Self-propagating Combustion Method Research Articles

Study on synthesis and properties of Na+–La3+ co-doped γ-Ce2S3 pigment by low-temperature self-propagating combustion method

Study on synthesis and properties of Na+–La3+ co-doped γ-Ce2S3 pigment by low-temperature self-propagating combustion method

Exploring the potential of Sm3+-doped Sr2B2O5 phosphors for bridging the amber gap in w-LED application

A series of orange-red emitting Sr2(1-x)B2O5:2xSm3+(x = 0.5–3.0 mol%) phosphors have been synthesized via the self-propagating low-cost solution combustion method. The purpose of this study is to address the amber gap in light-emitting diodes (LEDs). X-ray diffraction technique was employed for structural analysis, which reveals the creation of a purely monoclinic phase having space group P21/a. The optical characteristics of synthesized Sr2B2O5:Sm3+ phosphor were investigated via Photoluminescence (PL) and UV–Vis spectroscopy. The findings of the PL studies indicate that the phosphors doped with Sm3+ ions exhibit distinct emission peaks at 565 nm, 604 nm, 649 nm, and 712 nm when excited by a wavelength of 404 nm. These peaks are ascribed to electronic transitions from 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2, 11/2) energy levels. The temperature-dependent PL studies suggest that the synthesized phosphors display a remarkable thermal stability of 96.1 % and 90 % at 150 ℃ and 200 ℃, respectively. The Diffused Reflectance Spectrum was utilized to estimate the optical band gap energy. The CIE coordinates (0.6, 0.39) for the phosphors were found to be in the orange-red region exhibiting a towering color purity of 98.6 %. The aforementioned findings demonstrate the prepared phosphors will be an auspicious candidate for amber LEDs for automotive illumination.

Heteroatom-modulated NiCo2O4 apparent energy activation of PMS for tetracycline removal: Mechanism and toxicity analysis

Heteroatom doping to reconfigure the electronic structure of heterogeneous catalysts is expected to lead to the development of advanced oxidation water purification materials with superior performance and greater stability. Herein, a series of catalysts with different elemental doping was developed by a simple and environmentally friendly one-step self-propagating combustion method to remove Tetracycline (TC). After S-doping, the normalized kinetic constant of TC was significantly increased from 30.49 to 159.41 min−1M−1 within 30 min, which is even higher than most recent heterogeneous catalysts. The prepared S-doped NiCo2O4 (NCO–S) exhibits an extremely promising catalytic performance for oxidation (92.8 %) and mineralization (65.9 %) of TC in a wide pH range (3–11). The resistance to interference is excellent for inorganic ions and even in real water samples. Quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analyses demonstrated that the non-radical oxidation pathway, including electron transfer and 1O2, dominated the degradation process after S doping. It is speculated that possible intermediates and toxicological studies are discussed, finding that the overall degradation process is moving towards low toxicity to reveal prospects for large-scale applications. This work not only provides a way to remove TC, but may also inspire the design of more efficient and stable materials for water treatment and other applications.

Investigation of Structural, Dielectric and Optical Properties of Polyaniline-Magnesium Ferrite Composites.

A study on the influence of magnesium ferrite nanoparticles on the optical and dielectric attributes of Polyaniline has been conducted. Magnesium nano Ferrite powder is synthesized by the self-propagating solution combustion method. Polyaniline-Magnesium nano ferrite composites are synthesized by chemical oxidative polymerization of aniline with the addition of Magnesium nanoparticles. The samples are characterized with XRD and UV-Vis spectrometer, in the wavelength range of 200-800 nm and studied for optical properties. Dielectric properties are studied in the frequency range of 50 Hz to 5 MHz. X-ray diffraction reveals single phase formation of Magnesium ferrite, whereas Polyaniline shows an amorphous nature. In the XRD of the composites, we see the crystalline peaks of ferrite becoming more intense with the addition of ferrite and whereas the peak of Polyaniline diminishes. The crystallite size is quantified with the Debye-Scherrer formula, and it increases as the content of ferrite in the composites increases. The micro-strain decreases in the composites as the percentage of ferrite enhances in the composites. In the UV-Vis absorption spectra of composites, the peaks of Polyaniline shift to higher wavelength and there is also an absorption band in the spectra of composites corresponding to that of Magnesium ferrite particles. Both direct and indirect band gaps are calculated with the Tauc plot, and both the optical band gap decrease as the percentage of ferrite increases in the composite. The dielectric loss and dielectric constant both decrease with frequency in all the samples, and the dielectric response are in good agreement with Maxwell-Wagner model. Ferrite-polymer composites with both conducting and magnetic properties are considered useful for electromagnetic shielding and microwave absorption.

