Solution Combustion Method Research Articles

Up-Conversion Luminescence in TbAl3(BO3)4: Yb3+ Syntesized by Solution Combustion Method

Up-Conversion Luminescence in TbAl3(BO3)4: Yb3+ Syntesized by Solution Combustion Method

Carbon dots encapsulated in (YGd)2O3:Eu3+ nanophosphors for thermal sensing, advanced forensic and information security applications

The outstanding optical characteristics of carbon dots (CDs) make them an extremely promising class of multifunctional nanomaterials based on carbon. The incorporation of hydrothermally prepared Aloe vera carbon dots (AVCDs) into europium doped yttrium gadolinium ((YGd)2O3:Eu3+) mixed oxide nanophosphors ((YGO):Eu3+ NPs) synthesized through the solution combustion (SC) method. The resulting (YGO):Eu3+@AVCDs nanocomposite (NCs) demonstrates a broad excitation band, with the intense peak at ∼395 nm, aligning with the emission wavelength (350–420 nm) of n-UV LED chips. Notably, the (YGO):Eu3+@AVCDs (5 wt %) NCs exhibits a 4 fold increase in photoluminescence (PL) intensity compared to (YGO):7Eu3+, attributed to the fluorescence resonance energy transfer (FRET) between AVCDs and Eu3+ ions. Remarkably, even at an elevated temperature of 423 K, the thermal stability of (YGO):Eu3+@AVCDs (5 wt %) remains exceptional, retaining 88.31 % of its initial luminescence intensity. The internal quantum efficiency (IQE) is measured at a notable 74.16 %, while the optimized composite achieves a remarkable color purity of 99.59 %. Latent fingerprints (LFPs) are effectively developed on different surfaces using the optimized NCs via a simple powder dusting technique, and these fingerprints (FPs) revealed under 365 nm UV light. The study also examines various pore parameter namely size, shape, number, position, type, and inter-distance. Moreover, a transparent anti-counterfeiting (AC) ink is fabricated using optimized NCs providing effective AC features through its red emission under 365 nm UV light. This study not only offers solutions for overcoming the self-quenching effect of CDs but also underscores the potential applications in white light emitting diodes (w-LEDs), latent fingerprints, lip prints (LPs), and anti-counterfeiting.

Electrochemical properties of spinel LiMn1.92-xCu0.08NixO4 cathode material prepared by a solution combustion method

A series of Ni-Cu co-doped spinel LiMn1.92-xCu0.08NixO4 cathode materials were successfully synthesized by a solution combustion method. X-ray diffraction (XRD) spectra showed that all the as-prepared LiMn1.92-xCu0.08NixO4 samples belong to spinel LiMn2O4 structure without any impurity phase. Scanning electron microscopy (SEM) showed that the particle size of the samples decreased with the increase of Ni-doping amount, and the crystallinity increased gradually. The galvanostatic charge/discharge tests results showed that the LiMn1.86Cu0.08Ni0.06O4 sample shows excellent rate performance and cyclic stability. At room temperature and 1 C, the initial discharge specific capacity of LiMn1.86Cu0.08Ni0.06O4 was 103.4 mAh g-1, and the capacity retention rate of 67.80% was obtained after 1000 cycles, which was higher than 49.60% of LiMn2O4. Even at high current densities of 5 C and 10 C, the good capacity retention rates of 73.55% and 67.29% for LiMn1.86Cu0.08Ni0.06O4 sample were obtained after 1000 cycles, respectively.

A comprehensive study of dielectric, modulus, impedance, and conductivity of SrCeO3 synthesized by the combustion method

