Differential Thermal Analysis Studies Research Articles

Alumino-Silico-thermic synthesis of high purity ferroboron alloy and its characterization

High purity ferroboron (Fe–B) alloy is used as an alloying agent for making special grades of steels, Nd-Fe-B magnets etc. In this study, alumino-silico-thermic co-reduction of Fe2O3 and B2O3 was attempted to prepare high purity Fe–B. Extensive differential thermal analysis (DTA) studies were carried out to understand the reduction behaviour of Fe2O3 and B2O3 by Al and Si. DTA exothermic peaks indicated three step reduction of Fe2O3 (Fe2O3→Fe3O4→FeO→Fe) when reacted with Al and Si separately. B2O3–Si system did not show exothermic peaks while heating indicating sluggish or no reduction, however, B2O3–Al DTA peaks indicated two step reduction behaviour. Differential thermal analysis of Fe2O3–B2O3–Al–Si indicated completion of reduction of oxides, and formation of different intermediate phases. Specially designed reduction reactors were used to produce ferroboron alloy in bulk quantities. Thermal analysis results suggested that the formation of aluminium and silicon borides could be avoided using sub-stoichiometric amount of Al and Si, which was further confirmed from the bulk thermit product. Si acted as reducing agent as well as forming low melting slag comprising of Al(Si)–B–O type oxides. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and Particle Induced Gamma-ray Emission (PIGE) analysis confirmed the presence of 12 wt% boron in the alloy product with lower content (<1 %) of impurity elements like Al and Si. The relationship between the chemical homogeneity with the thermit process parameters was established. Microstructure and mechanical properties confirmed the formation of Fe2B and FeB phase in the thermit alloy.

An investigation of AlN nanoparticles by DTA and DTG methods

Differential thermal analysis (DTA) and differential thermal gravimetry (DTG) studies at different heating rates of were considered for AlN nanoparticles. The free Gibbs energy in the temperature range of 300÷1400 K is determined at 5, 10, 15 and 20 K/min heating rates. Experiments were separately carried out in both heating and cooling processes and obtained results were analyzed in detail. The enthalpy and entropy of the system composed of nano AlN particles at different thermal treatment rates were calculated (theoretical calculations were justified by experimental results). The values acquired from the experimental results were compared for all thermophysical parameters at different thermal treatment rates.

Lithium-ion Differential Thermal Analysis Studies of the Effects of Long-Term Li-ion Cell Storage on Electrolyte Composition and Implications for Cell State of Health

Li-ion cells being developed for long lifetime applications are often subjected to storage tests at various states-of-charge and various temperatures. Storage is interrupted from time to time for reference performance tests so that cell capacity and impedance can be checked. These reference performance tests give no information about any compositional changes that may have occurred in the electrolyte. Lithium-ion differential thermal analysis applied to cells after years of storage can be used to determine if the electrolyte has changed significantly due to unwanted reactions with the electrode materials or if little to no change has occurred. Here, Li-ion differential thermal analysis is used to study electrolyte changes in a more-or-less “yes/no” manner for single crystal NMC532/graphite cells stored between 3.67 and 4.3 V at 20, 40 and 55 °C for up to five years. Such measurements can be used to give confidence about lifetime predictions. Several such cells are detailed here, with correlation between degree of cell degradation and degree of change in electrolyte composition. Relationships are shown between degradation and evolution of state of electrolyte in elevated temperature and voltage storage experiments.

Optimization of Electrical Properties of Nanocrystallized Na3M2(PO4)2F3 NASICON-like Glasses (M = V, Ti, Fe)