Synthesis, Characterization and Investigation of Optical and Electrical Properties of Polyaniline/Nickel Ferrite Composites.

Nickel ferrite nanoparticles are prepared by using a low-temperature self-propagating solution combustion method using urea as fuel. The prepared nickel ferrite nanoparticles were doped with polyaniline in the three different weight ratios of 10%, 30% and 50% by using an in situ polymerization method and by adding ammonium persulfate as an oxidizing agent. The obtained samples were characterized by using XRD, FTIR, SEM and a UV-visible spectrophotometer. XRD examined crystalline peaks of ferrites and amorphous peak of polyaniline and confirmed the formation of the composites. FTIR examined the chemical nature of samples and showed peaks due to polyaniline and the characteristic peaks that were less than 1000 cm-1 wavenumber were due to metal-oxygen bond vibrations of ferrites. AC conductivity increased with frequency in all samples and the highest AC conductivity was seen in polyaniline/nickel ferrite 50%. DC conductivity increased in all samples with the temperature showing the semiconducting nature of the samples. Activation energy was evaluated by using Arrhenius plots and there was a decrease in activation energy with the addition of ferrite content. The UV-visible absorption peaks of polyaniline showed shifting in the composites. The optical direct and indirect band gaps were evaluated by plotting Tauc plots and the values of the optical band gap decreased with addition of ferrite in polyaniline and the Urbach energy increased in the samples with 10%, 30% and 50% polyaniline/nickel ferrite composites. The optical properties of these composites with a low band gap can find applications in devices such as solar cells.

Self-propagating combustion synthesized magnetic cobalt carbohydrate-based adsorbents for tetracycline elimination

Herein, a series of adsorbent magnetic cobalt carbohydrate-based (carbon source: glucose, maltose, and starch) carbon adsorbents (Co-Cs) can be rapidly prepared for the removal of tetracycline (TC) from water using a self-propagating combustion method. The results of batch adsorption experiments show that the composites exhibit excellent adsorption performance (maximum adsorption capacity of 430.54 mg/g) towards TC in a wide pH range of 2–10. As the concentration of humic acid (2–10 mg/L) increased, its adsorption capacity enhanced from 176.51 to 281.63 mg/g by forming bridge bonds. Pseudo-second-order kinetic and Freundlich models are more suitable for describing adsorption data. In addition, the hydrogen bond, complexation, and conjugation effect were the major adsorption mechanisms. The adsorption experiments of high concentration TC water samples were tested with hospital wastewater (adsorption capacity up to 236.31 mg/g), which provided some guidance for further practical application. The proposed synthetic strategy provides an efficient, excellent versatility and energy saving method for the preparation of high-performance magnetic adsorbents.

Crystallite size reduction of Cr doped Al2O3 materials via optimized high-energy ball milling method

α-Al2O3 based compounds have large crystals and it is very difficult to reduce the crystallite size because they are very stable and hard. One way of reducing the crystallite size of the materials is by using high-energy ball milling method. Pure and single-phase micron-sized α-Al2−xCrxO3 (x = 0.1, 0.2, 0.3) materials were successfully obtained via self-propagating combustion method. These materials were then subjected to a simple milling process from their microcrystalline powders. Comparisons between the micron-sized and milled samples in terms of their phase, structure, morphology and crystallite size were discussed. The XRD results reveal that all the milled samples were pure with no impurity or other phases present. Structural parameters are extracted via the Rietveld method, revealing that the cell constant, a, of the milled samples is higher than that of the micron-sized materials by 0.09 % to 0.11 %, resulting in a 0.28 % to 0.39 % increase in cell volume. FESEM results show a gradual decrease in crystallite size with increased milling time. Notably, the method successfully reduces the crystallite size without changing the phase of the materials and preserving the stoichiometry of the Al2−xCrxO3 materials which may offer improved properties in various applications.

Formation of porous Fe3O4/Ag composite by self-propagating combustion for lightweight and efficient microwave absorption

Due to the growing demands for radar stealth and electromagnetic pollution prevention, EM-waves absorbing materials with lightweight, broad bandwidth, thin thickness and strong strength are in high need nowadays. However, the achievement of both lightweight and efficient absorption still remains a challenge. In this work, the porous Fe3O4/Ag composites are successfully synthesized by a self-propagating combustion method, which has the advantages of simplicity, green and high yield. The magneto-electric synergy components and porous microstructure not only effectively reduces the density of the composites, but also significantly reinforces the absorption of EM waves. The sample with Fe3O4/Ag molar ratio of 4:1 attains the maximum reflection loss of −45.01 dB at the matching thickness of 1.85 mm and it can realize dramatical reduction of RCS signal by coating on the perfect electric conductor. The findings shed light on the promising application of the porous Fe3O4/Ag composites in the fields of environmental protection and military stealth.

