Simultaneous Thermal Analysis Research Articles

Preparation of microencapsulated physicochemical composite retardant and study of the flame retardant mechanism

In order to solve the shortcomings of traditional inhibitors, which are easy to be interfered by the outside world during the inhibition process and the active ingredients are easy to be oxidized and invalidated, microencapsulated inhibitors were developed. In this study, we prepared microencapsulated inhibitors of varying wall-to-core ratios using a composite phase of polyethylene glycol 20,000 (PEG-20000) and octenyl amyl succinate (OSAS) as the wall material and a lauryl glucoside (APG-12) and butyl hydroxyanisole (BHA) phase as the core material. After thoroughly mixing the microcapsule inhibitor with coal samples, simultaneous thermal analyzer (TG/DSC) and a temperature-programmed system were used to evaluate the resisting qualities of the produced microencapsulated inhibitors. The results of the temperature programmed experiment showed that the overall CO release from the blocked coal samples was less than that of the original coal. According to thermogravimetric results, the most effective inhibition occurred when the wall/core ratio of the microcapsule inhibitor was 4:1. This also resulted in a reduction of the maximum coal weight loss rate from 1.34 to 0.96 %/min and an increase in the maximum coal weight loss temperature from 477.4 to 507.6 °C. The microencapsulated inhibitor melts in the wall at 57.4 °C, enabling temperature-sensitive intelligent control of core release. Following heating the raw and inhibited coal samples to 100 and 200 °C, respectively, Fourier infrared spectroscopy was conducted. At these temperatures, the amounts of ether bonds increased by 20.4 and 22.6 %, and the number of free hydroxyl groups decreased by 12.8 and 2.7 %, respectively, in the inhibited coal samples. Finally, molecular dynamics theory was applied to investigate the inhibitory mechanism. The prepared microcapsule retardant effectively inhibited the spontaneous combustion reaction of coal, suggesting this microcapsule inhibitor could be manufactured as a novel inhibitor for coal spontaneous combustion.

A high-speed method to obtain Ni-Zn ferrite nanoparticles by microwave hydrotalcite decomposition for magnetic applications

Nanoparticles of Zn0.375Ni0.625Fe2O4 ferrite were successfully synthesized using an innovative, rapid, and efficient synthesis method based on microwave-assisted hydrotalcite decomposition, enabling nanoparticle crystallization in less than 15 minutes. A single composition was studied to better assess the impact of the synthesis method on structural, morphological, and magnetic properties. This new synthesis route was compared with the traditional ceramic method. The prepared hydrotalcite was analyzed by high-resolution transmission electron microscopy (HRTEM), identifying hydrotalcite diffraction planes consistent with selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns. The decomposition phases of the hydrotalcite were identified by simultaneous thermogravimetric and differential thermal analysis (DTA/TG). After hydrotalcite decomposition, the ferrite obtained was analyzed by XRD, confirming a single-phase cubic structure. Scanning electron microscopy (SEM) micrographs revealed nanoparticles less than 100 nm in size with the new method and larger than 2 µm with the traditional route. At a temperature of 5 K, the M-H graph obtained with a superconducting quantum interference device (SQUID) indicated that the spinel-type ferrite exhibited a smooth ferrimagnetic behavior, which was also corroborated by electron paramagnetic resonance (EPR). Magnetic saturation values of 105.73 emu/g were obtained in the synthesis microwave-assisted hydrotalcite decomposition and 51.49 emu/g in the traditional synthesis, representing an increase of over 100 %. The two synthesis methods were also compared using density functional theory (DFT) calculations, confirming the influence of morphology on magnetic properties, obtained thanks to different synthesis methods. These results indicate that the synthesized Ni-Zn spinel ferrite nanoparticles can be used in high-frequency applications, such as ceramic induction plates.

