To investigate the effects of heat treatment, the nanoparticles were annealed between 400 and 650°C for 4 h in air in a comparative manner. The structural, chemical, morphological, and magnetic properties of the nanoparticles were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM), respectively. The XRD results showed that the nanoparticles synthesized by the FSP method exhibited the MnFe₂O₄ spinel ferrite structure. The annealing process led to the decomposition of MnFe₂O₄ into various phases. According to the morphological analysis, the as-synthesized particles were hemispherical–cubic in shape and had an average particle size of less than 100 nm. In addition, the chemical bond structures of the nanoparticles were confirmed in detail by XPS elemental analysis. The highest saturation magnetization was recorded as 33.50 emu/g for the as-produced nanoparticles. The saturation magnetization of the nanoparticles decreased with increasing annealing temperature, while coercivity increased.     

Chemical synthesis of TiO2 nanoparticles and their inclusion in Ni–P electroless coatings

The work addresses the preparation of Ni3P3TiO₂ nanocomposite coatings on mild steel substrate by the electroless technique. Nanosized TiO₂ particles were first synthesized by the precipitation method and then were codeposited (4 g/l) into the Ni3P matrix using alkaline hypophosphite reduced EL bath. The surface morphology, particle size, elemental composition and phase analysis of as-synthesized TiO₂ nanoparticles and the coatings were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). Coatings with 20 µm thickness were heat treated at 400 °C for 1 h in argon atmosphere. The morphology, microhardness, wear resistance and friction coefficient characteristics (ball on disc) of electroless Ni3P3TiO₂ nanocomposite coatings were determined and compared with Ni3P coatings. The results show that as-synthesized TiO₂ nanoparticles are spherical in shape with a size of about12 nm. After heat treatment, the microhardness and wear resistance of the coatings are improved significantly. Superior microhardness and wear resistance are observed for Ni3P3TiO₂ nanocomposite coatings over Ni3P coatings.     

Improvement of (BH)max in Ba-hexaferrite doped with La and Co

In this work we produce Ba-hexaferrite nanoparticles by the ionic coordination reaction method and study the influence of La and Co ions on the magnetic properties of Ba_0.7La_0.3Fe_12-xCo_xO₁₉ for x = (0.0, 0.25, 0.50, 0.75 and 1.0) nanoparticles. The crystalline and morphological properties were studied by X-ray diffraction and scanning electron microscopy techniques. The magnetic properties of samples were studied in a vibrating sample magnetometer under an applied field of ±6 T. The Fe occupancy in the three octahedral (12k, 2a, and 4f₂), one tetrahedral (4f₁) and one trigonal bipyramidal (2b) sites was studied by Mössbauer spectroscopy. The samples are single domain nanoparticles with crystallite sizes in the range 71.5-50.1 nm, decreasing with the Co doping. The results suggest that the sample with x = 0.25 had the largest (BH)_max of 6.98 kJ/m³, this effect is mostly due to the occupancy of 4f₂ sites by Co²⁺. For x > 0.25, the Co²⁺ occupy mainly both the 4f₂ and 12k sites, the presence of oxygen vacancies is discussed.     

Preparation of polyacrylonitrile nanoparticles via dispersion polymerization of acrylonitrile using a poly(N-vinyl pyrrolidone)-cobalt complex in an aqueous system

Monodisperse spherical polyacrylonitrile (PAN) nanoparticles were successfully prepared for the first time by dispersion polymerization of acrylonitrile (AN) in water using well-defined poly(N-vinyl pyrrolidone) (PVP) that was end-capped by a cobalt(II) acetylacetonate (Co(acac)₂) complex (PVP-Co(acac)₂) as both a macroinitiator and a colloidal stabilizer. The well-defined PVP-Co(acac)₂ (M_n = 14,000 g/mol, PDI = 1.25) was synthesized by the bulk cobalt-mediated radical polymerization of N-vinyl pyrrolidone at 20 °C using 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) as an initiator and Co(acac)₂ as a regulating agent. The PVP macroradicals generated at 30 °C by the homolytic cleavage of the C–Co bonds in PVP-Co(acac)₂ initiated the dispersion polymerization of AN, as well as successfully stabilized the growing PAN particles. The average diameters of PAN nanoparticles synthesized with 20, 30, 40, and 50 wt% of PVP-Co(acac)₂ at 30 °C for 24 h were 263.5, 163.1, 157.3, and 143.5 nm, respectively. The PAN nanoparticles had a slightly crumpled spherical appearance, and the degree of crystallinity of the PAN nanoparticles prepared using 30 wt% of PVP-Co(acac)₂ was 31.2%. The mol% of VP units in the PAN nanoparticles was about 6 mol%, and the PVP chains were present on the surface of the PAN nanoparticles as a stabilizing layer. The PVP hairy chains could successfully stabilize very small Ag nanoparticles on the surface of the PAN nanoparticles.     

Heat capacity of nanocrystalline Yb2O3

A study of the structural, Raman scattering and thermodynamic properties of a nanocrystalline ceramic rare earth oxide Yb₂O₃ and its bulk counterpart is reported. The nanosized sample was obtained by mechanical milling of bulk Yb₂O₃ (99.998%, high purity powder). The Rietveld analysis of the X-ray diffraction data indicates the presence of nanoparticles with a mean grain size of 12 ± 1 nm after 75 h of milling time. The crystallographic structure within nanoparticles is cubic Ia-3 and the lattice parameter a = 10.455 ± 0.002 Å. The nanocrystalline structure is confirmed by the evaluation of transmission electron microscopy images, showing a size distribution with a mean size D_TEM = 8 ± 2 nm. Measurements of the specific heat (2 K–300 K) reveal an excess contribution respect to the unmilled (bulk) compound in the high temperature region above 70 K. At lower temperatures the results are consistent with a drastic change of the antiferromagnetic contribution (ordered below T_N = 2.2 K) as a result of the magnetic disorder arising from the size reduction process. The specific heat above T_N for the bulk and nanocrystalline samples are explained by the interplay among the phonon contribution, crystalline field and the presence of anharmonic effects. In the nanocrystalline state, broadening and shifts of the contribution of phonon modes to the Raman spectra, and a further reinforcement of the anharmonic contribution are found.     