Honeycomb-like structured ZnFe2O4@C derived from ZnFe2O4@ZIF-8 for electromagnetic wave absorption

In this paper, ZnFe2O4@Zeolitic imidazolate framework-8 (ZIF-8) composites were prepared by Sol-Gel self-propagating combustion method and in situ growth method. Honeycomb-like structured ZnFe2O4@C composites were obtained using ZnFe2O4@ZIF-8 as the precursor in Ar atmosphere carbonization at 800℃. The honeycomb-like structure is conducive to enhance the polarization and reflection on the surface of powder particles, which ameliorate the EMW absorption properties of the materials significantly. Wherein, the carbon content can be controlled by ZIF-8 coating. The composite with 5% ZIF-8 (wt%) shows excellent reflection loss value of −36.5 dB at 9.4 GHz with a matching thickness of 2.0 mm, and the corresponding effective absorption bandwidth is 3.5 GHz (7.6–11.1 GHz). The composite with 10% ZIF-8 (wt%) obtain a minimum reflection loss value of −37.8 dB at 10.0 GHz when the thickness is 2.0 mm, and the effective absorption bandwidth is 3.5 GHz (7.9–11.3 GHz).

Electrospun of MgMn2O4 based cathode materials for rechargeable magnesium ion cells

In this work, a combination of self-propagating combustion method with an electrospinning technique has been performed. The process been carried out by using solutions of polyacrylonitrile (PAN) diluted in N,N dimethylformamide (DMF) and MgMn2O4 with a ratio of 1:1, a uniformly nanoparticles fiber was obtained. The process was conducted at parameters of 18 kV applied voltage, collector distance of 15 cm, and a flow rate of 1 ml/h. Field Emission Scanning Electron Microscopy (FESEM) studies indicate that MgMn2O4 samples shown a small particle size of 49.6 nm. The electrospun of MgMn2O4 is a promising approach to obtain novel cathode materials product for magnesium ion cells.

Broadband electromagnetic wave absorption of Ni0.5Zn0.5Nd0.04Fe1.96O4 ferrites modified by nano-silver particles

Ferrite materials have the potential to become excellent absorbing materials due to their high magnetic loss and good impedance matching. However, the disadvantages of high density and lack of dielectric loss capability limit its application. Herein, we used the citric acid sol-gel method and the self-propagating combustion method to prepare neodymium-doped nickel-zinc ferrite (NZNF), then the target effect of Sn2+ and an improved electroless silver plating process was used to plate a layer composed of silver nanoparticles (Ag NPs) with strong dielectric loss on the NZNF, and a magnetic/dielectric composite material (NZNF@Ag) with a heterogeneous structure was prepared. The number and particle size of Ag NPs on the surface of NZNF can be precisely controlled, thereby greatly enhancing the dielectric loss capability with little impact on the magnetic loss. The huge difference in conductivity between conductors and semiconductors promotes the occurrence of polarization at the heterogeneous interface and significantly enhances the electromagnetic wave absorption ability of the composite material. In the 2–18 GHz frequency band, the best sample can obtain an effective bandwidth of 6.82 GHz when the matching thickness is 2.1 mm. Combining conductors with semiconductor materials to obtain significantly enhanced interfacial polarization provides a new idea for improving the performance of wave absorbing materials.

Preparation and study of borate glass-ceramics coated γ-Ce2S3 red pigment

In this study, the core–shell wrapping structure red pigment with γ-Ce2S3 colorant as core and borate glass-ceramics as shell was prepared by low temperature self-propagating combustion method with solid sulfur as sulfur source. The effects of H3BO3 addition amount on the chromaticity and temperature stability of the coated pigment were studied. It was found that when the addition amount of nB/Ce was equal to1.40, the coated pigment with the optimal stability and chromaticity value can be obtained, and its redness value (a*) was 42.01. This coated pigment still maintained a certain redness (a*=30.86) after calcined at 680 °C for 10 min in air. This indicates that the temperature stability of borate glass-ceramics coated γ-Ce2S3 red pigment with core–shell structure can be improved from 350 °C to 680 °C.

