Solid-state Combustion Method Research Articles

Enhanced high-rate performance in Zn/Al dual-doped LiMn2O4 with submicron truncated structure

The Jahn-Teller effect and Mn dissolution always restrict the practical electrochemical properties of spinel LiMn2O4 cathode material. Herein, a low-temperature solid-state combustion method is employed to synthesize various truncated octahedral LiZn0.03AlxMn1.97-xO4 (x ≤ 0.08) with submicron structure. The Zn/Al dual-doping is conducive to forming {110} and {100} planes, and is also beneficial to the crystal development of LiMn2O4. It is found that as the amount of Al doping increases, the average particle size gradually decreases from 188 nm to 113 nm. In addition, the Zn/Al co-doping integrated with small particles can improve the high-rate performance. The optimal LiZn0.03Al0.03Mn1.94O4 exhibits submicron truncated octahedral morphology, high crystallinity, and good particles dispersibility. Benefiting from these structure merits, the LiZn0.03Al0.03Mn1.94O4 delivers the first discharge capacity of 113.1 mAh⋅g−1 and low capacity fade of 9.9 % after 300 cycles at 1C. It also shows the high first discharge capacity of 86.6 mAh⋅g−1 at 10C and the high capacity retention of 72.1 % after 2000 cycles. Even at ultrahigh current density of 15C and 20C, the ultralong cycling lifespans over 2000 cycles are also achieved in LiZn0.03Al0.03Mn1.94O4 cathode material. The excellent electrochemical properties are ascribed to its relatively high Li+ diffusion coefficient (1.60 × 10−11 cm2⋅s−1) and low apparent activation energy (25.45 kJ⋅mol−1) during the de-intercalation process. The Zn/Al dual-doping and submicron truncated octahedron designs of the LiMn2O4 provide a scientific reference to prepare high-performance cathode materials.

Effect of the Firing Temperatures on the Phase Evolution and Electrical Properties of 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] Ceramics Synthesized via the Solid-State Combustion Method

In this research paper, we describe 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] (BNT-BT-NBN) ceramics fabricated by the solid-state combustion technique. The phase evolution, microstructure, dielectric, ferroelectric and energy storage properties were examined. The BNT-BT-NBN powders and ceramics were calcined and sintered between 650–900 °C and 1100–1175 °C, respectively, for 2 h. All samples showed a typical perovskite structure, as revealed by X-ray diffraction. The Rietveld refinement analysis of the ceramics suggested the samples sintered between 1100 and 1150 °C had coexisting R + T phases, while the R + T+C phases were observed in the ceramics sintered at 1175 °C. The average grain size of the samples increased from 0.52 to 1.39 μm with increased sintering temperature. The density of the ceramics increased from 5.12 to 5.45 g/cm3 when the sintering temperature increased from 1100 to 1150 °C, and then decreased. Increasing the sintering temperature from 1100 to 1150 °C caused the dielectric constant at T s (ε s) and the dielectric constant at T m (ε m) to increase from 1727 to 1945 and 1564 to 1750, respectively, and then ε s and ε m declined. All BNT-BT-NBN ceramics had good dielectric temperature stability with only a±10% change when the temperature ranged from room temperature to ∼300 °C. The optimum energy-storage properties (W rec = 0.62 J/cm3 and η = 83.2%) were obtained from the BNT-BT-NBN ceramics sintered at 1150 °C for 2 h. This data indicates that BNT-BT-NBN ceramics can be useful as lead-free materials for high density energy-storage capacitors.

Phase Structure, Microstructure, and Electrical Properties of Bi0.47Na0.47Ba0.06TiO3 Ceramics with (LiNb)4+ Substituted into B-Sites

Due to the substitution of complex ions into B-sites is very interesting in recent, lead-free Bi0.47Na0.47Ba0.06Ti1− x (LiNb) x O3 (BNBT1− x LN x ) ceramics (with x = 0–0.04) were fabricated by the solid-state combustion method. The influence of (LiNb)4+ (x) on the phase structure, microstructure, and electrical properties was investigated. The X-ray diffraction (XRD) patterns exhibited a pure perovskite structure for all specimens. Coexisting rhombohedral and tetragonal phases were observed in all samples and the tetragonal phase increased with increased x, as analyzed by the Rietveld refinement method. The morphology of the BNBT1− x LN x ceramics, obtained by scanning electron microscopy (SEM), revealed almost-round grain shapes and anisotropic grain growth. The density and average grain sizes decreased from 5.84 to 5.54 g/cm3 and 1.7 to 0.9 µm, respectively, when x increased from 0 to 0.04. The grain size distribution decreased with increased (LiNb)4+ content. A reduction in the dielectric properties was observed, due to the phase ratio changing away from a morphotropic phase boundary (MPB), an inferior microstructure, and low density caused by (LiNb)4+ substitution. The (LiNb)4+ substitution induced the transition from non-ergodic relaxor to ergodic relaxor ferroelectric state.

