Thermogravimetric And Differential Thermal Analysis Research Articles

Nd and Sc co-doped BiFeO3 nanopowders displaying enhanced ferromagnetism at room temperature

We have developed a novel synthetic route for the preparation of single phase NdxBi1−xFe0.95Sc0.05O3 (NBFSO) nanopowder materials by a surfactant-assisted combustion-derived method. Rietveld fitting of the Powder X-ray diffraction data showed the nanopowder structure evolves from a distorted rhombohedral BiFeO3 crystalline structure (R3c, x=0) to a orthorhombic structure (Pbnm, x=0.10). Differential thermal analysis and thermogravimetric analysis (DTA/TGA) showed a crystallization temperature of 200°C. Transmission electron microscopy (TEM) images revealed the presence of clusters formed by fine nanoparticles less than 60nm in diameter. From Raman spectroscopy, the change from rhombohedral structure to cubic structure was observed by a drastic intensity reduction of the A1−2 and A1−3 Raman modes, with the A1−1 and A1−2 modes gradually merging together, indicating the merge of the orthorhombic phase. Despite the antiferromagnetic nature of bulk BiFeO3, the NBFSO nanopowders obtained displayed a ferromagnetic hysteresis loop, with coercivities of 0.08T and remanent magnetizations of 0.65–4.05Am2/kg when measured at room temperature. The increasing and uncompensated spins at the surface of nanoparticles and the canted internal spin by the tilt of FeO6 octahedral units and the structure transition appear to be the main reason for observed this ferromagnetic behavior.

Synthesis and Characterization of Perovskite Oxides LaAl1−x Ni x O3−δ (0 ≤ x ≤ 0.6) via Co-precipitation Method

Our contribution has focused on the synthesis and characterization of nickel-containing LaAlO3 perovskite, LaAl1−x Ni x O3−δ (0 ≤ x ≤ 0.6) by a co-precipitation method. Nano-powders were successfully synthesized using nitrate salts of lanthanum, aluminium and nickel as cations precursors and sodium hydroxide such as base precipitant by this method and calcined at low temperatures. They were characterized by several techniques: Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscopy and electrochemical measurements. Thermal analysis shows that the crystallization temperature of the La (Al, Ni) O3−δ precursor gels are estimated as 780 °C by TG–DTA. The XRD patterns of the precursor gels calcined at 700 °C for 6 h have a perovskite structure and the presence of crystalline impurities is not found. The microstructure and morphology of the compounds show that the particles are nearly spherical in shape and are partially agglomerated. Electrochemical measurements indicate that the catalytic activity is strongly influenced by lanthanum doping. The highest electrode performance is achieved with large nickel content.

Synthesis and microstructure of La1−xCaxCoO3 nanoparticles and their catalytic activity for CO oxidation

Perovskite nanoparticles of La1−xCaxCoO3 (x = 0, 0.2, 0.3, 0.5) were synthesized by the combustion method using polyvinyl alcohol (PVA) and corresponding metal nitrates. Microstructure of samples was characterized by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) combined with x-ray diffraction (XRD). The nanoparticles were characterized by thermogravimetric and differential thermal analysis (TG-DTA) and BET (Brunauer–Emmet–Teller). A high surface area (15–21 m2 g−1) at low temperature (600 °C) of samples was obtained. The optimal preparative conditions were PVA/metals 2:1 by mole, pH = 3 and 80 °C for gel formation. Perovskites exhibit a good catalytic activity in total oxidation of CO at the low temperature (<250 °C) of reaction.

ELUCIDATING CHARACTERISTICS OF GEOPOLYMER WITH SOLAR PANEL WASTE GLASS

This study examined the characteristics of geopolymer with solar panel waste glass. After 28 days of curing, the compressive strengths of the geopolymer samples containing 10 mass % and 20 mass % solar panel waste glass were 63.3± 1.8 and 49.1 ± 2.2 MPa, respectively. The geopolymer sample with 10% solar panel waste glass exhibited a stronger reaction than that with 20% solar panel waste glass, and the strength decreased as the amount of solar panel waste glass increased. Thermo-gravimetric and differential thermal analysis (TG/DTA) results showed that the mass loss of geopolymer after heating declined as the amount of solar panel waste glass increased. The principal peaks in the Fourier transformation infrared spectroscopy (FTIR) spectra correspond to the Si-O-Al bond in geopolymer. Scanning electron microscopy (SEM) observations indicated that the microstructures of the stronger samples were more homogeneous, and the microstructures of geopolymer with 10% solar panel waste glass did not exhibit substantial deterioration. The experimental results indicate that solar panel waste glass has the potential to serve as a partial replacement of metakaolinite and exhibits favorable mechanic characteristics.