Synthesis and Microstructure Investigation of Ni40Ti50Cu10 Intermetallic Shape Memory Alloys by Self-Propagating Combustion Method

Synthesis and Microstructure Investigation of Ni40Ti50Cu10 Intermetallic Shape Memory Alloys by Self-Propagating Combustion Method

Influence of Ti and Fe doping on the structural and electrochemical performance of LiCo0.6Ni0.4O2 cathode materials for Li-ion batteries

The combination of lithium cobalt oxide (LCO) and lithium nickel oxide (LNO) property for Li-ion batteries (LIB) brings a very promising cathode material, LiCo1−xNixO2 with a high specific reversible capacity and good cycling behaviour. Nonetheless, high toxic Co content and an instability of Li+/Ni2+ interaction in LiCo1−xNixO2 crystal structure paved the way for some modification for the development of this potential material. In this research, the self-propagating combustion method is used to reduce 40% Co content of LCO by replacing it with 40% Ni content resulting in cathode material with the stoichiometry of LiCo0.6Ni0.4O2 (LCN). To improve the stability of the LiCo0.6Ni0.4O2 structure, 5% of Ti and Fe was substituted at the Co site of the LCN material. The effect of these different cation substitutions (Ti4+ and Fe3+) on the structural and electrochemical performance of layered LiCo0.6Ni0.4O2 cathode materials was investigated. Rietveld refinement revealed that Fe doped material has the longest atomic distance Li–O in the structure that allow better Li+ diffusion during intercalation/deintercalation to give an excellent electrochemical performance (138 mAhg−1). After 50th cycle, it is found that the discharge cycling for Ti and Fe substituted materials were improved by more than 5% compared to pristine material. Both Ti and Fe doped materials were also having less than 13% of capacity fading indicates that the substitution of some Co with Ti and Fe are stable and can retain their electrochemical properties.

Facile synthesis of Zn0.5Ni0.5Fe2O4/carbon nanocomposite for hyperthermia and drug delivery applications

Zn0.5Ni0.5Fe2O4 nanopowders as heating agents could be used for hyperthermia due to their magnetic characteristics. However, due to the lack of suitable surface properties, magnetic ferrites do not have proper drug absorption capacity and sometimes show cytotoxicity. These concerns limit their application in medical use. A simple one-step method to synthesize the Zn0.5Ni0.5Fe2O4/carbon nanocomposite is an effective strategy to solve these issues. Metal salts and citric acids were dissolved in water and heated till combustion was taken place. In this procedure, the synthesis of magnetic material and carbonization occurred simultaneously. The results showed that Zn0.5Ni0.5Fe2O4 nanoparticles were uniformly engulfed into carbon produced by a self-propagating combustion method. Magnetic properties of Zn0.5Ni0.5Fe2O4/C nanocomposite showed the ferrimagnetic characteristics with the saturation magnetization of about 54 emu/g. The specific loss power (SLP) values of the samples heat-treated at 100 and 400 °C were 14 and 42 W/g, respectively. The produced samples were loaded with cephalexin. The cephalexin-loaded Zn0.5Ni0.5Fe2O4/C nanocomposite demonstrated controlled drug release, efficient antibacterial characteristics against Staphylococcus aureus, and Escherichia coli, and significant hyperthermia ability. Therefore, the synthesized nanocomposites might open up a way for efficient hyperthermia and drug release applications and have a prospective use in medical science.

Facile synthesis of high colour rendering BiVO4 yellow pigment via self-propagating combustion method

High colour rendering bismuth vanadate (BiVO4) pigments were successfully synthesized by self-propagating combustion method at low temperature (200?C). Interestingly, the addition of citric acid as a fuel was beneficial to the formation of well-dispersed olive-like BiVO4 particles with the size around 730 nm. Furthermore, the as-prepared pigments also exhibited high purity m-BiVO4 phase and brilliant yellow hue (b* = 78.12), which is better than that of previously reported in literature and commercially available BiVO4 yellow pigments. Importantly, the pigments were applied in various substrates (PMMA, glass and ceramics), and showed excellent colour rendering, dispersion properties, thermal and chemical stability, indicating its potential application in the high-grade plastic, glass and ceramic-ware decoration.