Spectroscopic studies of metastable tetragonal ZrO2 nanocrystals

This study delves into an examination of the structural and luminescent properties of zirconium dioxide (ZrO2) synthesized via the solid-state combustion method. Nitrates are harnessed as the oxidizing agent, while glycine serves as the fuel. Two distinct compositions are explored: a stoichiometric 1:1 ratio and a fuel-enriched 1:2 ratio. The structural analysis, employing X-ray diffraction and Raman spectroscopy, predominantly manifests a tetragonal structural phase in both samples; however, a minor monoclinic phase has also been observed in the former sample. The band gap was found to be 4.50 eV and 4.28 eV for ZrO2 synthesized in stoichiometric ratio and a fuel-enriched ratio respectively. The samples also show defects assisted photoluminescence in both the samples. The thermoluminescence of samples were investigated after irradiating the samples with UV and gamma rays for different doses. The TL curves manifest a shift towards lower temperatures at higher doses. . Significantly, the sample prepared with a 1:1 nitrate-fuel ratio exhibits a more pronounced overall TL intensity. In conclusion, our findings imply that the formation of the tetragonal phase may be influenced by strain energy, rather than being solely ascribed to size effects and oxygen vacancies within the lattice.

Enhancement of the Dielectric and Energy Storage Properties of Lead-Free BNSLT Ceramics by Zr4+ Substitution into B-Sites

(Bi0.38Na0.30Sr0.28)0.98La0.02Ti1-xZrxO3 (abbreviated as BNSLT1-xZrx, with x = 0 − 0.05) lead free ceramics were fabricated using the solid-state combustion method. The phase structure, microstructure and electrical properties of the ceramics were investigated. The coexistence of the rhombohedral (R) and tetragonal (T) phases was found in all samples. Rietveld refinement confirmed that as x increased from 0 to 0.05, the rhombohedral phase increased from 41 to 60%. A nearly equal R:T phase ratio of 49:51 was obtained for x = 0.01. All ceramics displayed polygonal grain shapes with anisotropic grain growth. The average grain size of the ceramics was in the range of 0.46–0.79 µm. The optimal Zr4+ content resulted in increased grain growth and reduced pores, leading to improved electrical properties. The highest density (5.52 g/cm3), maximum dielectric constant (ε m =2156), maximum polarization (Pmax=15.36 µC/cm2) and high energy storage properties (Wtotal=0.49 J/cm3, Wrec=0.45 J/cm3, Wloss=0.05 J/cm3 and η = 90.54% at 60 kV/cm) were obtained from x = 0.01 caused by a morphotropic phase boundary (MPB) and good morphology.

Investigation of thermal properties of carbon[sbnd]containing composites obtained by solid-state combustion

Carbon-containing compositions of refractory products with additives of aluminum, silicon, graphite of fractional composition have been developed and optimized, and their technical properties, as well as the phase-mineral composition, have been determined.An experimental setup has been developed to study temperature parameters in given hypothetical layers, calculated heat fluxes and temperature stresses of carbon containing products up to 1300 °C.Temperature stresses and specific heat flows are calculated at the heating rate of the working surface from 4.3 °C/min to 55 °C/min with isothermal exposure of products at 700 °C, 950 °C and 1300 °C.This study is devoted to the technology of obtaining carbon-containing refractories by solid-state combustion method (in SHS mode) with the maximum transformation of low-melting phases into refractory ones using ferroalloy metallurgy waste, as well as to the study of thermophysical properties, composition, and influence of specific heat fluxes on temperature stresses in conditional hypothetical layers obtained carbon-containing SHS refractory products.