Electrophoretic deposition of ZrB2 coatings in NaCl-KCl-AlF3 melt containing synthesized ZrB2 nanoparticles

A novel method for preparation of ZrB₂ coatings has been proposed by combination of molten salt synthesis of ZrB₂ nanoparticles and subsequent electrophoretic deposition of the as-synthesized ZrB₂ nanoparticles in the same molten system in this paper. Nanoscale ZrB₂ particles have been produced by borothermal reduction of ZrO₂ in NaCl-KCl-AlF₃ melt at 980°C. Then electrophoretic deposition of the as-synthesized ZrB₂ nanoparticles has been achieved in the resulting molten suspension at a reduced temperature of 900°C, yielding relatively dense ZrB₂ coatings on graphite substrates with a thickness of around 25 μm. Moreover, the effect of different cell voltages ranging from 0.8 V to 1.4 V (i.e., electric field 0.4–0.7 V/cm) on the prepared ZrB₂ coatings has been investigated. Finally, during the tests at 600°C–800°C in air, ZrB₂ coatings deposited at a cell voltage of 1.2 V have exhibited good high-temperature oxidation resistance.     

Ionic Liquid-assisted Synthesis of Polyaniline/Gold Nanocomposite and Its Biocatalytic Application

In this report, a novel chemical synthesis of polyaniline/gold nanocomposite is explored using ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate. The direct chemical synthesis of polyaniline/gold nanocomposite was initiated via the spontaneous oxidation of aniline by AuCl₄ ⁻ in IL. A nearly uniform dispersion of polyaniline/Au particles with a diameter of 450 ± 80 nm was produced by this method, which indicates that this method is more suitable for controlling particle dimensions. It was also found that the electrical conductivity of the polyaniline/gold nanocomposite was more than 100 times higher than that of the pure polyaniline nanoparticles. The polyaniline/gold nanocomposite displays superior function in the biocatalytic activation of microperoxidase-11 because of the high surface area of the assembly and the enhanced charge transport properties of the composite material. We also report the possible application of polyaniline/gold nanocomposite as a H₂O₂ biosensor.     

Antibacterial and photocatalytic behaviour of green synthesis of Zn0.95Ag0.05O nanoparticles using herbal medicine extract

The present work aimed to synthesize Zn_0.95Ag_0.05O (ZnAgO) nanoparticles using rosemary leaf extracts as a green chemistry method. The characterization of Ag-doped ZnO nanoparticles was performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet–visible spectrophotometry (UV–visible). The XRD, FTIR, and UV–visible spectra confirmed the formation of the presence of hexagonal ZnAgO nanoparticles. FESEM micrograph shows that the nanoparticles have been distributed homogeneously and uniformly. The morphology of ZnAgO nanoparticles is quasi-spherical configuration. Also, the mean particle size is in the range of 22–40 nm. The photocatalytic degradation of methylene blue in the presence of Ag-doped ZnO nanoparticles is nearly 98.5% after exposing 100 min. The ultraviolet lamp was used as the light source for photocatalyst degradation. The disc diffusion method was chosen to study the antibacterial activity of as-synthesized ZnAgO nanoparticles. Antibacterial activity of Zn_0.95Ag_0.05O nanoparticles against Staphylococcus aureus and Escherichia coli revealed that the as-synthesized ZnAgO nanoparticles were efficient in inhibition of bacterial growth.     

A novel combustion fuel for the synthesis of nanocrystalline ZnAl2O4 particles based on the thermodynamic correlations and their structural and optical studies

ZnAl₂O₄ nanocrystalline particles were prepared using the solution combustion method using a new combustion fuel, Leucine. The prepared samples' structural, microstructural–elemental composition, and optical characteristics were investigated using XRD, SEM-EDS, and UV–Visible spectroscopy. As-synthesized ZnAl₂O₄ nanoparticles are polycrystalline, with no secondary phases, and crystallized in a cubic - spinel structure. The polycrystalline nature of the prepared sample is due to the exothermicity of fuel and oxidizer, which demonstrate that the fuel utilized (Leucine) provided adequate energy for the production of nanoparticles in their as-synthesized form, as supported by adiabatic temperature through thermodynamic calculations. The thermodynamic calculations also include a universal method to estimate the specific heat capacity at constant pressure. Furthermore, even after 2 h of calcination at 600 °C, ZnAl₂O₄ exhibits a single phase with no secondary phases, indicating the material stability and single-phase nature. The crystallinity of ZnAl₂O₄ nanoparticles was observed to increase with increasing annealing temperature. SEM micrographs of as-synthesized samples exhibit the formation of dense particles, voids, and pores in the as-synthesized sample. In addition, tiny aggregates were detected on the surface of more prominent clusters, which reduced as the calcination progressed. In addition, calcined samples exhibit a greater optical reflectance than as-synthesized samples. Tauc's graphs were used to compute the optical energy bandgap. The calculated energy band gap is redshifted to that of the bulk material. The bandgap energy decreases upon calcination, suggesting that the prepared materials have a larger crystallite size or more crystallinity. Correlations were found between the T_ad, and the structural and optical properties of the prepared samples. The findings suggest that Leucine could be used as a novel combustion fuel to produce crystalline ZnAl₂O₄ nanoparticles in their as-synthesis form.