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In this paper, a novel hydrogen-bonded liquid crystalline binary complex system was synthesized from pure mesogenic 4-(octyloxy)benzoic acid (8OBA) and non-mesogenic n-aminobenzoic acid (nABA, n = 3, 4) chemicals. Differential scanning calorimeter (DSC) experiments were performed to investigate the thermal properties of the synthesized samples, and polarized optical microscopy (POM) experiments were performed to investigate the mesogenic phase textures. The DSC and POM results showed that the phase sequence was Cr ↔ SmA ↔ SmC ↔ N ↔ I during continuous heating and cooling cycle. In addition, the thermal stability factor, phase transition entropy, and phase transition activation energy were calculated using DSC data. According to the calculated values, it was concluded that the mesogenic phases of the synthesized complexes occur regularly and the most stable phase is the SmC phase. Moreover, the optical tilt angle value for the SmC phase was measured and it was seen that the value increased up to 29° and 30° for 8OBA/4ABA and 8OBA/3ABA complexes, respectively. The formation of hydrogen bonds between the mesogenic and non-mesogenic molecules in the synthesized mesogenic structure was confirmed by Fourier-transformed infrared spectroscopy (FTIR). Furthermore, XRD results showed that the molecular ordering of the synthesized hydrogen-bonded 8OBA/4ABA and 8OBA/3ABA binary complexes occur in a monoclinic structure in the solid phase. [ABSTRACT FROM AUTHOR]

Bi doped 2CaO-Al2O3-SiO2 (gehlenite) glasses were prepared by conventional melting. The concentration of Bi3+ was 0, 0.25, 0.50 and 1.50 mol. %. The prepared samples were X-ray amorphous except of the undoped sample and the sample with the highest content of Bi3+, for which XRD records revealed traces of crystalline gehlenite. Differential thermal analysis (DTA) was used to study the thermal properties of prepared glasses, performed in the atmosphere of nitrogen at 5 different heating rates. The DTA records of all studied samples contained only one exothermic effect. Based on the results of XRD analysis, the exothermic effect was attributed to the crystallization of gehlenite. The XRD patterns of all samples measured after DTA analysis contained gehlenite as the main crystalline phase (01–074-164 COD). The DTA records measured at a heating rate of 10 °C.min−1 revealed a significant decrease in the temperatures of maxima of the exothermic peaks (from 982 °C to 943 °C) with the increasing Bi doping. The model approach using the Johnson–Mehl–Avrami-Kolgomorov (JMAK) equations with six different values (1.5, 2, 2.5, 3, 3.5 and 4) of Avrami parameters (m) was used to study crystallization kinetics of gehlenite glasses. The model that best describes the experimental data was found, using the AIC (Akaike criterium) and wAIC (Akaike weight) criteria: A (frequency factor) and Eapp (apparent activation energy) were determined. Based on kinetic parameters values, it is concluded that the nucleation rate is constant. Irrespective of the Bi content, the movement of the growth zone is controlled by diffusion and 3D growth is characteristic for the gehlenite crystals growth. [ABSTRACT FROM AUTHOR]

The polymorphism of tolbutamide and chlorpropamide under melting/crystallization was investigated with using DSC and in situ X-ray powder diffraction. The asymmetry in thermal transformations was revealed for both substances. Under heating, all tolbutamide/chlorpropamide polymorphs transform into high-temperature IH/ε polymorph, which melts at 128 °C. The crystal structures of the high-temperature polymorphs, IH and ε, are very similar to each other in the unit cell parameters and in the arrangement of z-shaped infinite hydrogen-bonded ribbons. Under cooling, other polymorph crystallizes from the melt, V for tolbutamide and β for chlorpropamide, thus making easy the obtaining of these metastable polymorphs. The polymorphs of tolbutamide and chlorpropamide crystallized from their melts turned out to be also very similar to each other in their structures (space group, unit cell parameters, arrangement of π-shaped infinite hydrogen-bonded ribbons). Solid–solid transformation V ⇒ II in tolbutamide was detected both in samples stored under room conditions and those melted in capillaries, thus providing new easy way for II tolbutamide crystallization. In generalizing our results, one can expect that if evident similarity is found among the polymorphs of similar molecules in their crystal structure, the similarity in their thermal properties can be also found, and vice versa. [ABSTRACT FROM AUTHOR]