Influence of fuel in the bismuth oxide photocatalytic performance for the degradation of acid blue-25 under visible light

In this work, we prepared bismuth oxide (Bi2O3) nanoparticles with and without fuels (citric acid and urea) using a one-pot solid-state combustion method at 400 °C for visible light photocatalytic degradation of acid blue 25 (AB). The nanoparticle prepared with fuel greatly influences the Bi2O3 properties such as morphology, chemical, structural, and optical properties. Bi2O3 prepared with citric acid as fuel act as an effective photocatalyst for the breakdown of acid blue 25 within 60 min under visible light irradiation. The enhanced photocatalytic property of Bi2O3 is due to the narrow band gap, high crystallinity, flower-like morphology with high active sites, and light stability of the material. Furthermore, an effective photogenerated charge separation, high charge transfer, and lower band gap, improved the absorbing capacity in the visible region of Bi2O3 (1) and enhanced its photocatalytic ability. In the photocatalytic process, the superoxide radicals (O2·) anion played a significant role during the degradation of acid blue 25. The Bi2O3 (1) maintained its effectiveness after three reaction cycles without suffering any appreciable change in structural and functional stability. These findings demonstrated an easy method for treating the hazardous effluents into non-toxic small molecules, which can be potentially applied to purify the various textile effluent.

The Electrochemical Performance of LiMn1.96Mg0.04O4 Cathode Material Prepared by Solid-State Combustion Method

The Electrochemical Performance of LiMn1.96Mg0.04O4 Cathode Material Prepared by Solid-State Combustion Method

Effect of Heat Treatment Time on Electrochemical Performance of LiMg0.04Mn1.96O4cathode Materials Synthesized by a Solid-State Combustion Method

Effect of Heat Treatment Time on Electrochemical Performance of LiMg0.04Mn1.96O4cathode Materials Synthesized by a Solid-State Combustion Method

The Effect of Calcination Time on the Electrochemical Performance of Spinel LiMg0.08Mn1.92O4 Prepared by a Solid-State Combustion Method

The Effect of Calcination Time on the Electrochemical Performance of Spinel LiMg0.08Mn1.92O4 Prepared by a Solid-State Combustion Method

Radiation and Emission Phenomena in Combination

Radiation and Emission Phenomena in Combination

Synergistic effect of oxygen vacancies and built-in electric field in GdCrO3/BiVO4 composites for boosted photocatalytic reduction of nitrate in water

As a promising approach for nitrate nitrogen removal in water, photocatalysis required sufficient photogenerated charges to achieve a high photocatalytic efficiency. Herein, a novel GdCrO3/BiVO4 composite was prepared by the solid-state combustion method combined with hydrothermal treatment. The synergistic effect of oxygen vacancies introduced by chemical reduction method and built-in electric field formed in GdCrO3/BiVO4 heterostructures suppressed the charge recombination, which eventually improved the photocatalytic activity. Effects of photocatalyst composition, HCOOH dosage and oxygen vacancy concentration on photocatalytic activity were investigated. It was found that 0.30-GdBiOVs composites exhibited highest photocatalytic activity with nitrate removal ratio of 97.05% and N2 selectivity of 92.76% in 40 min. Moreover, end-products of nitrate nitrogen elimination and stability of photocatalysts were revealed. The existences of oxygen vacancies and built-in electric field were confirmed by EPR and HRTEM analyses. Ultimately, the possible mechanisms of nitrate nitrogen elimination were clarified.

CO2 Methanation: Solvent-Free Synthesis of Nickel-Containing Catalysts from Complexes with Ethylenediamine.

CO2 methanation was studied in the presence of nickel catalysts obtained by the solid-state combustion method. Complexes with a varying number of ethylenediamine molecules in the coordination sphere of nickel were chosen as the precursors of the active component of the catalysts. Their synthesis was carried out without the use of solvents, which made it possible to avoid the stages of their separation from the solution and the utilization of waste liquids. The composition and structure of the synthesized complexes were confirmed by elemental analysis, IR spectroscopy, powder XRD and XPS methods. It was determined that their thermal decomposition in the combustion wave proceeds in multiple stages with the formation of NiO and Ni(OH)2, which are reduced to Ni0. Higher ethylenediamine content in the complex leads to a higher content of metal in the solid products of combustion. However, different ratios of oxidized and reduced forms of nickel do not affect the initial activation temperature of nickel catalysts in the presence of CO2. It was noted that, after activation, the sample obtained from [Ni(C2H8N2)2](NO3)2 exhibited the highest activity in CO2 methanation. Thus, this complex is a promising precursor for CO2 methanation catalysts, and its synthesis requires only a small amount of ethylenediamine.

