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Pure Lanthanum Ferrite (LaFeO3) nanoparticles and Lanthanum Magnesium Ferrite (LaMgxFe1-xO3) nanocomposites have been prepared by the sol-gel auto-combustion method. The structural and morphological properties were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX) spectroscopy. Powder XRD studies revealed that the samples are pure orthorhombic perovskite crystals with a size of around 20-50 nm. The FT-IR spectra of pure and composites was confirmed the formation perovskite structure. It has been discovered that composites material functions as an electrode in supercapacitors after its electrical characteristics have been examined by galvanostatic charging and discharging (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) with a 2 M KOH electrolyte. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of double perovskite La 2 CrMnO 6 nanoparticles by auto-combustion route. • Preparation of La 2 CrMnO 6 /g-C 3 N 4 nanocomposites by ultrasonic-assisted co-precipitation method. • Higher photodegradation yield due to synergistic effect between La 2 CrMnO 6 and g-C 3 N 4. • La 2 CrMnO 6 /g-C 3 N 4 (80:20) nanocomposites showed 80.98 % removal of methyl orange (MO). • Photocatalytic mechanism in nanocomposite system for MO degradation was proposed. Constructing semiconductor materials based on layered graphitic carbon nitride (g-C 3 N 4) and metal oxides can help in extending the lifetime of charge carriers and aid in resolving the low number of active sites on their surface for light-driven processes. Herein, we initially designed La 2 CrMnO 6 nanostructures through trimesic acid-assisted auto-combustion route and subsequently, La 2 CrMnO 6 /g-C 3 N 4 nanocomposites were prepared by ultrasonic-assisted co-precipitation method with improved UV-catalytic performance. The shape, size distribution and various properties of nano-sized products were measured via diverse description systems of microscopic and spectroscopic. The photocatalytic performances of the La 2 CrMnO 6 nanoparticles and La 2 CrMnO 6 /g-C 3 N 4 nanocomposites were compared by degradation of artificial dyes under the UV-light region. Besides, the impacts of dye type, diverse weight percentages of g-C 3 N 4 :La 2 CrMnO 6 in composite, scavenger kind and dye solution concentration were studied on modifying ability of nano-catalyst utility. The outcomes manifested La 2 CrMnO 6 /g-C 3 N 4 (80:20) nanocomposites have the greatest efficiency, where the highest MO decomposition of 80.98 % was achieved at 10 ppm within 90 min of irradiation. Moreover, the feasible mechanism of MO elimination by UV catalytic purpose was considered. [ABSTRACT FROM AUTHOR]

Nanoscale SrAl2O4: Eu2+, Dy3+ with controllable size and morphology was synthesized by sol-gel auto-combustion method. The surface morphology and structural characterization were carried out with TEM and XRD. Optical properties were analyzed by comparing excitation spectra, emission spectra and afterglow decay of the nanoscale phosphor with that of the bulk phosphor. The results showed that citric acid acted as a soft template in the reaction system. The morphology and size changed clearly with pH value and sintering temperature. The crystallinity was affected by the quantity of citric acid. Both the nanoscale phosphors with different particle size and the bulk one have the strongest emission at 525 nm. But their strongest peaks in excitation spectra are very different from each other. The phosphorescence of nanoscale phosphor decays more rapidly than that of the bulk phosphor. [ABSTRACT FROM AUTHOR]

Nanoscale SrAl2O4: Eu2+, Dy3+ with controllable size and morphology was synthesized by sol-gel auto-combustion method. The surface morphology and structural characterization were carried out with TEM and XRD. Optical properties were analyzed by comparing excitation spectra, emission spectra and afterglow decay of the nanoscale phosphor with that of the bulk phosphor. The results showed that citric acid acted as a soft template in the reaction system. The morphology and size changed clearly with pH value and sintering temperature. The crystallinity was affected by the quantity of citric acid. Both the nanoscale phosphors with different particle size and the bulk one have the strongest emission at 525 nm. But their strongest peaks in excitation spectra are very different from each other. The phosphorescence of nanoscale phosphor decays more rapidly than that of the bulk phosphor. [ABSTRACT FROM AUTHOR]