AbstractIn this work, perovskite oxide SrCeO3 was synthesized using the solution combustion method (SCM). Synthesized samples have been characterized using X‐ray diffraction (XRD), Raman, ultra violet (UV)–visible spectroscopy, and scanning electron microscopy (SEM) techniques. The XRD and Rietveld refinement has confirmed the orthorhombic structure with space group Pnma. The average grain size of this ceramic sample is 1.2 µm. The dielectric constant, dissipation factor, modulus, impedance, and alternating current (AC) and direct current (DC) conductivities were analyzed in the temperature range RT to 600°C and frequency range 20 Hz–2 MHz. Further, it was observed that the role of grain boundaries in dielectric and electrical properties is significant, at low temperatures. The origin of the dielectric relaxation and conduction process is the same. The activation energy for DC conduction (Edc) was found to be .79 eV. Electrical conduction/relaxation is assigned to the diffusion of doubly ionized oxygen (Vo··). The value of DC conductivity (1.2 × 10−3 Ω−1 cm−1 at 600°C) and activation energy of .79 eV is very close to the values reported for doped CeO2‐based oxide ion conductors for SOFCs. This study has demonstrated that SrCeO3 can be an alternative candidate for the oxide ion conductor electrolyte application and the potential to be used as a thermally stable capacitor application for microwave dielectric applications.

Evaluation of TL and OSL signals of MgB4O7:Tm,Li prepared by the solution combustion method

Magnesium tetraborate (MgB4O7) doped with rare-earth elements is recognized for its suitability in thermoluminescence (TL) dosimetry due to its low effective atomic number (Zeff = 8.4) and the potential applications in neutron dosimetry. The study investigates the luminescent (TL and OSL) properties of MgB4O7 doped with thulium (Tm3+) and lithium (Li+). Samples were synthesized using the solution combustion method and TL and OSL responses were evaluated using a spectrometer and an automated OSL/TL reader. The emission lines of Tm3+ are consistent with previous literature, with Li+ enhancing TL and OSL responses. TL emission spectra unveil distinct bands corresponding to [Tm3+]* transitions. The electron paramagnetic resonance (EPR) spectroscopy analysis carried out in unirradiated, irradiated and annealed samples.The results show that the signals corresponding to BO32− and O2− are seen upon irradiation and disappear after annealing at 200 °C, indicating the participation of these centers in the TL process. The results show that the TL response of MgB4O7:Tm,Li is much more sensitive to gamma radiation than MgB4O7:Tm, with a minimum detectable value of 0.084 mGy and a linear response with dose for the range studied, from 0 to 500 mGy, with R2 of 0.998.

Effect of synthesis method on structural and magnetic properties of La0.7Ca0.2Ba0.1MnO3

Abstract We study the effect of the synthesis method on the structural and magnetic properties of La0.7Ca0.2Ba0.1Mn03. The samples were synthesized by coprecipitation and solution combustion methods. X-ray diffraction and scanning electron microscopy were performed to investigate the crystallographic structure, showing that both methods produced La0.7Ca0.2Ba0.1Mn03 monophasic samples. From magnetization measurements a second-order, ferromagnetic to paramagnetic, phase transition was observed. The Curie temperature is found to be 272 K for the sample obtained by coprecipitation and 283 K for the sample obtained by solution combustion. There is a small magnetic hysteresis for both samples. The magnetocaloric parameters were obtained using a phenomenological model; the magnetic entropy change and relative cooling power factor are higher in the sample synthesized by combustion.

The structural, magnetic and electrical properties of zinc-doped orthorhombic calcium ferrite nanoparticles: Memory device and high-frequency applications

Calcium ferrite nanoparticles (NPs), doped with Zinc in the range of 10–50[Formula: see text]mol%, were synthesized through a solution combustion method using citrus Limon extract as a reducing agent, followed by calcination at 500∘C. The synthesized samples are characterized with different techniques. Bragg reflections confirmed the formation of orthorhombic crystal structure. The shifting of the peak toward higher angle side is observed with increase in the dopant concentration. The surface exhibited irregular shapes and sized NPs with pores and voids in their morphology. The direct energy band gap increases from 2.91 to 2.97[Formula: see text]eV with increase in Zinc concentration. Further, magnetic and dielectric properties were carried out to know their importance in the high-frequency devices. Magnetic parameters, such as saturation magnetization (Ms), remanence (Mr), and coercivity (Hc) values, are discussed. Ms, Mr and Hc increase with increase in dopant concentration upto 30[Formula: see text]mol% and thereafter decreases. The dielectric studies revealed a decreasing dielectric constant from 2.98 to 1.84 as the dopant concentration increased. These findings suggest the potential use of these samples in memory devices and high-frequency applications.