Acidic pathway in formation of SiO2–AlO2–PO2 geopolymeric ceramic: Investigation of structural evolution and electrical behaviour

The investigation into the acidic pathway in geopolymer formation has been overlooked compared to the alkaline pathway. This study seeks to fill the gap by exploring the development mechanism and electrical properties of this type of geopolymer. The microstructural properties of geopolymer ceramics were assessed through the deconvolution of attenuated total reflectance-Fourier-transform infrared spectra (ATR-FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), simultaneous thermogravimetric analysis and differential thermal analysis (TGA/DTA). Furthermore, the electrical properties of the prepared ceramics were monitored using solid-state impedance spectroscopy (ss-IS). Maintaining an Al to P molar ratio of 1:1, various post-treatment temperatures (60 °C, 105 °C, 300 °C, 1200 °C) were employed to observe their effects on the (micro)structural properties of the samples under investigation. This ratio ensures the formation of an amorphous structure of SiO2·Al2O3·P2O5·nH2O. Additionally, the emergence of new crystalline aluminium and phosphate phases was observed.

Pyrolysis kinetics of waste ryegrass under nitrogen and air atmosphere

To investigate the pyrolysis reaction of ryegrass, we conducted a simultaneous thermal analysis using thermogravimetric(TG) analyzers. This involved obtaining data through Thermogravimetry (TG), Derivative Thermogravimetry (DTG), and Differential thermal analysis (DTA) techniques. The experiments were conducted under dynamic nitrogen and air atmospheres at different heating rates. The kinetic parameters of ryegrass pyrolysis were determined using the Kissinger method, the Flynn-Wall-Ozawa (FWO) peak conversion rate approximate equivalence method, the Flynn-Wall-Ozawa (FWO) equal conversion rate method, and the Škvára-Šesták (S–S) method. It provides a theoretical basis for the reuse of ryegrass resources. The findings indicated that the pyrolysis temperature of ryegrass increased with the accelerated rate of temperature increase in both atmospheres. The average weight loss rate of pyrolysis of ryegrass in the air atmosphere (92.27 %) is higher than that compared to that in a nitrogen atmosphere (86.11 %). Additionally, the temperature required for complete decomposition is lower in the former case. The FWO peak conversion rate approximation equivalence approach and the FWO equal conversion rate method do not apply to the solution of the pyrolysis activation energy of ryegrass. The pyrolysis activation energy for the two decomposition stages, as calculated by the Kissinger method, is 165.73 and 185.86 kJ/mol−1 in the air atmosphere, and 219.99 and 277.02 kJ/mol−1 in a nitrogen atmosphere, respectively. The activation energy and mechanism function of ryegrass pyrolysis calculated by using the S–S method are as follows: [−ln(1−α)]2, 119.79, 104.31, 95.75, and 91.93 kJ/mol−1 in air atmosphere, (1−α)−1, 176.64, 67.89, 61.15, and 54.25 kJ/mol−1 in nitrogen atmosphere, respectively. The activation energy of ryegrass pyrolysis, as determined by both the Kissinger method and S–S method, was found to be higher under an air atmosphere compared to a nitrogen atmosphere.

Feasibility of adding calcium hydroxide to FETNS–OPC: working performance, mechanical properties and reaction mechanism

To solve the problem of low early-phase reactivity of ferrous extraction tailings of nickel slag (FETNS), the effects of calcium hydroxide (Ca(OH)2) as an alkali activator on the working performance, mechanical properties and hydration products of FETNS–ordinary Portland cement (OPC) composite cementitious systems were studied. The addition of calcium hydroxide was found to shorten the initial setting time by about 40% and the final setting time by about 20%. The compressive strength at 3, 7, 28 and 60 days was increased by 51.95%, 45.27%, 8.53% and 8.9%, respectively, with the addition of calcium hydroxide. Microstructural assessment (by scanning electron microscopy, X-ray diffraction, simultaneous thermal analysis, nitrogen adsorption test and low-field nuclear magnetic resonance analysis) showed that the incorporation of calcium hydroxide increased the reaction degree of the FETNS–OPC system, and more calcium silicate hydrate gel and ettringite were generated to fill internal pores, thus improving the compactness of the matrix. In summary, the incorporation of calcium hydroxide stimulated the early-phase reactivity of the composite system, promoted the formation of reaction products and optimised the internal pore structure.