A Salt‐Assisted Combustion Method to Prepare Well‐Dispersed Octahedral MnCr2O4 Spinel Nanocrystals

Well‐dispersed nanocrystalline MnCr2O4 was prepared by a salt‐assisted combustion process using low‐toxic glycine as fuel and Mn(NO3)2 and Cr(NO3)3·9H2O as raw materials. The obtained products were characterized by X‐ray Diffraction (XRD), Fourier Transform Infrared (FT‐IR) spectroscopy, Raman spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The fabrication process was monitored by thermogravimetric and differential thermal analysis (TG‐DTA). The phase formation process was detected by XRD, and MnCr2O4 single phase with high crystallinity was formed at 700°C. TEM and SEM images revealed that the products were composed of well‐dispersed octahedral nanocrystals with an average size of 80 nm. Inert salt‐LiCl played an important role in breaking the network structure of agglomerated nanocrystallites.

Non-Isothermal Degradation of Vitamin C by Simultaneous Thermogravimetric and Differential Thermal Analysis

The non-isothermal degradation process of Vitamin C (Galenika, Serbia) was investigated by simultaneous thermogravimetric and differential thermal analysis (TG-DTA), in the temperature range from an ambient one up to 650°C. The scope of presented work is toward stability of active pharmaceutical substance – ascorbic acid and calculation of all relevants kinetics parameters: activation energy (Ea), pre-exponential factor (A) and half-time (t1/2) for stability assesment in explored formulation. It was established that the degradation proceeds through five degradation stages (designated as I, II, III, IV and V), which involve: the dehydration, the melting of ascorbic acid, as well as the decomposition of excipients present: microcrystalline cellulose, D-glucose, carboxymethylcellulose, magnesium stearate , lactose and corn starch. During thermal degradation, all excipients increase their thermal stability and some kind of solid-solid and/or solid-gas interaction occur. The kinetic parameters and reaction mechanism was determined for the II stage, where decomposition of ascorbic acid happened using powerfull kinetic software KINETICS05. Two approaches were used: isoconversional and modell fitting method. It was concluded that degradation of ascorbic acid is best described with N-th order model with Ea= 139.550kJ/mol, A= 1.9689∙1013s-1 and n=1.2132.

Highly Efficient Iodine Capture by Layered Double Hydroxides Intercalated with Polysulfides

We demonstrate strong iodine (I2) vapor adsorption using Mg/Al layered double hydroxide (MgAl-LDH) nanocomposites intercalated with polysulfide (Sx2–) groups (Sx-LDH, x = 2, 4, 6). The as-prepared LDH/polysulfide hybrid materials display highly efficient iodine capture resulting from the reducing property of the intercalated polysulfides. During adsorption, the I2 molecules are reduced to I3– anions by the intercalated [Sx]2– groups that simultaneously are oxidized to form S8. In addition to the chemical adsorption, additional molecular I2 is physically captured by the LDH composites. As a result of these parallel processes, and despite their very low BET surface areas, the iodine capture capacities of S2-LDH, S4-LDH, and S6-LDH are ∼1.32, 1.52, and 1.43 g/g, respectively, with a maximum adsorption of 152% (wt %). Thermogravimetric and differential thermal analysis (TG-DTA), energy dispersive X-ray spectroscopy (EDS), and temperature-variable powder X-ray diffraction (XRD) measurements show the resulting I3– ions that intercalated into the LDH gallery have high thermal stability (≥350 °C). The excellent iodine adsorption performance combined with the facile preparation points to the Sx-LDH systems as potential superior materials for adsorption of radioactive iodine, a waste product of the nuclear power industry.

Synthesis, effect of γ-ray and electrical conductivity of uranium doped nano LiMn2O4 spinels for applications as positive electrodes in Li-ion rechargeable batteries