Insights into Co and Fe-doping effects of mesoporous CeO2 catalysts for dry reforming of glycerol to syngas production

The dry reforming of glycerol (GDR) is one of the alternatives for syngas production by utilizing biodiesel byproduct glycerol and CO2. The development of highly active and stable catalyst is significantly important to achieve GDR process, and the current work provides insights into Co and Fe-doping effects of mesoporous CeO2 (CoFeCe) catalysts synthesized by the colloidal solution combustion method. The prepared catalysts presented the uniform mesoporous structure, the doping of Co and Fe metals resulted in stronger metal-support interaction. The GDR experimental data were compared with the non-stoichiometric thermodynamic equilibrium values. The conversions of glycerol and CO2 were increased with increasing the reaction temperatures due to the endothermic GDR reaction, and the H2/CO produced in syngas was in the range of 0.7–1.4. Due to the improvement of Co and Fe metals in the mesoporous structure of CeO2 catalyst, the 7CoFeCe catalyst exhibited excellent and stable GDR performance and no significant signs of deactivation were observed during 76 h test, and the results indicated that the enhanced interaction and high dispersion of Co and Fe in mesoporous CeO2 catalyst could inhibit carbon formation and promote GDR reaction.

NanoGuard: Antibacterial marvels of strontium titanate – Synthesis, characterization, and multifunctional insights

This study presents a comprehensive exploration into the synthesis and multifaceted characterization of strontium titanate (ST) nanopowder via the solution combustion method. The investigation delves into the photoluminescent properties, electrochemical behaviors assessed through potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), as well as antibacterial characteristics of the synthesized nanoproduct. Through meticulous analysis involving powder X-ray diffraction (PXRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and UV–visible spectroscopy (UV–vis), ST nanoparticles revealed intriguing features. PXRD unveiled a cubic crystal structure with a crystallite size of ∼ 11 nm, showcasing a crystallinity of 89.23. FESEM, UV–visible spectroscopy, and FT-IR studies uncovered irregularities in size, band gap properties, and the formation of M−O bonds within ST, with an Eg value of ∼ 3.0 eV. Photoluminescence investigations highlighted oxygen deficiencies within the ST material. Furthermore, corrosion inhibition efficiency was evaluated, demonstrating a maximum of 81.9 % at a concentration of 400 ppm, while antibacterial studies exhibited promising results against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, with zone of inhibitions (ZOI) measuring 8.00 ± 0.250 mm and 9.00 ± 0.000 mm, respectively. These findings collectively underscore the diverse potential applications of ST nanoparticles and offer valuable insights into their structural, optical, electrochemical, and antimicrobial properties.

A Flexible Nickel-Oxide-Based RRAM Device Prepared Using the Solution Combustion Method

Binary metal oxide materials, such as nickel oxide, are widely used in flexible resistive variable memory devices due to advantages such as their easily controllable material composition, simple structural composition, and good compatibility between manufacturing processes and complementary metal oxide processes. In this work, a solution combustion method was employed to prepare NiOx thin films for use as a resistive switching layer of resistance random-access memory. The formation temperature of the NiOx layer in the RRAM device was kept as low as 175 °C, making the device compatible with flexible substrates. With polyethylene naphthalenediate as the substrate, the NiOx-based RRAM exhibited obvious bipolar resistance-switching properties, superb bending resistance, and good stability. Through theoretical fitting and structural characterization, the conduction mechanisms were attributed to the combination of the space-charge-limited current and Ohmic mechanisms, while the valence change mechanism was determined to be the resistive switching mechanism. This study demonstrates a low-temperature and scalable approach to constructing NiOx-based RRAM devices on flexible substrates.