Enhancing sustainable energy production in the Canary Islands: Valorization of local biomass resources through thermochemical processes

Diverse biomass sources from the Canary Islands (vineyard, tomato plant residues, Canary pine needles and Pennisetum setaceum) were assessed due to their local abundance, availability, and low supply cost. Based on their physico-chemical properties, various thermochemical processes were conducted to assess their thermal degradation behaviour, using simultaneous thermal analysis, and their potential for energy production. The results indicate that while tomato plant biomass is unsuitable for thermochemical processes because of its elevated ash content and limited volatile matter, the other biomass sources show promising potential for pyrolysis and gasification, characterized by high fixed carbon content and reactivity. The yearly production of residual biomass in the Canary Islands was quantified at 87,253 tonnes. This biomass could generate an estimated 88.5 GWh of electricity annually. Considering that electricity consumption in the Canary Islands reached 8750 GWh in 2023, biomass-derived electricity could contribute approximately 1.0 % to the archipelago's energy needs. These findings highlight the significant role of local biomass resources in advancing renewable energy goals and reduce dependence on non-renewable sources, promoting a greener energy landscape for the Canary Islands.

THE MECHANICALLY ACTIVATED COMPOSITES BASED ON TUNGSTEN DISULFIDE: SYNTHESIS AND PROPERTIES

In this work, the physicochemical properties of mechano-activated composites (hereinafter referred to as the mechanocomposites) obtained by mechanical activation of commercial tungsten disulfide powder in a planetary mill were studied. Mechanical activation was carried out for 2, 4 and 8 h, but this work presents the results for the last two experiments. The acceleration of the grinding media was controlled through frequency adjustment; a frequency value of 15.5 Hz, according to calculations, corresponds to an acceleration of the grinding media of 50 m/s2 or 5G. The material of the balls from which the grinding balls are made is stainless steel. Due to the relatively low acceleration values, the problem of contamination of the sample with stainless steel components does not occur as a result of surface erosion that occurs when the balls collide with each other and with the walls of the grinding bowl. Mechanical activation was carried out in an inert argon environment, since these were preliminary studies and therefore there was a need to minimize the environmental parameters taken into account. However, the oxidation process will occur during the process of discharging the sample from the grinding bowl of the planetary mill. The resulting mechanocomposites are precursors for the synthesis of monocomponent catalysts for the processing of heavy oil residue. For this purpose, it is necessary to obtain mechanocomposites containing tungsten trioxide and tungsten disulfide. The results of an experimental study of the influence, mainly, of the duration of mechanical activation on the production of tungsten mechanocomposites are presented. The resulting compounds were characterized by X-ray phase analysis (XRD), IR spectroscopy, scanning electron microscopy (SEM), thermogravimetry (TGA) and simultaneous thermal analysis (STA). For citation: Akimov Al.S., Zhirov N.A., Sudarev E.A., Akimov A.S. The mechanically activated composites based on tungsten disulfide: synthesis and properties. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 36-43. DOI: 10.6060/ivkkt.20246708.2t.