The three-dimensional porous ceria (CeO 2) nanostructures and cobalt (Co) doped porous ceria with different cobalt contents (1 %, 2.5 %, 5 %, and 10 % wt%) were prepared by using the auto-combustion technique. Several characterization techniques, including ICP elemental analysis, XRD, DR UV-Vis, SEM, and TEM, were utilized to describe the fabricated products. The findings confirmed the incorporation of cobalt ions into the ceria framework. Furthermore, the light absorption property of cobalt-doped porous ceria samples was observed to be red-shifted, with the calculated bandgap decreasing from 3 to 2.1 eV for neat porous ceria and 10 % Co doped ceria, respectively. The photocatalytic efficiency of cobalt-doped porous CeO 2 was investigated in the decolourization of methyl green dye by utilizing visible light illumination. The photocatalytic data obtained revealed a remarkable increase in activity that is nearly three times greater than the un-doped ceria sample. Furthermore, the best performed cobalt-doped ceria sample was reusable until the fourth consecutive reaction without treatment. [ABSTRACT FROM AUTHOR]

In this work, for the first time, W-type barium ferrite nanostructures (BaFe 18 O 27 ) were synthesized by sol–gel auto combustion method. The role of the calcination temperature and the type of sugar were investigated on the basis of their morphology and the size of the particles. The obtained products were characterized by Electron microscopy (EM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and energy dispersive spectrometry (EDS) and vibrating sample magnetometer (VSM). Adsorptive desulfurization (ADS) is one of the most promising complementary and alternative methods. To evaluate the ADS reactivity over the W-ferrite, a series of ADS experiments with a model gasoline feedstock were performed using a fixed-bed reactor. The results of catalytic tests reveals that BaFe 18 O 27 nanoparticles have the potential to be used as a new absorptive for desulfurization of liquid fuels. 0.5 g BaFe 18 O 27 exhibited the highest ADS properties. This ferrite was successfully regenerated after calcining at 500 °C in air. [ABSTRACT FROM AUTHOR]

((1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3-(1-x)PZN-xPT) single crystals with perovskite structure near to the morphotropic phase boundary (MPB), x~0, 09, exhibit unusual large dielectric and piezoelectric constants. Preparation of PZN-PT ceramics with composition near to the MPB using conventional methods leads to ceramics with pyrochlore structure. In this paper, ((1 - x)Pb(Zn1/3Nb2/3)O3-xPbTiO3-PZN-xPT) powders with x = 0; 10 were synthetized by the combustion reaction method. CO(NH2)2, C2H5NO2, CO(NH2)2=C2H5NO2 y C4H16N6O2 were used as fuels. Results show that a maximum of 70% of perovskite phase was obtained using CO(NH2)2= C2H5NO2 (in relation 50=50). The afore mentioned phase is preserved when sintering the sample at 1000°C, during 4h on nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

• Auto-combustion route was optimized to obtain pure BiFeO 3 powder without calcination. • Magnetization of powders and composites originate from Fe 3 O 4 nanoparticles. • Auto-combustion synthesis of BiFeO 3 with glycine fuel forms Fe 3 O 4 as a by-product. • Dopants influence the properties in a more complex way than only by charge and size. • Y3+ and Zr4+ as dopants led to best improvement in electrical properties. Bismuth ferrite (BiFeO 3) powders were synthesized by auto-combustion method using glycine as a fuel. Doping ions of different valence were used to study the influence on electrical conductivity and ferroelectric properties. Powders were mixed and hot-pressed with α-PVDF to form flexible composite samples. Composites endured significantly higher electrical fields with lower leakage and retained the weak ferromagnetism present in powders. Dielectric properties were improved by doping with Zr4+, Y3+ and Ca2+ as well as the electrical resistivity. Flexible composites exhibited improved electrical resistivity and modified conduction mechanism. Relatively high magnetization of powders completely originates from magnetite particles formed during the combustion, while sintered samples exhibited typical antiferromagnetic behaviour. [ABSTRACT FROM AUTHOR]