Solution Combustion Synthesis of Ce‐based Composite Oxygen Carriers for Chemical Looping Reforming of Methane

AbstractEfficient activation and the conversion of methane to value‐added products have long attracted interest. Chemical looping reforming has become a competitive technology to transform methane into syngas that can act as raw material for various chemicals. In this paper, the methane chemical looping reforming reactivity of the Ce−Co composite oxygen carriers fabricated with different preparation methods, including solution combustion, ball‐milling, hydrothermal, and co‐precipitation method, are investigated on a fixed‐bed. Various bulk/surface characterizations (TEM, XRD, BET, XPS, Raman, etc.) were applied to reveal the effect of preparation methods on the properties of these oxygen carriers. The results indicate that the oxygen carrier prepared by the solution combustion method exhibits excellent methane conversion, high syngas yield, and desirable H2/CO ratio, as well as stable regenerability because of its relatively small crystal size, large specific surface area, high oxygen vacancy concentration and Ce3+/Ce4+ ratio. This work may be helpful in the preparation of highly active and stable oxygen carriers for chemical looping reforming reaction of methane.

Sr0.99Zr(PO4)2:0.01Eu3+ ceramic glass for photoluminescence applications

This paper reports the first-time synthesis of Sr0.99Zr(PO4)2:0.01Eu3+ nanophosphor via solution combustion method using glycine as fuel at a fuel-to-oxidizer ratio of 1:1. The PXRD pattern confirmed the formation of the desired phase, while the Scherrer calculation revealed an average particle size of approximately 60 nm. Scanning electron microscopy (SEM) further corroborated the particle size, estimating it around 75 nm. The material exhibited a characteristic mesoporous structure, a hallmark of the solution combustion synthesis technique. Photoluminescence (PL) spectroscopy revealed two intense emission peaks at 590 nm and 615 nm, attributed to Eu3+ ions, suggesting potential applications in LED technology. CIE coordinates indicated emission close to the white region defined by the NTSC standard

Display and energy storage applications of copper doped nanoceria

In the current study CeO2: Cu2+ (0–11 mol%) NPs were synthesized by Aloevera mediated solution combustion method followed by calcination. The synthesized samples were described and their multifunctional characteristics, including photoluminescence, sensor, and supercapacitor features were covered thoroughly. Bragg reflections confirmed single-phased CeO2: Cu2+ NPs with cubic spinel structure belonging to space group Pm3m(221). Crystal size was estimated using both the Scherrer and W-H plot method. The energy gap was computed from the Wood-Taucs relation. The crystallite size increases whereas the energy band gap increases with an increase in dopant concentration. The photoluminescence emission peaks of CeO2:Cu2+ (1–11 mol%) NPs, CIE, and CCT λex= 340 nm unambiguously show that the current nanophosphor might be a promising nanophosphor material for white and blue LEDs. The Cyclic voltammetry analysis was performed on as obtained CeO2: Cu2+ NPs for oxidation and redox peaks. EIS revealed that ion transport kinetics and super-capacitance values were obtained from GCD analysis. Specific capacitance values are found to be in the range 18 to 61 F/g for CeO2: Cu2+ 1 to 11 mol % NPs respectively which are in good agreement with the values obtained from CV analysis. Thus, the present synthesized material might find applications in the field of display technology and energy storage materials.

Effect of nickel doping on magnetic and dielectric properties of orthorhombic calcium ferrite nanoparticles

Nickel (10∼50 mol%) doped calcium ferrite nanoparticles (NPs) are synthesized by the solution combustion method using lemon juice extract as a reducing agent, followed by calcination at 500°C. The calcined samples are characterized with different techniques. The Bragg reflections of Nickel doping confirm the formation of a single orthorhombic calcium ferrite phase. The crystallite size is estimated using both Scherrer's and the W-H plot method. The surface morphology consists of irregular size and shaped agglomerated NPs along with pores and voids. A blueshift and a broad absorption spectrum is observed with an increase in the direct energy band gap. The direct energy band gap estimated from Wood and Tauc's relationship was found to be 2.91∼2.97 eV with an increase in dopant concentration. The magnetic analysis provided values for saturation magnetization (Ms), remanence (Mr), and coercivity (Hc), while dielectric studies demonstrated a dielectric constant of 2.81, 2.14, and 1.67 with increasing dopant concentration. The variation of dielectric properties of the sample as a function of frequency in the range 0.1∼20 MHz has been studied at room temperature. The dielectric properties of CaFe2O4: Ni (1∼9 mol%) NPs clearly indicate that there is a more pronounced dispersion at lower frequencies, gradually reaching saturation as the frequency increases. The dielectric loss was found to decrease from 4.62, 3.22, and 2.32 with an increase in Ni2+ substitution (10, 30, and 50 mol%) respectively. These results indicate the suitability of these samples for applications in memory devices and high-frequency applications.