Fe/LiNO3/TiN co–modified MgO for enhanced thermochemical energy storage performance in MgO/Mg(OH)2 cycles

MgO/Mg(OH)2 thermochemical energy storage can convert solar energy and industrial waste heat into forms that are easier to store and transport by cyclic hydration/dehydration reactions. To achieve excellent energy storage performance, cyclic stability and optical absorption capability of MgO/Mg(OH)2, Fe/LiNO3/TiN co–modified MgO were synthesized for energy storage cycles by wet-mixing method. The energy storage performance, cyclic stability and dehydration kinetics of Fe/LiNO3/TiN co–modified MgO were studied in dual fixed–bed system and simultaneous thermal analyzer. The experimental results show that the Fe and LiNO3 in the composite not only increase the hydration conversion of MgO by 6.3 times at 30 min, but also reduce the dehydration temperature and dehydration activation energy of Mg(OH)2 by 99.4 °C and 64 %, respectively. TiN overcomes aggregation of MgO and sustains the excellent porous structure, which results in only a 9 % decrease in energy storage performance of Fe/LiNO3/TiN co–modified MgO after 15 energy storage cycles. Subsequently, TiN significantly strengthens the optical absorption performance of Mg(OH)2 and photothermal temperature under xenon-lamp simulated sunlight radiation. Furthermore, density functional theory calculation reveals that Fe and Li enhance the adsorption of H2O on MgO model and reduce energy barrier for hydration reactions by 62.76 %, while TiN effectively inhibits MgO clusters migration within the material and enhances the optical absorption coefficient. Hence, Fe/LiNO3/TiN co–modified MgO shows significant research value in MgO/Mg(OH)2 energy storage process.

3D Confinement Stabilizes the Metastable Amorphous State of Antimony Nanoparticles - A New Material for Miniaturized Phase Change Memories?

The wet-chemical synthesis of 3D confined antimony nanoparticles (Sb-NP) at low and high temperatures is described. Using reaction conditions that are mild in temperature and strong in reducing power allows the synthesis of amorphous Sb-NP stabilized with organic ligands. Exchanging the organic ligand 1-octanethiol by iodide enabled to investigate the unusual strong stability of this metastable material through simultaneous thermal analysis combining differential scanning calorimetry and thermogravimetric analysis. Additionally, in situ high temperature powder x-ray diffraction (p-XRD) shows a significant increase in stabilization of the amorphous phase in comparison to thin layered, 1D confined Sb or bulk material. Further, it is shown with scattering-type scanning near-field optical microscopy (s-SNOM) experiments that the optical response of the different phases in Sb-NP make the distinctness of each phase possible. It is proposed that the Sb-NP introduced here can serve as a 3D-confined optically addressable nanomaterial of miniaturized phase change memory devices.

Fabrication and characterization of PMMA denture base nanocomposite reinforced with hydroxyapatite and multi-walled carbon nanotubes

Polymethyl Methacrylate (PMMA) is still one of the most popular denture base materials in dentistry due to its superior mechanical properties. However, its long-term use can result in defects such as low flexural strength and brittleness, which can be addressed by strengthening its mechanical properties. In this study, the effect of adding non-modified and modified hydroxyapatite nanoparticles (HaP NPs) and multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of PMMA denture base materials was investigated. First, the modified HaP (MHaP) NPs and modified MWCNTs (MMWCNTs) were prepared by a vinyltriethoxysilane (VTES) agent. Then, two-component PMMA-HaP/MHaP and PMMA-MWCNT/MMWCNT, and three-component PMMA-HaP/MHaP-MWCNT/MMWCNT composite samples were fabricated from commercial dental heat-curing acrylic resin (Acrosun) with different amounts of HaP/MHaP (3, 5, and 10 wt%) and MWCNT/MMWCNT (0.25, 0.5, and 1 wt%). The samples were investigated by Simultaneous Thermal Analysis (STA), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray Spectroscopy (EDS), Dynamic Mechanical Analysis (DMA), and Three-point flexural test. It was observed that surface modification of NPs improved the interaction of NPs and polymer chains in the matrix and resulted in better mechanical properties of nanocomposites. In the sample containing 3 wt% MHaP and 0.25 wt% MMWCNT, the flexural strength and flexural modulus were increased by 45 % and 42 % compared to the control sample, respectively, and the glass transition temperature (Tg) based on the DMA test was 152.7 °C, which was higher than in the other samples. The results of MTT assay studies indicated that adding MHaP and MMWCNT enhanced cell viability. In the PMMA- 3 wt% MHaP- 0.25 wt% MMWCNT composite, the cell viability was increased to 153.75 ± 9.7 % and confirmed its biocompatibility properties.