Recently, an interest in NASICON-type materials revived, as they are considered potential cathode materials in sodium–ion batteries used in large-scale energy storage. We applied a facile technique of thermal nanocrystallization of glassy analogs of these compounds to enhance their electrical parameters. Six nanomaterials of the Na3M2(PO4)2F3 (M = V, Ti, Fe) system were studied. Samples with nominal compositions of Na3V2(PO4)2F3, Na3Ti2(PO4)2F3, Na3Fe2(PO4)2F3, Na3TiV(PO4)2F3, Na3FeV(PO4)2F3 and Na3FeTi(PO4)2F3 have been synthesized as glasses using the melt-quenching method. X-ray diffraction measurements were conducted for as-synthesized samples and after heating at elevated temperatures to investigate the structure. Extensive impedance measurements allowed us to optimize the nanocrystallization process to enhance the electrical conductivity of cathode nanomaterials. Such a procedure resulted in samples with the conductivity at room temperature ranging from 1×10−9 up to 8×10−5 S/cm. We carried out in situ impedance spectroscopy measurements (in an ultra-high-frequency range up to 10 GHz) and compared them with thermal events observed in differential thermal analysis studies.

Physicochemical Analytical Studies on Yttrium‐Doped Triglycine Sulfate Single Crystals

Single crystals of pure triglycine sulfate (TGS) and yttrium-acetate (0.5 mol%)-doped triglycine sulfate (YTGS) crystals are synthesized and the crystals are grown from aqueous solution by slow evaporation solution growth method. The grown crystals are subjected to single crystal and powder X-ray diffraction studies to identify the morphology and structure. Both the grown crystals are packed in a monoclinic crystal system and the lattice parameters of YTGS crystal are a = 9.138 Å, b = 12.72 Å, and c = 5.728 Å, whereas the doped TGS are, a = 9.134 Å, b = 12.61 Å, and c = 5.723 Å. The lattice parameters are slightly distorted due to the incorporation of yttrium ion into the lattice sites of the TGS crystal. The thermal stability of the grown crystals is investigated by differential thermal analysis (DTA) and thermogravimetric studies. DTA curve shows a lower decomposition temperature for YTGS crystal than for pure TGS crystal. The functional groups of the grown crystals are identified by Fourier transform infrared spectral studies. The surface morphology of the crystals is examined by scanning electron microscopy. Dielectric studies are carried out to identify the phase transition temperature and to find the dielectric constant of the YTGS crystals.

Thermal and thermoluminescence properties of LiF-BaO-P2O5 glass

The set of six fluorophosphate glasses were obtained to measure the effect of composition on their thermal and luminescence properties. It was found that the phosphate network can accept much more lithium fluoride as compared to silica and borate glasses. The differential thermal analysis study shows a significant increase of thermal stability and decrease of the crystallization with higher content of lithium fluoride. Simultaneously, a gradual increase in the intensity of thermoluminescence was observed as well as linearity of the thermoluminescence response. We correlated the observed effects with the structural changes based on fourier-transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance analysis.

Structural phase transition, optical and electrical properties of the hybrid material [(C2H5)4N]2ZnI4

The bis (tetra-ethylammonium) tetraiodo-zincate (II) was prepared by slow evaporation an aqueous stoichiometric mixture of tetra-ethylammonium iodide and zinc iodide at room temperature. This compound has been characterized by X-ray diffraction (XRD), thermal analysis, UV–vis spectroscopy and complex impedance spectroscopy. Single crystal X-ray diffraction analysis shows that the title compound crystallizes in the tetragonal system with space group P4¯21m.The differential thermal analysis (DTA) and temperature-controlled X-ray diffraction study reveal a reversible first order phase transition at about 444 ​K between low temperature-tetragonal and high temperature-orthorhombic forms of [(C2H5)4N]2ZnI4. Below 444 ​K, the low temperature form exhibits two linear regimes of thermal expansion with a change in the slope around 373 ​K which is ascribed to a second-order phase transition. The diffuse reflectance indicates the existence of an optical direct transition with the band gap energy is equal to 3.9 ​eV. The spectra of complex impedances obtained in the temperature range from 403 to 468 ​K were modelled by a combination of R//CPE elements. . A change of conduction regime around 444 ​K is noted in the variation of the Ln (σDC.T) versus reciprocal temperature. In both regimes, the conductivity obeys the Arrhenius law with activation energies of 1.37 ​eV in regime I and 2.37 ​eV in regime II. Frequency dependence of the AC conductivity followed the universal Jonscher's power law.