Abstract LiMn2O4 is an attractive candidate cathode material for Li-ion rechargeable batteries, but it suffers from severe capacity fading, especially at higher temperature (55 °C) during charging/discharging processes. Recently, many attempts have been made to synthesize modified LiMn2O4. In this work, a new study on the synthesis of pure and U4+-doped nano lithium manganese oxide [LiMn2−x UxO4, (x = 0:00, 0.01, 0.03)] via solid-state method was introduced. The synthesized LiMn1:97U0:03O4 was irradiated by γ-radiation (10 and 30 kGy). The green samples and the resulting spinel products were characterized using thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared (IR), and scanning electron microscopy (SEM) measurements. XRD and SEM studies revealed nano-sized particles in all prepared samples. Direct-current (DC) electrical conductivity measurements indicated that these samples are semiconductors and the activation energies decrease with increasing rare-earth U4+ content and γ-irradiation. ΔEa equals to 0.304 eV for LiMn1:99U0:01O4, ΔEa is 0.282 eV for LiMn1:97U0:03O4 and decreases to ΔEa = 0:262 eV for γ-irradiated LiMn1:97U0:03O4 nano spinel. The data obtained for the investigated samples increase their attractiveness in modern electronic technology.

Preparation of Nanoparticulate ErFeO&lt;sub&gt;3&lt;/sub&gt; by Microwave Assisted Process and its Photocatalytic Activity

Using Er (NO3)3·5H2O and Fe (NO3)3·9H2O as major materials, the ErFeO3 nanoparticles were prepared by successive microwave processing and high temperature calcination. The samples were characterized by thermogravimetric and differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). It was found that the single phase ErFeO3 can be obtained through the calcination of microwave processed ErFeO3 precursors at 800°C, and the resulting product was approximation flake of 20-80 nm. The visible-light photocatalytic activity of ErFeO3 nanoparticles was investigated in experimental simulation wastewater containing 10 mg/L methyl orange (MO). The results show that ErFeO3 nanoparticles appear high photocatalytic activity for the decomposition of MO under visible-light irradiation.

One-Step Preparation of Nanoparticulate TbFeO&lt;sub&gt;3&lt;/sub&gt; by Microwave Process and its Visible-Light Photocatalytic Activity

TbFeO3nanoparticles were synthesized using Tb4O7and Fe (NO3)3·9H2O as the main raw material by a one-step microwave process. The prepared nanoparticles were characterized by thermogravimetric and differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). XRD and SEM demonstrate the successful synthesis of single phase TbFeO3and an average grain size of 40-100 nm in diameter. The single phase structure of TbFeO3was yet maintained after calcination at 800 °C. The photocatalytic experiment shows the high visible-light photocatalytic activity for the decomposition of methyl orange.

RKKP bioactive glass-ceramic material through an aqueous sol-gel process

In this work, the synthesis of RKKP bioactive glass composition by an aqueous sol-gel method is reported. A complete and systematic characterisation of the produced material was carried out. Characteristic functional groups were detected by Fourier transform infrared (FT-IR) spectroscopy, the thermal behaviour was investigated by simultaneous thermogravimetric and differential thermal analysis (TG-DTA), crystallisation kinetics and phase evolution were followed by X-ray diffraction (XRD) analyses. The microstructure of RKKP pellets thermally treated at properly selected temperatures was investigated by means of Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-Ray Spectrometry (EDS). Thermal dilatometry (peak temperature of 1100°C) was performed on bars pressed at 400MPa; final densities and microstructures were also evaluated. The expected glass-in-glass phase separation and carbonation induced by shelf-aging of the powders in common atmosphere were experimentally demonstrated. After thermal treatment at high temperature, the RKKP pellets experienced a drastic microstructure evolution, developing a highly porous matrix, in agreement with the de-densification phenomenon detected by dilatometry.

Characterization and magnetic properties of Nd Bi1−Fe0.95Co0.05O3 nanopowders synthesized by combustion-derived method at low temperature

Nd x Bi 1− x Fe 0.95 Co 0.05 O 3 ( x =0, 0.05, 0.10, 0.15) nanopowders were prepared by a combustion-derived method. The Rietvelt fitting of the X-Ray diffraction data from the Nd x Bi 1− x Fe 0.95 Co 0.05 O 3 (NBFCO) powders showed nanopowders with rhombohedral BiFeO 3 crystalline structure (R3c) for x ≤10 and a partial structural transition to orthorhombic phase (Pnma) for x =0.15. The differential thermal analysis and thermogravimetric analysis (DTA/TGA) showed a crystallization temperature of 180 °C. Transmission electronmicroscopy (TEM) images revealed that the NBFCO nanopowders were composed of fine particles under 60 nm. From Raman spectroscopy , a band of disordered anion lattice was observed at 653 cm −1 . In spite of the antiferromagnetic nature of bulk BiFeO 3 , the NBFCO nanopowders obtained displayed a ferromagnetic hysteresis loop, with coercivity about 0.1 T and remanent magnetization of 1.02–4.33 A m 2 /kg were obtained at room temperature. This ferromagnetic behavior is due to increasing and uncompensated spins at the surface and the canted internal spin by the tilt of FeO 6 octahedral units. We have developed a novel synthetic route for the preparation of ferromagnetic BFO-derived nanopowder materials by a surfactant-assisted combustion-derived method. • The structure of materials obtained is studied. • A new synthesis method was proposed to obtain ferrimagnetic–ferromagnetic BiFeO 3 nanoparticles. • Synthesis temperature does not exceed 200 °C. • The obtained nanoparticles have sizes less than 52 nm.