Regulation of crystal and microstructures of RETaO4 (RE = Nd, Sm, Gd, Ho, Er) powders synthesized via co-precipitation

Ferroelastic rare earth tantalates (RETaO4) are widely researched as the next-generation thermal barrier coatings (TBCs), and RETaO4 powders are hugely significant for synthesizing their coatings. The current research used chemical co-precipitation within an automated experimental device to synthesize RETaO4 (RE = Nd, Sm, Gd, Ho, Er) powders. The device automatically monitored and controlled the solutions’ pH, improving the chemical co-precipitation efficiency. The crystal structure and microstructure of the RETaO4 powders can be controlled by changing the annealing temperature, and the materials undergo an m'-m phase transition. The m'-RETaO4 powders exhibit nano-size grains, while m-RETaO4 powders evince micron-size grains, altered by the annealing temperatures. A simultaneous thermal analysis estimates the reversive ferroelastic tetragonal-monoclinic phase transition temperatures. Overall, this research focuses on the synthesis, crystal structures, microstructures, and phase transition of the fabricated RETaO4 powders.

NiAl-LDH/COF nanocomposite for catalyzing Knoevenagel condensation

Herein, a NiAl-LDH/COF composite was fabricated by directly synthesizing an imine-based COF on the NiAl-LDH surface and its identification was followed by fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, Energy dispersive X-ray spectrometry, Brunauer-Emmett-Teller, and simultaneous thermal analysis. This composite was utilized as a catalyst with a high surface area for the Knoevenagel condensation. Under low loading amount (10 mg), extremely short reaction times (5–25 min) and 25 °C, NiAl-LDH/COF composite promotes the condensation of malononitrile with various aldehydes to produce benzylidenemalononitrile derivatives with high yields (82–96 %) and good recyclability. The NiAl-LDH/COF was reused four times without a noteworthy loss in catalytic performance.

NOVEL INSIGHTS INTO PHASE FORMATION AND ELECTRICAL RESISTIVITY OF FeSe ALLOY PREPARED BY POWDER METALLURGY METHOD

This study prepared the FeSe alloy using a powder metallurgy route. The Fe and Se powders were weighed at an atomic ratio of Fe:Se = 1.025:1 and milled for 5 hours. A simultaneous thermal analysis (STA) was performed to observe the behavior of the milled powder during thermal changes. After packing the milled powder in a stainless-steel tube, it was compacted. Investigation was performed to observe how the tetragonal FeSe phase forms at sintering temperatures of 718 K, 818 K, and 918 K. At a sintering temperature of 718 K, the tetragonal FeSe phase was formed, as determined by our quantitative analysis of XRD. The highest tetragonal FeSe phase fraction of 68.46 wt.% was obtained at a temperature of 918 K. The lattice constants of the tetragonal FeSe for the best sample were a = 0.3773 nm and c = 0.5520 nm. The resistivity test demonstrated that all samples have a conductor phenomenon exceeding 16 K, with a maximum Tc-onset value of 15.11 K.

Bimetallic Ba(II)-Cr(III) and trimetallic Ba(II)-Ln(III)-Cr(III) (Ln(III) = Gd, Tb, Dy, Ho, Er, Yb, Y) coordination polymers formed by Cr(III)-containing building blocks with cyclopropane-1,1-dicarboxylate anions