Poly(ether ether ketone) (PEEK) is a high-performance thermoplastics with outstanding mechanical properties and thermal resistance (serving temperature up to 250 °C). Although many studies have been performed on the stress–strain behavior and related modeling, less attention has been paid on the structural and orientational evolution of PEEK during tensile deformation. In this work, the orientational and structural evolution during tensile deformation at a wide range of temperatures from 30 to 170 °C was probed ex situ by wide-angle X-ray diffraction and differential scanning calorimetry. The enthalpy of cold crystallization of PEEK as a function of strain, which reflects the content of amorphous fraction and the disorder degree of crystals, presents an interesting dependence on tensile temperature. The evolution of orientation with strain is strongly dependent on the tensile temperature. Oriented PEEK presents much improved modulus and tensile strength compared to that of undrawn PEEK. This finding demonstrated that pre-stretching especially at temperatures above Tg is an effective way to improve the mechanical property of PEEK. [ABSTRACT FROM AUTHOR]

Two trivalent rare earth compounds [Ln(3-MOBA)3(terpy)(H2O)]2 (Ln = Tb (1), Eu (2); 3-MOBA = 3-methoxybenzoate, terpy = 2,2′:6′,2″-terpyridine) were obtained in solid state, and the structure of 1 was determined by X-ray diffraction. The analysis of characterization was performed by elemental analysis, IR spectra, X-ray powder diffraction, thermogravimetric and differential scanning calorimetry coupled to infrared spectrometer (TG/DSC-FTIR). Besides that the luminescent properties and antibacterial activities were discussed. The crystal structure of 1 revealed that the asymmetric units were further stitched together to form 1D chain along the x-axis direction through the offset face-to-face π···π weak stacking interactions. Luminescence investigation revealed that compounds exhibited strong green and red emissions and the fluorescence quantum yield of two compounds were measured. What's more, the Commission Internationale de L'Eclairage chromaticity diagrams were presented. The antibacterial activity studies show that two compounds had good antibacterial actions on E. coli, S. aureus and no antibacterial activities on C. albicans. [ABSTRACT FROM AUTHOR]

Three novel ternary lanthanide complexes [Ln(2,5-DClBA)3(terpy)(H2O)] (Ln = Eu (1), Tb (2), Ho (3), 2,5-DClBA = 2,5-dichlorobenzoate, terpy = 2,2:6′,2″-terpyridine) have been successfully synthesized and characterized by single-crystal and powder X-ray diffraction. Complexes 1–3 are isostructural, and each metal center is nine-coordinated with distorted monocapped square antiprismatic coordination geometry. The mononuclear units are assembled into 1D, 2D, 3D supramolecular structures by the π–π stacking and halogen–halogen interactions. Thermal decomposition mechanisms of the title complexes were investigated by thermogravimetric analysis and further authenticated by TG/DSC-FTIR techniques. The solid-state fluorescent properties of complexes 1–2 were studied at room temperature, and characteristic emission was observed for all complexes. Complex 1 exhibits the strong red emission, while the complex 2 is green under UV light. Moreover, the antibacterial activities of the complexes against Candida albicans, Escherichia coli and Staphylococcus aureus were also evaluated. [ABSTRACT FROM AUTHOR]

Phase relationships in the Tb-Al-Si system have been established and experimentally studied at 500 °C. The main experimental techniques used were scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. Some samples have been analyzed by differential thermal analysis. Six ternary compounds form in the system: the five ternary structures τ-TbAlSi, τ-TbAlSi, τ-TbAlSi, τ-TbAlSi and τ-TbAlSi have been confirmed, while the compound τ (TbAlSi, crystal structure oI10-WCoB) was not previously known in the literature for the Tb-Al-Si system, but its formation was known in other R-Al-Si (R: Dy,Ho,Er,Tm) systems. The two ternary phases τ-TbAlSi and τ-TbAlSi show a homogeneity range, at constant Tb content. A number of boundary binary phases dissolve the third element, at 500 °C, forming ternary solid solutions extending into the ternary field: Tb(AlSi) (0 ≤ x ≤ 0.13), Tb(AlSi) (0 ≤ x ≤ 0.02), Tb(AlSi) (0 ≤ x ≤ 0.08), Tb(AlSi) (0 ≤ x ≤ 0.10), Tb(AlSi) (0 ≤ x ≤ 0.10), Tb(AlSi) (0 ≤ x ≤ 0.24) and Tb(AlSi) (0 ≤ x ≤ 0.15). The Al and Si richest part of the system is characterized by the coexistence of three phases (Al), (Si) and TbAlSi (τ); this behavior is common to all the known R-Al-Si phase diagrams. The phases are involved in the ternary eutectic equilibrium L ⇄ (Al) + (Si) + TbAlSi close to the binary eutectic point of the Al-Si binary system. Experimental measurements confirm the ternary eutectic reaction at a temperature of 565 °C. [ABSTRACT FROM AUTHOR]