PHASE TRANSITION STUDIES OF CHOLESTERYL PALMITATE, CHOLESTERYL DECANOATE AND THEIR MIXTURES USING DIELECTRIC, EPR AND DTA TECHNIQUES

The phase transition of two liquid crystalline materials, namely cholesteryl palmitate and cholesteryl decanoate and their mixtures (by weight)are studied using dielectric, Electron paramagnetic resonance (EPR) and differential thermal analysis (DTA) techniques. From the dielectric measurements, the phase transition temperatures were determined from the discontinuities in the curve between dielectric constant and temperatures for all the samples investigated. Further, since mixing of two liquid crystals modifies the transition of phases, the measurements were carried out on the mixtures of the two liquid crystals. Order parameter for each sample was calculated at varying temperatures by measuring the hyperfine splitting of three line EPR spectrums. The discontinuities in the curve between order parameter and the temperature again indicated the phase transition of the liquid crystals and their mixtures. A DTA study on these samples was also carried out in order to probe further their transitional behaviour. The DTA records of both the liquid crystals and their mixtures support the transition behaviour observed from the dielectric and EPR measurements.

Fabrication, Characterization, Ion-Exchange studies and binary separation of Polyaniline/Ti(IV) iodotungstate composite Ion-Exchanger for the treatment of water pollutants

There has been substantial research on the ion-exchange media for the remediation of waste water containing heavy metal ions. This fact has led efforts to develop new and advanced composite ion-exchangers for the removal of toxic heavy metal ion for environmental remediation. Ion-exchange technique is one of the eco-friendly and economically viable techniques. The conducting polymer-based composites have been synthesized by using simple sol–gel method and characterized by using various techniques including Fourier Transform- Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis - Differential Thermal Analysis (TGA-DTA) and X-Ray Diffraction (XRD) studies. The ion-exchange materials were explored for different physico-chemical properties such as ion-exchange capacity, effect of eluent concentration, elution behavior, pH titration, thermal and chemical stability were also carried out to exploit their ion-exchange capabilities. The distribution coefficient studies of composite ion-exchanger were investigated for different metal ions in different solvent systems. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ion Pb(II). The selectivity of the composite for Pb2+ in 0.1 M HNO3 medium along with their reproducible quantitative separation from binary mixture. Therefore, the newly synthesized ion-exchangers can be used as potential ion-exchange materials for environmental remediation. Comparative study of the ion-exchange properties of PANI/Ti(IV) iodotungstate ion-exchanger with Ti(IV) iodotungstate (inorganic ion-exchanger) has been done.

Age hardening heat treatment behavior of as-cast Mg–Zn–Al alloys

Magnesium alloys have generated renewed interest as a light alloys; replacing some conventional structural materials for weight reduction in applications like aerospace, automotive and electronics industries. In interior components and powertrains, cast alloys are widely used and represent more than 99% of magnesium alloys used today, whereas only a few wrought products are used. Mostly in automotive applications, Mg-engine block can noticeably reduce the weight and consequently its fuel consumption and environmental impact. Due to solid-state precipitates, these alloys are strong in nature and are produced by an age-hardening heat treatment process. In the present work the age hardening behavior of the as cast Mg–Zn–Al alloys (ZA85 alloy) in the composition of 8 wt. %Zn, 5 wt. %Al has been investigated. Through the differential thermal analysis (DTA) studies, it has been found out that dissolution temperature of ternary eutectic precipitates is present in the alloy. Based on the DTA results, the as cast samples have been solutionised at 360 °C temperature for different intervals of time. Solutionising time has been optimized from the enthalpy values of un-dissolved precipitates. The solution treated samples have been then aged at temperature of 180° C for different time intervals. From the peak hardness values, the ageing conditions have been optimized.