The reaction of chromium(III) nitrate with Ba(cpdc) (H2cpdc = cyclopropane-1,1-dicarboxylic acid) in a ratio of 1:3 yielded a 1D coordination polymer {[Ba2Cr2(OH)2(cpdc)4(H2O)8]·5H2O}n (1) formed by binuclear units [Cr2(OH)2(cpdc)4]4− and a 3D polymer [Ba2Cr(cpdc)3(NO3)(H2O)6]n (2) constructed from tris-chelate blocks [Cr(cpdc)3]3−. The addition of rare-earth metal nitrates (Cr:Ln = 1:2) in this reaction led to the formation of a series of trimetallic 3D coordination polymers {[Ba3Ln2Cr4(cpdc)12(H2O)24]·8H2O}n (3Ln, Ln = Gd, Tb, Dy, Ho, Er, Yb, Y), in whose structures tris-chelate fragments [Cr(cpdc)3]3− are bound in layers by Ln3+ ions and, further, in a framework due to the coordination of Ba2+ ions. The crystal structures of 1, 2, and 3Gd were determined by single-crystal X-ray diffraction (XRD), and isostructurality of all the compounds in the series 3Ln was proved by powder X-ray diffraction (PXRD). DC-magnetic susceptibility measurements revealed weak ferromagnetic exchange interactions between Cr3+ ions in compound 1 (J = +0.74 cm−1). According to ac-magnetic susceptibility measurements, complexes 3Er and 3Y exhibit field-induced slow relaxation of magnetization. According to the data of simultaneous thermal analysis (STA) and differential scanning calorimetry (DSC) performed under Ar atmosphere, dehydration of the compounds obtained takes place in one (for 1 and 3Gd) or three stages (for 2). The initial temperature of the organic part degradation process decreases when moving from compound 1 containing dimerized bis-chelate fragments [Cr2(OH)2(cpdc)4]4− (330 °C) to compounds 2 (276 °C) and 3Gd (261 °C) based on tris-chelate units [Cr(cpdc)3]3−.

Temperature-sensitive polymer grafted with nano-SiO2 improves sealing and inhibition performance of shale water-based drilling fluid

Drilling fluid loss is an important factor restricting oil and gas production. The development of pores and micro-fractures in shale formations is the main cause of drilling fluid loss. In this study, silane coupling agent modified nano-SiO2 was used as the rigid core, and N-isopropylacrylamide and 2-hydroxyethyl methacrylate were used as the flexible outer shell. The temperature-sensitive blocking agent PKSHN was synthesized by inverse microemulsion polymerization method. PKSHN was analyzed and tested through Fourier transform infrared spectroscopy, simultaneous thermal analysis, transmission electron microscopy, dynamic laser scattering and other methods. The results show that PKSHN can achieve a hydrophilic/hydrophobic transition under the response temperature, with a median particle size of 189.35 nm, which can form a hydrophobic layer on the shale surface and reduce fluid intrusion into the shale formation. This study tested the performance of three drilling fluids with different densities by adjusting the amount of weighting agent. The results showed that the high-temperature and high-pressure filter losses of the three different densities of drilling fluids were all less than 10 mL. The addition of PKSHN can effectively reduce fluid loss. The rolling recovery experiment and linear expansion experiment show that after aging for 16 h at 150 °C, the rolling recovery rate is above 90 % and the linear expansion rate is below 7 %, indicating that the addition of PKSHN can effectively control the hydration expansion of shale.

Impact of Cations and Framework on Trapdoor Behavior: A Study of Dynamic and In Situ Gas Analysis.

Due to their distinct and tailorable internal cavity structures, zeolites serve as promising materials for efficient and specific gas separations such as the separation of /CO2 from N2. A subset of zeolite materials exhibits trapdoor behavior which can be exploited for particularly challenging separations, such as the separation of hydrogen, deuterium, and tritium for the nuclear industry. This study systematically delves into the influence of the chabazite (CHA) and merlinoite (MER) zeolite frameworks combined with different door-keeping cations (K+, Rb+, and Cs+) on the trapdoor separation behavior under a variety of thermal and gas conditions. Both CHA and MER frameworks were synthesized from the same parent Y-zeolite and studied using in situ X-ray diffraction as a function of increasing temperatures under 1 bar H2 exposures. This resulted in distinct thermal responses, with merlinoite zeolites exhibiting expansion and chabazite zeolites showing contraction of the crystal structure. Simultaneous thermal analysis (STA) and gas sorption techniques further demonstrated how the size of trapdoor cations restricts access to the internal porosities of the zeolite frameworks. These findings highlight that both the zeolite frameworks and the associated trapdoor cations dictate the thermal response and gas sorption behavior. Frameworks determine the crystalline geometry, the maximum porosities, and displacement of the cation in gas sorption, while associated cations directly affect the blockage of the functional sites and the thermal behavior of the frameworks. This work contributes new insights into the efficient design of zeolites for gas separation applications and highlights the significant role of the trapdoor mechanism.