The characterization of three commercial powders of niobium(V) oxide received from two producers was made. The thermal behavior of NbO up to melting point and its microstructure were studied using X-ray powder diffraction, thermoanalytical methods (DSC/TG), infrared spectroscopy (IR) and scanning microscopy. Analysis of the obtained results revealed that the starting structure of niobium(V) oxide and its thermal behavior depend on the origin of niobia. Depending on the origin of the powder and of its thermal treatment, three polymorphs of NbO can be observed. Sintering of powders above 1200 °C results in the formation of single phase, H-NbO. [ABSTRACT FROM AUTHOR]

Three crystal forms of iopamidol, an iodinated contrast media used in radiology, have been so far elucidated: an anhydrous, a monohydrate and a pentahydrate form (labeled hereafter as W0, W1 and W5, respectively), which showed the occurrence of different conformations, atropisomeric in nature. Specifically, the anhydrous and monohydrate forms contain iopamidol with a ' syn' conformation of the two symmetric sidearms, while an ' anti' conformation was found in the pentahydrate, making it a conformational (pseudo)-polymorph of the first two. The three crystal forms have been here investigated by means of DSC, variable temperature X-ray powder diffraction and Raman spectroscopy. This study enabled us to highlight the thermal-induced transformations, leading to the discovery of new crystal forms, for a total of four hydrated and four distinct anhydrous phases. In particular, the DSC curve of W0 revealed only a reversible solid-solid transition at around 180 °C before melting, with subsequent degradation above 300 °C. W1, after the loss of lattice water around 100 °C, shows a characteristic split peak at about 250 °C, which is attributed to melting. Below 150 °C, powder diffraction of W1 suffers of minor changes, with a smooth variation of the lattice parameters, in agreement with a progressive loss of water in a reversible event, monitored also by DSC. At variance, W5 evidenced an irreversible loss of water in three distinct steps, for three, one and one HO molecules each, respectively; subsequent transitions occur at 140 and 180 °C, before melting at 240 °C. Three clearly visible transformations were also detected by variable temperature powder diffraction measurements, where the loss of three molecules of water in a single step, generating a bis-hydrated species (W2), is followed by a second dehydration process leading, above 75 °C, to a new monohydrate phase W1′, different from the known W1 form. The Raman spectra of the three crystal forms, measured upon heating up to 160 °C, evidenced changes in spectral regions of amides that, according to our simulations of the vibrational properties, can be attributed to changes of the hydration properties and, more significantly, in terms of the ' syn' and ' anti' conformations. [ABSTRACT FROM AUTHOR]

Nanocomposites based on poly(3-hydroxybutyrate) (P3HB) and Cloisite30B were prepared by direct mixing in a co-rotating twin-screw micro-extruder. The X-ray diffraction method and transmission electron microscopy allowed to identify the nanostructure. Thermal properties of the obtained nanocomposites were investigated with the use of thermogravimetry (TG) and differential scanning calorimetry (DSC). TG analysis of nanocomposites showed that thermal stability of the obtained nanocomposites was higher by approximately 20 °C than the neat P3HB. The phase transitions such as the glass transition, the crystallization and the melting have been studied by the DSC. The influence of nanofiller's presence in the polymer matrix on glass transition, crystallization and melting processes of the material obtained was determined and compared with the neat P3HB. The clay addition to the polymer matrix made the increase of the degree of crystallinity and the increase of the degree of amorphous of semi-crystalline P3HB. Furthermore, mechanical properties such as impact strength, flexural strength and hardness were investigated and compared with unfilled P3HB. Obtained nanocomposites containing 1 mass/% of Cloisite30B have the best mechanical properties, better than the neat P3HB. [ABSTRACT FROM AUTHOR]