134 - Ascorbic Acid Improves Hyperoxia-Compromised Host Defense againstPseudomonas Aeruginosa Infection

NdxBi1−xFe0.95Co0.05O3 (x=0, 0.05, 0.10, 0.15) nanopowders were prepared by a combustion-derived method. The Rietvelt fitting of the X-Ray diffraction data from the NdxBi1−xFe0.95Co0.05O3 (NBFCO) powders showed nanopowders with rhombohedral BiFeO3 crystalline structure (R3c) for x≤10 and a partial structural transition to orthorhombic phase (Pnma) for x=0.15. The differential thermal analysis and thermogravimetric analysis (DTA/TGA) showed a crystallization temperature of 180 °C. Transmission electronmicroscopy (TEM) images revealed that the NBFCO nanopowders were composed of fine particles under 60 nm. From Raman spectroscopy, a band of disordered anion lattice was observed at 653 cm−1. In spite of the antiferromagnetic nature of bulk BiFeO3, the NBFCO nanopowders obtained displayed a ferromagnetic hysteresis loop, with coercivity about 0.1 T and remanent magnetization of 1.02–4.33 A m2/kg were obtained at room temperature. This ferromagnetic behavior is due to increasing and uncompensated spins at the surface and the canted internal spin by the tilt of FeO6 octahedral units. We have developed a novel synthetic route for the preparation of ferromagnetic BFO-derived nanopowder materials by a surfactant-assisted combustion-derived method.

The modification of lanthanum‐exchanged montmorillonite with anionic surfactants to enhance the thermal stability of polyvinyl chloride

ABSTRACTA series of thermally stable lanthanum organic montmorillonites (La‐OMMTs) were successfully prepared by modifying Na‐MMT with anionic surfactants and lanthanum chloride. Fourier transform infrared spectroscopy and X‐ray diffraction indicated that the anionic surfactants resided in the interlayer spaces and expanded the MMT basal spacing from 1.23 nm to 3.3 nm. Thermogravimetric and differential thermal analysis (TG/DTA) results showed that the intercalation of sodium dodecyl sulfonate into the lanthanum organic MMT resulted in its excellent thermal stability. The use of the La‐OMMT samples in polyvinyl chloride (PVC) resins was tested, and the TG/DTG results revealed that the three La‐OMMTs could significantly enhance the thermal stability of PVC. The modified La‐OMMT with the highest thermal stability is expected to be useful in polymer/layered silicate nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41535.

Effect of filler surface functionalization on the performance of Nafion/Titanium oxide composite membranes

The phenylsulfonic functionalized nanometric titania (TiO2-PhSO3H) was synthesized to be used as filler in Nafion-based composite membranes for direct methanol fuel cell (DMFC) applications. The organic moieties were covalently bound on the surface of TiO2 nanoparticles and the hybrid product was characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric and differential thermal analysis (TG/DTA), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) analysis. TiO2-PhSO3H showed higher ion exchange capacity (IEC) and proton conductivity values with respect to those of TiO2. The incorporation of TiO2-PhSO3H in Nafion led to a mechanical reinforcement of the membranes and higher conductivity than that obtained with unfilled Nafion. The composite membrane containing 10wt.% of TiO2-PhSO3H showed an increased crystallinity and the highest conductivity, reaching 0.11Scm−1 at 140°C. DMFC tests were carried out showing that the use of the organic-inorganic hybrid filler leads to a general improvement in the cell performance, in terms of higher current and power density and reduced methanol crossover.