Theoretical and experimental investigations of new bis (amino triazole) schiff base ligand: Preparation of its UO2(II), Er (III), and La (III) complexes, studying of their antibacterial, anticancer, and molecular docking

UO2(II), Er (III), and La (III) complexes were prepared from new bis (amino triazole) Schiff base ligand. The ligand was synthesized by condensation of 1,3‐bis(4‐amino‐5‐phenyl‐1,2,4‐triazol‐3‐ylsulfanyl)propane with benzaldehyde. The structure of the prepared compounds was confirmed by some spectroscopic tools such as1H‐NMR, UV‐Vis, and IR, as well as molar conductance, mass spectrometry, elemental analysis, thermogravimetric analysis (TG), differential thermogravimetric (DTG), and differential thermal analysis (DTA) studies. The data revealed coordination of the complexes with tetradentate Schiff base. All complexes were octahedral. Computational studies for the prepared ligand by using DFT/B3LYP method were reported. The theoretical results described its bond lengths, angles, and dipole moment, and other parameters were calculated. The theoretical studies were supported the experimental data of the ligand and confirmed its successful preparation. Also, their antibacterial activities against four types of bacteria species (Pseudomonas aeruginosa,Escherichia coli,Bacillus subtilis, andStaphylococcus aureus) were investigated. The prepared complexes were biologically active compounds. The synthesized compounds were estimated for their anticancer activities against two cell lines (MCF‐7 and HepG2). The lowest IC50values were 17.6 and 23 μM for uranyl complex against MCF‐7 and ligand against HepG2 cell lines, respectively, which make them very important materials as anticancer drugs in the future researches. Finally, molecular docking studies were checked up for all prepared compounds with different protein receptors (3HB5 and 2GYT) to confirm their anticancer activities data.

Determining the temperatures to which the bone was heated in archaeological contexts. Distinguishing between boiled and grilled bones

A study carried out in fresh cow (Bos taurus) cortical-femur bones which allows determining the maximum annealing temperature to which a bone was subjected is shown. It is focused on temperatures near the ones used in culinary activities. Mechanical spectroscopy, optical microscopy, differential thermal analysis and thermogravimetry studies are used in the present work. The study takes into account the behaviour of the thermal denaturation processes from the remnant collagen as a function of temperature. The survey of the relaxation process related to the triple helix to random coil transition from the residual collagen which occurs at 510 K/237 °C, is proposed as a potentially useful tool for determining that the bone was not previously heated above this temperature. In addition, by using mechanical spectroscopy a procedure for discriminating between grilled- and boiled-bones is shown. Likewise, a reference chart of the thermodynamic states of denaturation of collagen in the bone as a function both of temperature and cooking mode is reported. The relationships between the denaturation stages and the responses from mechanical spectroscopy and differential thermal analysis are also shown.

Mössbauer and differential thermal analysis studies of iron alkali lead-phosphate glasses

This work reports on the effect of the increment of Fe2O3 in a network of phosphate glasses involving Al2O3, Na2O and PbO by DTA and Mössbauer techniques. The analysis of Mössbauer suggests oxidation of Fe2+ ions in the distorted bipyramidal to Fe3+ in the same site. This procedure creates non-bridging oxygens joined with Fe2+ octa that weakens the phosphate network whenever the Fe2O3 content increases. The thermal parameters of the phosphate network will be affected by this weakness. Thus, both the glass transition temperature (T gl ) and the crystallization peak temperature (T cp ) on the one hand and the activation energies for glass transition E gl and for crystallization (E gl and E cp ) on the other hand will decrease as a function of Fe2O3. This decrease will be discussed following Lasocka’s relationships that present a good correlation between T gl and T cp . Furthermore, the glass transition temperature (T gl ) was correlated with the glass fragility (m) and with the elastic parameters of the phosphate network such as the bulk (K) and shearing (G) moduli.