Synthesis of transparent tin-doped indium oxide (ITO)-containing glass-ceramic coating by the sol-gel route for UV/NIR-shielding

Transparent glass-ceramic containing tin-doped indium oxide nano-crystalline phase was synthesized using the sol-gel method. The prepared sol, which was based on sodium aluminoborosilicate glass composition, was applied on soda-lime-silicate glass substrate through the dip-coating technique. Developing such glass-ceramics can offer several advantages, including reducing the total cost of production, enhanced chemical durability and a low-temperature synthesis process. The thermal behavior of the dried gels was investigated using simultaneous thermal analysis (STA), to determine the decomposition temperature of the nitrate salts in the gel, its glass crystallization temperature, and finally to optimize the heat treatment regime and optical properties as well. UV–Vis–NIR spectroscopy of the coated samples after heat treatment at 500 °C for 10 h revealed high visible transparency (T>70%) while indicating significant UV/NIR shielding, i.e. near zero and 10 % transmission, respectively. Phase analysis and crystallization behavior studies were conducted using XRD and FE-SEM to evaluate the morphology and size of the precipitated crystallites. According to the results, the optimum heating program for ITO crystallization was heating temperature and soaking time of 500 °C and 10 h, respectively. The undesirable crystalline phase of InBO3 was precipitated as the main crystalline phase by increasing the heat treating temperature to 550 °C. Furthermore, the glass structure was studied using FTIR spectroscopy demonstrating a highly polymerized glassy network for the coating. The effect of the precursors-to-solvent ratio during the synthesis process on the final optical properties was also investigated.

Microscopic Chemical Reaction Mechanism and Kinetic Model of Al/PTFE.

In order to study the microscopic reaction mechanism and kinetic model of Al/PTFE, a reactive force field (ReaxFF) was used to simulate the interface model of the Al/PTFE system with different oxide layer thicknesses (0 Å, 5 Å, 10 Å), and the thermochemical behavior of Al/PTFE at different heating rates was analyzed by simultaneous thermal analysis (TG-DSC). The results show that the thickness of the oxide layer has a significant effect on the reaction process of Al/PTFE. In the system with an oxide layer thickness of 5 Å, the compactness of the oxide layer changes due to thermal rearrangement, resulting in the diffusion of reactants (fluorine-containing substances) through the oxide layer into the Al core. The reaction mainly occurs between the oxide layer and the Al core. For the 10 Å oxide layer, the reaction only exists outside the interface of the oxide layer. With the movement of the oxygen ions in the oxide layer and the Al atoms in the Al core, the oxide layer moves to the Al core, which makes the reaction continue. By analyzing the reaction process of Al/PTFE, the mechanism function of Al/PTFE was obtained by combining the shrinkage volume model (R3 model) and the three-dimensional diffusion (D3 model). In addition, the activation energy of Al/PTFE was 258.8 kJ/mol and the pre-exponential factor was 2.495 × 1015 min-1. The research results have important theoretical significance and reference value for the in-depth understanding of the microscopic chemical reaction mechanism and the quantitative study of macroscopic energy release of Al/PTFE reactive materials.