The color-tunable GdCaAl 3 O 7 : RE3+ (RE = Eu, Tb, Eu@Tb) phosphors were synthesized via an ultrafast sol-gel auto-combustion synthesis method. The X-ray diffraction patterns confirmed the forming of GdCaAl 3 O 7 tetragonal phase, and the scanning electron microscopy images indicated that the obtained products presented honeycomb-like structure due to the gas releasing during the auto-combustion process. The luminescent properties, concentration quenching mechanism, energy transfer mechanism, luminescent dynamics, thermal stability and product practicability of GdCaAl 3 O 7 : RE3+ (RE = Tb, Eu, Eu@Tb) phosphors were investigated systematically. All the GdCaAl 3 O 7 : RE3+ products presented the characteristic emission of doped RE3+. Using GdCaAl 3 O 7 : 50% Tb3+@3.0% Eu3+ as yellow-emitting phosphors in combination with commercial BAM: Eu2+ blue-emitting phosphors and a NUV chip can successfully package a warm white LED device with high color rendering index (CRI, 86.3) and low correlated color temperature (CCT, 3348 K) that was very suitable for near-ultraviolet light-triggered indoor illumination. • Color-tunable phosphors were prepared by an ultrafast auto-combustion method. • Luminescent properties, dynamics and product practicability were investigated. • Energy transfer mechanism and concentration quenching effects were discussed. • Glaring warm white light with high CRI and low CCT was obtained. • Products were very suitable for near-ultraviolet light-triggered indoor illumination. [ABSTRACT FROM AUTHOR]

In this study, pure phase BiFeO 3 was prepared via a facile sol-gel auto-ignition route using water as a solvent. The influence of citric acid to metal nitrates molar ratio on physicochemical properties of BiFeO 3 was also investigated through FTIR, XRD, PL, UV, SEM, and BET analysis. The XRD of the prepared samples revealed the rhombohedral perovskite structures belong to space group R3c. In addition, the BFO2:1 sample showed the smallest crystallite size (42 nm) with the highest purity and recombination rate; while the BFO1:2 sample showed the lowest purity and electron charge recombination rate. The surface areas of the BFO1:1, BFO1:2, and BFO2:1 samples were 1.63, 2.13, and 1.84 m2/g, respectively. Moreover, the bandgaps were found to be 2.17, 2.11, and 2.21 eV for the prepared BFO1:1, BFO1:2, and BFO2:1, respectively. In addition, the appearance of a near-IR band around 814 cm−1 confirms the presence of Bi 2 Fe 4 O 9 byproduct in the BFO1:2 sample. Finally, SEM revealed that BFO2:1 sample was well-distributed and exhibited uniform morphology, referring to citric acid's ability to stabilize and disperse bismuth ferrite NPs. Furthermore, BFO1:2 sample showed enhanced photocatalytic activity in CR dye degradation than BFO1:1 and BFO2:1 samples, attributed by the increase in the surface area and minimized electron-hole recombination. This strategy eliminates the use of conventional organic solvents and provides an effortless and efficient way to prepare pure BiFeO 3 and BiFeO 3 /Bi 2 Fe 4 O 9 heterojunction nanocomposite that are potentially applicable for photocatalyst and in solar cell production. • Synthesis of pure phase BiFeO 3 and heterojunction nanocomposite BiFeO 3 /Bi 2 Fe 4 O 9 by sol-gel auto combustion route. • Citric acid is used as a fuel and stabilizer, and water is used as a solvent instead of an organic solvent. • Study the effect of citric acid to metal nitrates molar ratio on physicochemical properties of the synthesized samples. • The formation of nanocomposite between bismuth ferrite phases enhanced the photocatalytic degradation of CR. • The enhanced performance is associated with improved surface area and charge separation. [ABSTRACT FROM AUTHOR]

Abstract: In this experiment, nanocrystalline Y3Ba5Cu8O18 superconductor powder was prepared by citrate–nitrate auto-combustion reaction. A series of Y3Ba5Cu8O18 precursor gels with different citrate–nitrate ratio ranged from 0.3 to 1.0 have been prepared by varying the amount of citric acid added. The auto-combustion reaction during drying process transformed the precursor gels into ashes powder that upon calcinations at 900°C yield Y3Ba5Cu8O18 nanocrystalline powders. The TG/DTA analysis reveals that the precursor gels with 0.3⩽ c/n <1.0 decomposed in a single-step reaction combusted at temperature of around 230°C. Established from XRD and SEM characterization, the Y3Ba5Cu8O18 calcined powder prepared from c/n =0.7 precursor gels has got the orthorhombic structure with smallest particle size (∼10nm) compared to the rest of the batches. Samples with c/n =0.5 and 0.7 appeared in this work to be electrically superconducting at temperature above 100K as measured using standard four-probe technique. This emphasized on maintaining a stoichiometric or near stoichiometric reaction for the analysis. [Copyright &y& Elsevier]