Synthesis, characterization, refractive index-bandgap relations, and optical nonlinearity parameters of CuI/PVOH nanocomposites

In the current work, CuI nanoparticles (NPS) were synthesized at low temperatures via facile microwave-assisted technique, while the casting method was used to prepare nanocomposite systems. The structure of NPS powder and nanocomposites films were examined by XRD (Diffraction of X-ray) and EDAX spectra (Energy Dispersive Analysis of X-ray). The particle size and the sample’s morphology were studied by HR-TEM and SEM (Scanning electron microscopy). DTA (Differential thermal analysis) study shows that the thermal stability of CuI(NPS)/PVOH nanocomposites higher than that of pure PVOH film. The band-tail and bandgap energy were influenced by the CuI(NPS) percentage in the PVOH matrix. The improvement in the linear optical parameters such as absorption index, dielectric constant, and refractive index are noticed with raising the doping ratio. The refractive index (n) was calculated as a function of the energy gap by different formulas. The average value of n increased from 2.06 to 2.15 with increasing the NPS percentage. The nonlinear optical parameters χ(1), χ(3) and n2 are varying in the range of 0.258 e.s.u to 0.291 e.s.u, 0.762 × 10–12 e.s.u to 1.225 × 10–12 e.s.u, and 1.39 × 10−11 e.s.u to 2.14 × 10−11 e.s.u, respectively. Moreover, the dielectric constant (ε∞) varies from 4.25 to 4.66. The ability of the present samples to decrease the laser beams power, with wavelengths 632.8 nm and 533 nm, was detected. The enhancement in the optical properties of the nanocomposites with increasing the CuI(NPS) concentration recommends that the synthesized systems are suitable for commercial optical cut-off and various optical device applications.

Preparation and characterization of nanoboron by cryo-milling

Cryo-milling of coarse micron grade elemental boron powder was investigated for possible generation of nanosized boron powder. Process parameters were optimized for the least contamination and least particle size. The as-milled powders were characterized by scanning and transmission electron microscopy (SEM/TEM) and x-ray diffraction (XRD) for powder morphology, average particle size, and phase analysis. The particle size and surface area were also estimated using dynamic laser scattering (DLS) and BET techniques to correlate with the performance of the material. Thermo-gravimetric and differential thermal analysis (TG-DTA) studies were performed to ascertain mass change and energy release in unmilled and milled powder. The average particle size of boron powder after 9 h of cryo-milling was<100 nm. The cryo-milled powder was made air-stable and dispersible in JP10 fuel by coating it with ligand through the mechanical milling method. The TOPO (tri-n-octyl phosphine oxide) coated nano boron powder exhibited dispersion stability for a week.

Self-heating evaluation of superparamagnetic MnFe2O4 nanoparticles for magnetic fluid hyperthermia application towards cancer treatment

In the vision of hyperthermia application, high quality superparamagnetic MnFe2O4 nanoparticles (NPs) were synthesized via low cost and environment-friendly co-precipitation method. Thermogravimetric and differential thermal analysis studies confirmed the ferritization temperature at 900 °C. The formation of crystals with a single-phase cubic spinel structure with the Fd3m space group has been confirmed by XRD analysis. SEM-EDX result reveals that the spherical nature of grains with some agglomeration and elemental analysis helps to calculate the atomic percentage of each detected element. An average particle size (~25 nm) was determined by TEM analysis. VSM analysis shows that saturation magnetization (Ms) increases with decreasing temperature in the range 54.18–59.67emu/g at room temperature (300K) to low temperature (5K), respectively, which displays temperature change affects the saturation magnetization and coercivity. FC-ZFC measurements indicated a blocking temperature of NPs around 97.17K. The induction heating study was performed on MnFe2O4 magnetic NPs at 4 kA/m AC magnetic field amplitude and 280 kHz frequency for application in magnetic hyperthermia. The result demonstrates that the heating ability of MnFe2O4 magnetic NPs can be achieved hyperthermia temperature (42 °C) at small content of 0.4 g/mL within 260sec-time duration, which confirms that the prepared material can be used as a heating agent in magnetic hyperthermic treatment. The specific absorption rate (SAR) was found at 217.62 W/g, the obtained result is superior to the previous reports. The obtained results show that the newly synthesized superparamagnetic NPs can act as a promising candidate for hyperthermia therapy due to its high heat-generating capability at lower concentrations with less time period.