Solid state synthesis, characterization and biological evaluation of silver doped nanosized metal oxides

Nanomaterials have attracted a great deal of attention from the scientific community due to their unique properties and applications. The small size metal oxides have opened up the door for intensive research to utilize their properties for biomedical applications. Silver nanoparticle (AgNPs) and metal oxide nanomaterials like MgO, ZnO, NiO and its silver doped nanocomposites (Ag-MgO, Ag-ZnO, Ag-NiO) have been prepared using solid state combustion method using polyvinyl alcohol (PVA) as a fuel. The structure of as prepared oxides and its silver doped nanocomposites were characterized using X-ray diffraction (XRD) tool and morphology by Scanning Electron Micrograph (SEM) tool as well as Transmission electron micrograph tool respectively. Presence of the metals in the oxides and its Ag composite was confirmed by the EDX pattern. Bonding nature in the composite is well studied by the Fourier transform infrared (FT-IR) tool. Antibacterial activity studies of the nanocomposites are carried out against various bacteria.

Solvent-Free Synthesis of Nickel Nanoparticles as Catalysts for CO2 Hydrogenation to Methane

The solid-state combustion method was used to prepare nickel-based catalysts for CO2 hydrogenation from [Ni(C3H4N2)6](NO3)2 and [Ni(C3H4N2)6](ClO4)2. These complexes were synthesized by adding nickel nitrate and perchlorate to melted imidazole. The composition and structure of the obtained complexes was confirmed by ATR FTIR, powder XRD, and elemental analysis. The stages of thermal decomposition of the complexes and their kinetic parameters were established. It was found that incomplete gasification of more thermostable Ni(C3H4N2)6](ClO4)2 led to the formation of carbon, nitrogen, and chlorine impurities. According to powder XRD and XPS, the solid products of gasification of both complexes consist of NiO and Ni0 covered with nickel hydroxide and/or a carbonate layer. In the case of the sample prepared from [Ni(C3H4N2)6](ClO4)2, this layer was pronounced. Therefore, it limits the nickel reduction in the reaction medium of CO2 hydrogenation, even at 450 °C. The surface of the sample prepared from [Ni(C3H4N2)6](NO3)2 contains nickel oxide, which is easily reduced. So, the catalyst active phase is already formed at 250 °C in the presence of CO2 and efficiently catalyzes CO2 hydrogenation as the temperature increases. Therefore, [Ni(C3H4N2)6](NO3)2 is a promising precursor for the CO2 hydrogenation catalyst, and its solvent-free synthesis follows Green Chemistry principles.

Improved long cycle performance of LiMn2O4 cathode material by Ni-B co-doping combined with truncated octahedron morphology

The rapid capacity fading of spinel LiMn2O4 cathode materials still suffers from Jahn-Teller effect and Mn dissolution. Herein, various spinel LiMn1.90-xNi0.10BxO4 cathode materials with truncated octahedron morphology are obtained by a solid-state combustion method. Owing to the substitution of Ni-B dual-doping for Mn, the MnO6 octahedron in the LiMn2O4 generates a contraction that leads to the increased average Mn oxidation state and the suppressed Jahn-Teller effect. Simultaneously, the expansive LiO4 tetrahedron is conducive to boosting the fast Li+ diffusion. Moreover, the growth of {110} crystal planes in the LiMn1.90-xNi0.10BxO4 (x = 0.02–0.15) is also restrained by the Ni-B co-doping, hence alleviating the Mn dissolution. So the Ni-B co-doping accompanied with truncated octahedron morphology presents the preferential growth of {111} and {100} planes. Among the various counterparts of Ni-B co-doping, the optimized LiMn1.84Ni0.10B0.06O4 exhibits the optimal rate performance and cycle life. At 5 C, a capacity retention of 73.5% with an initial discharge capacity of 101.8 mAh g−1 is achieved after ultra-long 2000 cycles. Even at 10 C, the capacity retention of 62.2% is also maintained after 2000 cycles. This combination of element doping and morphology regulation will provide a feasible strategy to synthesize high-performance spinel LiMn2O4 cathode materials for lithium-ion batteries.

Facile Synthesis of ZnO-CeO2 Heterojunction by Mixture Design and Its Application in Triclosan Degradation: Effect of Urea.