Morphology Design of IRMOF-3 Crystal by Coordination Modulation

A one-pot synthesis design on shape-controlled growth of Zn-based isoreticular metal–organic framework (i.e., IRMOF-3) was carried out in this work with the controllable crystal morphological evolution from simple cubes to several complex shapes. A new synthetic protocol was devised where poly(vinylpyrrolidone) (PVP), noble metal source (AgNO3), mixed solvents (N,N-dimethylformamide (DMF)–ethanol mixture) and tetramethylammonium bromide (TMAB) were mutually introduced to the reaction medium as surfactant, adjuvant, accelerator, and structure-directing agent (SDA), respectively. Meanwhile, the crystallization process was investigated by a series of time-dependent experiments. Indeed, the added modulators and crystallization time were able to regulate the growth and thus the morphology of the final products. The resulting homogeneous IRMOF-3-Ag-n materials with unique and novel crystal morphologies were characterized via scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric and differential thermal analyses (TG-DTA), transmission electron microscopy (TEM), infrared spectrum (IR), and optical microscope characterizations. Various shapes of IRMOF-3-Ag-n crystals as sorbents for capturing dibenzothiophene (DBT) were evaluated. Among all the morphology-controlled samples, IRMOF-3-Ag-5 with hollow sphere morphology was demonstrated to show the highest DBT capture capacity due to its unique morphology.

The Effect of Surfactants and Co-Reagents on the Microstructure, Morphology and Optical Properties of ZnO Nanoparticles Synthesized by Microwave Irradiation

Zinc oxide nanoparticles (ZnO NPs) have been synthesized through microwave irradiation by using different surfactants (Polyvinyl pyrrolidone (PVP), Polyethylene glycol (PEG) and Sodium dodecyl benzene sulphonate SDBS)) and co-reagents (NH3 and NaOH). The synthesized samples were analyzed by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning and transmission electron microscopy (SEM and TEM). Depending on the surfactants and reagents used, various ZnO nanostructures having spherical, rectangle, star-like, needle and rod-like structures with different crystallite size have been obtained. The optical and photoluminescence properties of the samples were investigated and discussed in terms of the different surfactant and reagents used for the synthesis. Keywords: Microwave synthesis, PEG, ZnO, PVP, SDBS, surfactants.

Preparation of Anatase Hollow TiO2 Spheres and Their Photocatalytic Activity in the Photodegradation of Chlorpyrifos

AbstractHollow anatase titania (TiO2) spheres were synthesized using fructose and tetrabutyl titanate (Ti(OC4H9)4, TBT) as the precursors via the conventional hard template method. The morphological, structural and thermal properties of the products were characterized using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG‐DTA), BrunauerEmmettTeller (BET) surface area analysis and diffuse reflectance ultraviolet visible (DR UVVis) spectroscopy. XRD revealed that the hollow TiO2 prepared was in the anatase phase and the BET surface area measured was about 22 m2 g−1. The photocatalytic activity of the synthesized hollow anatase TiO2 in the photodecomposition of chlorpyrifos was 18.67 % higher than that obtained using commercial TiO2.

Effect of cesium chloride addition on crystal growth, structural, thermal and optical properties of γ‐glycine single crystal

Single crystals of γ‐glycine in the presence of cesium chloride were grown from aqueous solution by low temperature solution growth technique. The phase purity and crystal structure of the grown crystals were confirmed by Powder X‐ray diffraction analysis. The presence of functional groups were confirmed by FT‐IR spectrum. Thermal analysis of the grown crystal was determined by thermogravimetric and differential thermal analysis (TG/DTA), which results the thermal stability of the grown crystal. The optical absorption and lower cut‐off values were ascertained by recorded UV‐Visible spectrum of γ‐glycine crystals. The existence of second harmonic generation efficiency of frequency doubling was found to be 6 times greater than that of KDP.

Synthesis, characterization, DC-electrical conductivity and γ-ray effect on Ag1+, Y3+ double doped nano lithium manganates (LiMn2−2x AgxYxO4) for rechargeable batteries

Abstract Pristine lithium manganate (LiMn2O4) and Ag1+, Y3+ double doped nano lithium manganate [LiMn2−2x AgxYxO4, (x = 0.025, 0.05)] spinels were synthesized via a coprecipitation method for rechargeable batteries applications. The synthesized LiMn1.9Ag0.05Y0.05O4 was exposed to different doses of γ-irradiation (10 and 30 kGy). The resulting spinel products were characterized by using thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), electronic (UV-Vis) and electron spin resonance (ESR) spectra. LiMn2O4 exhibited a discharge capacity of 124 mAhg−1 while LiMn1.9Ag0.05Y0.05O4 had discharge capacities of 129 and 137 mAhg−1 for non irradiated and γ-irradiated (30 kGy) samples, respectively. The effects of the dopant cations and γ-irradiation on the discharge capacity and DC-electrical conductivity of some synthesized spinels were studied.