Graphene based ceria nanocomposite synthesized by hydrothermal method for enhanced supercapacitor performance

Reduced graphene oxide – cerium oxide (rGO-CeO2) nanocomposite is prepared by simple hydrothermal method for enhanced charge storage supercapacitor performance. The prepared nanocomposite is characterized by various techniques, such as X-ray diffraction (XRD), Fourier Transform – Raman Spectra (FT-Raman), Field Emission - Scanning Electron Microscope (FE-SEM), High Resolution –Transmission Electron Microscope (HR-TEM), Thermo-gravimetric and Differential Thermal Analysis (TG-DTA), Cyclic Voltametric (CV), Galvanostatic Charge/Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) studies to understand its morphology, composition, thermal stability and charge storage efficiency as electrode material. The nanocomposite formation is confirmed with FE-SEM and HR-TEM images where the ceria is anchored on the surface of the graphene sheets and the interplanar distances are observed as fringes. The Energy Dispersive Analysis of X-Ray (EDAX) has provided substantial evidence for the nanocomposite formation with the elemental composition. The maximum specific capacitance is measured as 280 F/g using GCD studies. The surface area of the nanocomposite is determined using the Brunauer-Emmett-Teller (BET) analysis.

Phase Equilibria in the System Ag-Cu-Si

The ternary alloy system Ag-Cu-Si was investigated in detail for the first time. The phase diagram was analysed by means of light optical microscopy, powder x-ray diffraction, differential thermal analysis (DTA) and scanning electron microscopy in combination with energy dispersive x-ray spectroscopy. The complete isothermal section at 650 °C was studied experimentally, and several additional samples were studied in order to obtain insight into phase equilibria with the high-temperature phases of the binary Cu-Si system. DTA studies in two vertical sections were used to determine ternary invariant phase reactions and to construct the ternary reaction scheme (Scheil diagram). A liquidus surface projection was constructed by combining these data with microstructure analysis of selected as-cast samples.

Binuclear copper(II) complexes: Synthesis, structural characterization, DNA binding and in silico studies

Two new binuclear Cu(II) complexes represented by the general formula {(dmso)Cu(?-L)4Cu(dmso)} (1) and {(Phen)(L)Cu(?-L)2Cu(L)(Phen)} (2) where dmso = dimethyl sulphoxide, L = 2-bromophenyl acetate and Phen = = 1,10-phenanthroline have been synthesized, isolated quantitatively and characterized by UV/Vis and FT-IR spectroscopic techniques, thermogravimetry/ /differential thermal analysis and X-ray single crystal XRD studies. Complex 1 is paddlewheel with 1,2-O,O-bridging while 2 has 1,1-O-bridging. The values of the intrinsic binding constants with DNA were found out to be 2.0?103 and 1.1?103 M-1, respectively for compound 1 and 2. The mode of interaction of complexes with DNA was also evaluated through computational study by molecular docking (in silico) study using molecular operating environment (MOE) software. The synthesized complexes are structurally as well as biologically important.

A combined Raman, Fourier transform infrared, and X‐ray diffraction study of thermally treated nesquehonite

AbstractNesquehonite synthesized by mixing MgCl2·6H2O and Na2CO3 at T 25°C, was thermally treated at various temperatures (170°C, 200°C, 295°C, 350°C, and 390°C), based on thermal analysis study of raw nesquehonite. The mineral phases formed at each temperature were studied by means of Raman microspectroscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. After thermal treatment of raw nesquehonite above 295°C, its dominant Raman peak at 1,100 cm−1, which corresponds to the v1 CO32− antisymmetric stretching vibrations, exhibits broadening and upshift of up to 10 cm−1, whereas the Raman peaks at 707 cm−1, at 770 cm−1, at 1,425 cm−1, and at 1,710 cm−1 disappear, and new Raman peaks arise at 1,282 cm−1 and at 1,386 cm−1. The latter have been attributed to the decomposition of HCO3−, in accordance with the Fourier transform infrared spectroscopy study. According to the differential thermal analysis study, water of crystallization is lost in two steps until 295°C; therefore, the phase studied above this temperature corresponds to Mg (HCO3)(OH). The Raman peak at 3,550 cm−1 assigned to the existence of OH−, exhibits weakening after thermal treatment. Our results corroborate a Mg (HCO3)OH·2H2O nesquehonite formula.