Dual p-n Z-scheme heterostructure boosted superior photoreduction CO2 to CO, CH4 and C2H4 in In2S3/MnO2/BiOCl photocatalyst

The creation of a Z-scheme heterojunction is a sophisticated strategy to enhance photocatalytic efficiency. In our study, we synthesized an In2S3/MnO2/BiOCl dual Z-scheme heterostructure by growing BiOCl nanoplates on the sheets of In2S3 nanoflowers, situated on the surface of MnO2 nanowires. This synthesis involved a combination of hydrothermal and solution combustion methods. Experiments and density functional theory (DFT) calculations demonstrated that the In2S3/MnO2/BiOCl composite exhibited notable photo reduction performance and photocatalytic stability. This was attributed to the pivotal roles of BiOCl and MnO2 in the composite, acting as auxiliaries to enhance the electronic structure and facilitate the adsorption/activation capacity of CO2 and H2O. The yield rates of CO, CH4, and C2H4 over In2S3/MnO2/BiOCl as the catalyst were 3.94, 5.5, and 3.64 times higher than those of pure In2S3, respectively. Photoelectrochemical analysis revealed that the dual Z-scheme heterostructure, with its oxygen vacancies and large surface area, enhanced CO2 absorption and active sites on the nanoflower/nanowire intersurfaces. Consequently, the dual Z-scheme charge transfer pathway provided efficient channels for boosting electron transfer and charge separation, resulting in high C2H4, CH4, and CO yields of formed and exihibits an promising photoreduction rate of CO2 to CO (51.2 µmol/g.h), CH4 (42.4 µmol/g.h) and C2H4 (63.2 µmol/g.h), respectively. DFT, in situ Diffuse reflectance infrared fourier transform spectroscopy, and temperature-programmed desorption tests were employed to verify the intermediates pathway. The study proposed a potential photocatalytic mechanism based on these findings.

High stable NiCoAl catalyst prepared by combustion method for the hydrodeoxygenation of lignin-derived phenolic compounds: Effect of calcination temperature

The hydrodeoxygenation of lignin-derived phenolic compounds holds great promise for biomass-derived liquid fuel production. However, achieving a consistently high cyclohexane yield poses a formidable challenge. In this study, NiCoAl catalysts were successfully synthesized using the solution combustion method for the hydrodeoxygenation of lignin-oil. The impact of calcination temperature on the preparation of NiCoAl catalysts was investigated. The results indicate that the selectivity of cyclohexane exhibits an initial increase followed by a decrease as the calcination temperature rises. Notably, the NiCoAl-600 catalyst reached 99.99% guaiacol conversion, with the highest selectivity of cyclohexane (97.96%) achieved. Characterization results demonstrate that the transition of the spinel structure from normal to inverse with rising calcination temperature. Moreover, the catalyst particle size initially decreases and then increases, while the oxygen vacancy concentration in the catalyst increases. It was found that these properties contribute to a better hydrodeoxygenation performances of guaiacol and other phenolic compounds over non-noble NiCoAl catalyst. Possible reaction pathway and mechanism are proposed and discussed. Additionally, the spinel-structured NiCoAl-600 catalyst has good thermal stability, ensuring potential application in the upgrading of lignin-oil.