Investigating the effect of Pr doping BiFeO3 on the microwave absorption and magnetic properties

Bi1-xPrxFeO3 material with perovskite structure was prepared using organic tartaric acid-assisted sol–gel self-propagating combustion method to obtain high-efficiency microwave absorption materials. The influence of the introduction of Pr on dielectric properties and permeability was further studied. After 15% Pr introduced, the lowest reflection absorption loss reaches –32.34 dB, but the absorption bandwidth is only 2.25 GHz. When Pr is 5%, the lowest reflection absorption loss value of −27.31 dB is obtained, and the effective bandwidth which below −10 dB is 3.41 GHz. The structural changes in the process of Pr replacing Bi were analyzed to explore the properties of BPFO perovskite. The influence of strong interaction force, residual magnetization, and natural resonance of ceramic nanoparticles on microwave absorption performance was explored. This work supplies a reliable candidate material for making up electromagnetic attenuation ceramic materials with excellent properties.

An exceptional dielectric-magnetic-type ErFeO3/polyaniline composites for microwave-absorbing application

The organic-inorganic ErFeO3/polyaniline (ErFeO3/PA) composites were synthesized by combining sol-gel self-propagating combustion method and in-situ oxidative polymerization method. The microstructure, FTIR spectra, surface area and pore volume, magnetic properties and electromagnetic parameters of the synthesized samples were studied in detail. The reflection loss of obtained products in the frequency range of 1–18 GHz was calculated. In addition, the effects of different concentrations of ErFeO3/PA on microwave-absorption properties were studied. The sample of 30 wt% ErFeO3/PA in paraffin matrices had good absorption properties. When the given thickness was 2.0 mm, the reflection loss (RL) lower than −10 dB was in the 12.1–16.3 GHz range, covering almost two-thirds of the Ku band (12–18 GHz), and the maximum RL reached − 39.0 dB. The combination of ErFeO3 and PA generated plenty of heterogeneous interfaces and induced the multipolarization process in heterogeneous interfaces, resulting to the excellent microwave-absorbing properties.

Effect of microcosmic regulation of unit cells bonding on microwave absorption properties of perovskite structure GdFeO3

GdFe1-xNixO3 material with perovskite structure was prepared using organic monohydrated citric acid-assisted sol–gel self-propagating combustion method to obtain high-efficiency microwave absorption material with thin thickness and wide effective absorption band. The influence of the introduction of Ni on dielectric properties and permeability was further studied. Experimental results show that with the introduction of 10% Ni, the lowest reflection absorption loss value of -49.5 dB is obtained, but the absorption bandwidth is only 0.89 GHz. When Ni is 15%, the lowest reflection absorption loss value of -38.8 dB is obtained, and the effective bandwidth (< -10 dB) is 5.32 GHz. The structure of GdFe1-xNixO3 perovskite was analyzed to explore structural changes in the process of Ni replacing Fe. The influence of strong interaction force, residual magnetization, and natural resonance of ceramic nanoparticles on microwave absorption performance was explored. This work provides a reliable candidate material for the synthesis of electromagnetic attenuation ceramic materials with excellent properties.

Enhancing the structural stability and capacity retention of Ni-rich LiNi0.7Co0.3O2 cathode materials via Ti doping for rechargeable Li-ion batteries: Experimental and computational approaches

The Ni-rich cathodes are considered as the next generation candidate cathode material of lithium-ion batteries due to their high-energy–density and environmentally friendly. In this study, the Ni-rich, LiNi0.7Co0.3O2 cathodes material was doped by titanium (Ti) via a self-propagating combustion method. The role of Ti species and its effects on the structural and electrochemical performance of the cathode materials were investigated through experimental and first principles studies. From the XRD results, all materials possessed a single phase with a hexagonal layered structure of the R-3m space group. The Rietveld refinement revealed that the lattice of the Ti-doped LiNi0.7Co0.3O2 sample was found to be expanded in the c-axis and has a lower cation mixing as compared to the pristine samples, which can ease the movement of Li-ions during the delithiation/lithiation process. After 70th cycle, the discharge capacity of the Ti-doped LiNi0.7Co0.3O2 sample possess an excellent capacity retention of 91.9% with a specific discharge capacity of 132.3 mAhg−1 as compared to the pristine sample with only has 86.2 mAhg−1. This can be explained by first-principles study where it was found that the Li-O distances for LNCT become expand after the delithiation process which ease the Li-ions diffusion during cycling. As a whole, the addition of Ti species into the Ni-rich layered cathode materials was found to stabilise the crystal structure of LiNi0.7Co0.3O2 and subsequently improved the lithium-ion kinetics of the layered cathode materials. Apart from lithium nickel manganese cobalt oxide (NMC) and lithium nickel cobalt aluminium oxide (NCA), this study demonstrated that LiNi0.6Co0.3Ti0.1O2 can also serve as potential cathode material for rechargeable Li-ion batteries.