In this study, simplex centroid mixture design was employed to determine the effect of urea on ZnO-CeO. The heterojunction materials were synthesized using a solid-state combustion method, and the physicochemical properties were evaluated using X-ray diffraction, nitrogen adsorption/desorption, and UV–Vis spectroscopy. Photocatalytic activity was determined by a triclosan degradation reaction under UV irradiation. According to the results, the crystal size of zinc oxide decreases in the presence of urea, whereas a reverse effect was observed for cerium oxide. A similar trend was observed for ternary samples, i.e., the higher the proportion of urea, the larger the crystallite cerium size. In brief, urea facilitated the co-existence of crystallites of CeO and ZnO. On the other hand, UV spectra indicate that urea shifts the absorption edge to a longer wavelength. Studies of the photocatalytic activity of TCS degradation show that the increase in the proportion of urea favorably influenced the percentage of mineralization.

Effect of La2O3 Doping on Phase Formation, Microstructure and Electrical Properties of (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3 Ceramics Synthesized via the Solid-State Combustion Method

In this work, the effect of La2O3 doping (x = 0–1.6 wt%) on the phase formation, microstructure and electrical properties of (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3 (KNLNTS) ceramics was investigated. These samples were fabricated by the solid-state combustion method using glycine as fuel. The KNLNTS ceramics doping with La2O3 powders were calcined and sintered at 750 °C and between 1100 and 1200 °C, respectively, for 2 h. From the X-ray diffraction (XRD) results, the ceramics had a pure perovskite phase with coexisting orthorhombic and tetragonal phases in all samples. The Rietveld refinement analysis suggested that the tetragonality increased with increasing La2O3 doping. The grain morphology of the ceramics exhibited a rather square shape. The average grain size and the density of the ceramics tended to decrease from 1.5 to 0.7 µm and 4.71 to 4.56 g/cm3, respectively, when increasing La2O3 contents from 0 to 1.6 wt%. The dielectric behavior of the ceramics degenerated with La2O3 doping. A decrease in the leakage current and saturated hysteresis loops were observed in the samples doped with La2O3 ≥ 0.8 wt%.

Effect of Fe2O3 Doping on Phase Formation, Microstructure, Dielectric and Magnetic Properties of BNT-BKT-KNN Ceramics Prepared by the Solid-State Combustion Technique

Lead-free 0.81(Bi0.5Na0.5TiO3)-0.18(Bi0.5K0.5TiO3)-0.01(K0.5Na0.5NbO3) (BNT-BKT-KNN) ceramics doped with Fe2O3 (0–0.8 wt%), were prepared via the solid-state combustion method using glycine as fuel. The effect of Fe2O3 doping on the phase formation, microstructure, dielectric and magnetic properties of the ceramics was investigated. The XRD and Raman spectra of all ceramics indicated a pure perovskite structure with coexisting rhombohedral and tetragonal phases. The microstructure showed a polygon grain shape for all compositions. The average grain size and density of the ceramics tended to increase from 0.38 to 0.77 μm and 5.56 to 5.80 g/cm3 with increasing x content. The ceramics with 0.4 wt% Fe2O3 doping showed the highest maximum dielectric constant (ε m =5424) which corresponded to the microstructure and density results. Without Fe2O3 doping, the BNT-BKT-KNN ceramic showed diamagnetic behavior, whereas all of the Fe2O3 doped ceramics exhibited paramagnetic behavior, measured at a temperature of 25°C.

Sintering Temperature Effect on the Structural Phase, Microstructure and Electrical Properties of 0.92BNKLT-0.08BST Ceramics Prepared via the Solid State Combustion Method

Binary system ceramics of 0.92Bi0.5(Na0.68K0.22Li0.10)0.5TiO3-0.08Ba0.5Sr0.5TiO3 (abbreviation as 0.92BNKLT-0.08BST) were prepared by the solid-state combustion method. Different sintering temperatures (between 1050 and 1150 °C for 2 h) were investigated for their effects on the structural phase, microstructure and electrical properties. 0.92BNKLT-0.08BST ceramics showed a pure perovskite structure with coexisting phases of rhombohedral and tetragonal, in all samples. The tetragonality and the lattice parameters increased with increasing sintering temperatures. The ceramics’ grains showed polygonal shapes with anisotropic growth. The average grain size increased from approximately 0.35 to 0.83 µm when the sintering temperature increased from 1050 to 1150 °C. The highest density of 5.83 g/cm3 and the maximum dielectric constant at Tm (εm) 5006 were obtained by the sample sintered at 1100 °C for 2 h. With higher sintering temperatures, the P-E hysteresis curves exhibited more pinched loops which indicated higher relaxor behavior. A large strain of 0.21% and a high normalized strain piezoelectric coefficient (), around 420 pm/V, were achieved at the sintering temperature of 1125 °C for 2 h.