Solution combustion method for synthesis of ZnO NPs from Syzygium hemisphericum bark extract and a comparative analysis of the same with the crude bark extract for biomedical applications

Solution combustion method for synthesis of ZnO NPs from Syzygium hemisphericum bark extract and a comparative analysis of the same with the crude bark extract for biomedical applications

Green synthesis of aluminium-substituted calcium hexaferrite nanoparticles for high-frequency applications

As the first of their kind, Al3＋-substituted calcium hexaferrite (CaAlxFe12−xO19 (x=0, 1, 3, 5 and 7)) nanoparticles (NPs) were synthesized via a facile, economical, eco-friendly lemon juice extract-mediated green solution combustion method. The samples were calcined, followed by characterization. The Bragg reflections confirm the formation of a single-phase magnetoplumbite (M)-type hexaferrite crystal structure. No other impurity or mixed phases are observed even after the substitution of Al3＋ in the host matrix. The crystallite size decreases from 17 to 11 nm with an increase in the substitution of Al3＋ ions. Surface morphological analysis shows the presence of agglomerated irregularly shaped NPs. The direct band gap estimated with Wood and Tauc’s relation decreases from 4.22 to 3.76 eV with an increase in the substitution of Al3＋ ions. These Al3＋-substituted calcium hexaferrite NPs are predicted to be useful in high-frequency applications based on structural, dielectric, and magnetic studies.

Chemical tuning of photo- and persistent luminescence of Cr3+-activated β-Ga2O3 by alloying with Al2O3 and In2O3

An effect of alloying of the monoclinic β-Ga2O3 with Al2O3 and In2O3 on the photoluminescent, thermoluminescent and persistent luminescent properties of Cr3+ ions has been comprehensively investigated. For this purpose, various series of Cr3+ and Ca2+ co-doped microcrystalline phosphors were synthesized by the solution combustion method, including pseudobinary compounds like (Ga-Al)2O3 with up to 20 % Al and (Ga-In)2O3 with up to 50 % In as well as pseudoternary compounds (Ga-Al-In)2O3 with balanced proportion of Al, Ga and In. The phase composition and crystal structure of the obtained materials were examined by X-ray powder diffraction technique. Detailed luminescence studies were conducted for the (Ga-Al)2O3 and (Ga-In)2O3 compounds which exhibited a single-phase monoclinic structure. Low-temperature and time-resolved photoluminescence investigations of the Cr-doped pseudobinary compounds unveiled several types of Cr3+ centres, attributed to the Al-, Ga- and In-centred octahedra in the studied alloys. The obtained results underscore the benefit of bandgap engineering through alteration in the host lattice chemical composition for efficient tuning of the thermoluminescent and persistent luminescent properties of the near-infrared-emitting β-Ga2O3:Cr based phosphors. Furthermore, it was demonstrated that modification of the chemical composition of the host lattice also adjusts the thermometric performance of the studied phosphors. Indeed, the specific sensitivity of the β-Ga2O3:Cr3+ decay time luminescence thermometer showed nearly twofold enhancement when the host lattice was alloyed with 30 % of In2O3.

Copper-Enhanced CO2 Electroreduction in SOECs.

The development of a Co-free and Ni-free electrocatalyst for carbon dioxide electrolysis would be a turning point for the large-scale commercialization of solid-oxide electrolysis cells (CO2-SOECs). Indeed, the demand for cobalt and nickel is expected to become critical by 2050 due to automotive electrification. Currently, the reference materials for CO2-SOEC electrodes are perovskite oxides containing Mn or Co (anodes) and Ni-YSZ cermets (cathodes). However, issues need to be addressed, such as structural degradation and/or carbon deposition at the cathode side, especially at high overpotentials. This work designs the 20 mol % replacement of iron by copper in La0.6Sr0.4FeO3-δ as a multipurpose electrode for CO2-SOECs. La0.6Sr0.4Fe0.8Cu0.2O3-δ (LSFCu) is synthesized by the solution combustion method, and iron partial substitution with copper is evaluated by X-ray powder diffraction with Rietveld refinement, X-ray photoelectron spectroscopy, thermogravimetric analyses, and electrical conductivity assessment. LSFCu is tested as the SOEC anode by measuring the area-specific resistance versus T and pO2. LSFCu structural, electrical, and electrocatalytic properties are also assessed in pure CO2 for the cathodic application. Finally, the proof of concept of a symmetric LSFCu-based CO2-SOEC is tested at 850 °C, revealing a current density value at 1.5 V of 1.22 A/cm2, which is remarkable when compared to similar Ni- or Co-containing systems.