Synthesis of Cu0.5Zn0.5-xNixFe2O4 nanoparticles as heating agents for possible cancer treatment

Magnetic mixed ferrites with high heating efficacy have attracted lots of attention as a complementary method for cancer treatment via magnetic hyperthermia therapy. In the present study, magnetic Cu0.5Zn0.5-xNixFe2O4 nanoparticles were synthesized via a sol–gel combustion method. The effects of nickel substitution (x = 0.1, 0.2, 0.3, 0.4 and 0.5) on the magnetic and structural properties of the produced nanoparticles were investigated. The produced magnetic nanopowders were studied via X-ray diffraction (XRD), scanning electron microscopy (SEM), simultaneous thermal analysis (STA), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and vibrating-sample magnetometry (VSM) techniques. The results showed that the saturation magnetization and coercivity of ZnCuFe2O4 nanoparticles were strongly affected by nickel substitution in the structure so that saturation magnetization decreased from 55.4 emu/g to 36.0 emu/g, whereas coercivity increased from 87.9 Oe to 156.4 Oe. In addition, saturation magnetization for the Cu0.5Zn0.4Ni0.1Fe2O4 sample increases from 55 to 58.1 emu/g with a rise in calcination temperature from 400 to 700 °C, respectively. The heating efficiency of the samples was investigated under different magnetic fields for magnetic hyperthermia therapy. The Cu0.5Zn0.4Ni0.1Fe2O4 sample exhibits a temperature increase from 37 °C to 49.5 °C during 10 min in the exposure of a magnetic field of 400 Oe and frequency of 200 kHz. The specific absorption rate value calculated for the Cu0.5Zn0.5-xNixFe2O4 nanoparticles was 53.1 W/g. With the increase in the viscosity of the environment, the heating efficiency of nanoparticles is reduced. Despite this decrease, the magnetic characteristics of nanoparticles remained strong enough to envision their usage as heating agents in magnetic hyperthermia.

Outstanding photocatalytic activity of a mechano-thermally synthesized Z-scheme BiFeO3- Fe2O3 heterostructure

In this study, α-Bi2O3 and α-Fe2O3 powder mixtures experienced a novel mechano-thermal procedure, which includes high-energy ball milling followed by heat treatment, resulting in the successful synthesis of a BiFeO3-Fe2O3 nanocomposite. Simultaneous thermal analysis (STA) and X-ray diffraction (XRD) showed that the formation and characteristics of BiFeO3-Fe2O3 nanocomposite are greatly influenced by the milling process, heat-treatment temperature, and the α-Bi2O3:α-Fe2O3 molar ratio. X-ray photoelectron spectroscopy (XPS) spectra confirmed the presence of Bi, Fe, and O, indicating the formation of the BiFeO3 phase. Field emission scanning electron microscopy (FESEM) analysis showed the development of plate-like microstructures in the BiFeO3 phase with an average thickness of 88 nm. Diffuse reflectance spectroscopy (DRS) indicated that the 20 h-milled nanocomposite with a molar ratio of α-Bi2O3:α-Fe2O3 (1:3) exhibited the lowest band gap of 2.38 eV after heat treatment at 750 °C. The reduction in photoluminescence (PL) peaks and increase in photocurrent in the above sample suggested a decrease in charge carrier recombination rate, leading to high photocatalytic activity of 85 and 42% for methylene blue (MB) and methyl orange (MO) degradation, respectively. The effect of various pH levels on the photocatalytic activity of both dyes was examined, with MO degrading by 94% in an acidic environment after 300 min of visible light exposure, while MB experienced similar degradation in an alkaline setting. The kinetics and mechanism of photocatalytic degradation were extensively studied using the Langmuir-Hinshelwood (L-H) model, revealing the significant role of hydroxyl radicals in photodegradation. A Z-scheme mechanism for charge transfer in the nanocomposite was postulated, drawing upon radical scavenging and Mott-Schottky experiments. The prepared photocatalyst showed excellent stability and reusability following a cyclic experiment.