Abstract: Quasi-single magnetic domain M-type barium hexaferrite powders have been synthesized via sol–gel auto-combustion route, followed by secondary heating treatment at 800°C for 4h, using barium nitrate, ferrite nitrate, ammonium nitrate, citric acid, and ammonia solution as the starting materials. The auto-combustion producing powders were γ-Fe2O3 and BaCO3 with aid of additional ammonium nitrate to increase the combustion temperature. The influences of the citric acid to metal ions (CA/M) and pH values on the gel auto-combustion, the phase compositions of the synthesized powders and their magnetic properties have been studied. The results showed that the chelation of barium and ferrite ions were important for the phase formation of barium hexaferrite: the phase compositions of the synthesized powders changed from a multi-phased mixture to a single phase of M-BaFe12O19 for the gradually complete complexing of barium and iron ions with citrate as the pH values and CA/M increased. The resulting powders demonstrated that various magnetic properties mainly depended on the variation in phase composition, sintering adhesion between grains and grown-up of crystalline sizes. With CA/M=1.5, pH 7, the synthesized powders had a particle size distribution in the range of 100–200nm and a saturation magnetization of 58.0emu/g at 12kOe. [Copyright &y& Elsevier]

• Ce 1− x La x O 2−δ (x = 0 − 0.1) solid solutions showed linear increase in ionic conductivity with La3+ • Ea is 1.49, 0.94, 0.87 and 0.70 eV for x = 0, 0.01, 0.03, 0.05 and 0.1 composition. • LDC showed highest ionic conductivity of 1.01 × 10−2 S cm−1 at 750 °C. • Electronic and ionic transference numbers are 0.20 and 0.80 at 700 °C for x = 0.1. • 0.05 LDC showed the OCV of 0.81 V and max. power density of 41 mWcm−2. [Display omitted] La-doped CeO 2 nanoparticles of composition Ce 1− x La x O 2−δ (0 ≤ x ≤ 0.1) have been studied here as prospective electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFCs). They were synthesized by auto-combustion method and the powder samples were calcined at 700 °C to get ultrafine nanocrystalline particles. They were characterized by XRD, Raman, FTIR, XPS, DRS, FESEM/EDX, particle size analyzer and ac-impedance techniques. Ionic conductivity was measured from 350 − 750 °C. The Ce 0.90 La 0.1 O 2−δ (0.1 LDC) and Ce 0.95 La 0.05 O 2−δ (0.05 LDC) showed a maximum conductivity of 8.89 × 10−3 and 8.32 × 10−3 S cm−1 at 700 °C, respectively. The σ t of 0.1 LDC = 1.01 × 10−2 S cm−1 at 750 °C. The activation energy of 0.1 LDC and 0.05 LDC was found to be 0.70 eV and 0.87 eV, respectively. These values are higher than those reported for La-doped CeO 2 in literature. The SOFC performance with 0.05 LDC as electrolyte showed open circuit voltage of 0.81 V and maximum power density of 41 mW cm−2 at 650 °C using hydrogen as fuel. [ABSTRACT FROM AUTHOR]

Magnesium chromite (MgCr 2 O 4) spinel oxide was synthesized by sol-gel auto-combustion technique. Room temperature X-ray powder diffraction pattern was refined by Fullprof which confirmed the formation of single phase cubic structure with Fd3m space group. The complex impedance spectroscopy was employed to investigate the charge transport mechanism within the temperature range of 423–573K and the impedance data were finely fitted for temperature dependent Nyquist plot to track down the equivalent circuit model [(R G C G)(R Gb Q Gb)]. The temperature and frequency dependent AC conductivity was found to follow Jonscher double power law and the slope of conductivity indicated the correlated barrier hopping (CBH) as a dominant conduction model in the material. The grain and grain boundary polarization was analyzed by electric modulus which confirmed the two phase response of the material. The dielectric relaxation exhibited dispersion in the low frequency region which owed to the interfacial effects. • The synthesis scheme is decisive to the properties and applications of spinel chromites. • Sol-gel self-combustion synthesis, structural and electrical transport study of the cubic normal spinel structured MgCr2O4 oxide material • Correlation of impedance formulism and hopping mechanism for electrical transport in the material • Dielectric relaxation and electric modulus analysis. [ABSTRACT FROM AUTHOR]