Nanofluids of LiCO-NaCO-KCO improved by three nano-AlO samples are firstly prepared by means of two-step aqueous method to enhance thermal properties for high-temperature heat transfer, when used as heat transfer fluids and thermal energy systems for concentrating solar power systems. Specific heat of ternary carbonates containing AlO of 0.2, 0.4, 0.8, 1.0, 1.4 and 2.0 mass% is measured, and nanofluids with 1.0 mass% of 20-nm AlO, 1.0 mass% of 50-nm AlO and 0.8 mass% of 80-nm AlO are selected as superior candidates. The maximum enhancement of specific heat is 18.5% in solid and 33.0% in liquid, 17.9% in solid and 22.7% in liquid, 13.2% in solid and 17.5% in liquid for nanofluids containing 20-, 50- and 80-nm AlO. Thermal conductivity is, respectively, improved by 23.3, 28.5 and 30.9% under the addition of AlO. New chemical bonds and crystals are scarcely formed in composites through FT-IR and XRD determination. SEM images certify that nano-AlO are homogeneously mixed into nanofluids and this structure may be a critical incentive for enhancing thermal properties. There are no significant changes with respect to the heat flow, melting/freezing point and latent heat after the 30 circles of determination. Briefly, it can be speculated that these nanofluids will exhibit tremendous potential in the coming applications of heat transfer and thermal storage for concentrating solar power systems. [ABSTRACT FROM AUTHOR]

Thermal properties of raw aluminosilicate ceramic glazes in the multicomponent system of SiO-AlO-CaO-KO-NaO-ZnO modified by ZnO addition were studied by differential thermal analysis (DTA), dilatometry (DIL), hot-stage microscopy (HSM), X-ray diffraction and fourier transform infrared spectroscopy (FTIR). Using the method of differential thermal analysis, the ways in which zinc oxides affect the temperature of transition ( T ), crystallisation ( T ) were determined. An analysis of the DTA data obtained during thermal tests showed that an increase in ZnO content results in decreasing the T value. Also, the influence of ZnO on characteristic temperatures and viscosity of glazes was checked. The introduction of zinc oxide (ZnO) into the glaze composition contributes to the decrease in viscosity of such glazes. An increasing ZnO content in the glazes also causes the reduction in softening ( T ), half-sphere ( T ) and fusion ( T ) temperatures. The mid-infrared spectroscopy showed that the thermal properties of glazes in SiO-AlO-CaO-KO-NaO-ZnO system modified by addition of ZnO can be associated with the depolymerising influence of zinc ions on the structure of the tested glazes. [ABSTRACT FROM AUTHOR]

A glass with the composition of the SiO-NaO-CaO-PO was synthesized by sol-gel method at temperature of 900 °C, and then yttrium-, silver- and cerium-containing glasses were prepared at the same conditions using this base system. The structural and thermal properties of the glass samples were investigated by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray (EDX) spectroscopy and differential thermal analysis techniques. The Ca(PO)(SiO) phase having the orthorhombic crystal system is detected for each sample without any secondary phase, and this phase is confirmed by the FTIR spectra. With the addition of Y, Ag and Ce to the SiO-NaO-CaO-PO system, the variations in the average crystallite size, crystallinity percent, lattice parameters and unit cell volume are observed. A decrease in the crystallization peak temperature and the changes in the glass transition temperature are seen with the addition of Y, Ag and Ce to the base system. The addition of Y, Ag and Ce to the base glass increases significantly its density. The EDX spectra of the as-prepared samples verify the introduction of the as-mentioned elements. [ABSTRACT FROM AUTHOR]

The aim of the present work was to investigate the crystallization kinetic of spodumene-/cordierite-based glass-ceramics. Thus, three glasses were prepared with compositions based predominantly on cordierite and β-spodumene crystalline phases, and a mass ratio 1:1 of both phases. The kinetic parameters were determined by means of non-isothermal methods using differential thermal analysis. A multi-peaks fit method was used based on the Fraser-Suzuki equation to determine the crystallization temperature peak. The crystallization kinetic was investigated using the Ozawa and Kissinger methods. The samples were crystalized according to DTA analyses and characterized by using X-ray diffraction. Additionally, the coefficient of thermal expansion and electrical properties of the glass-ceramics was determined. The results showed activation energy for crystallization ranging from 121 to 333 kJ mol. The main crystalline phases were β-spodumene to composition L, cordierite and β-quartz to composition C and β-quartz and spinel to composition CL. Taking into account the thermal and electrical properties of the heat-treated samples, these glass-ceramics show potential to LTCC (low thermal co-fired ceramics) application. [ABSTRACT FROM AUTHOR]

The new energetic compound 1 H-pyrazole-1-carboxamidine dinitramide (PACADN) was synthesized by the reaction of silver dinitramide with 1 H-pyrazole-1-carboxamidine hydrochloride. Its structure was confirmed by single-crystal X-ray diffraction, elemental analysis and Fourier transform infrared, ultraviolet-visible and nuclear magnetic resonance spectroscopy analyses. PACADN crystallizes in the orthorhombic space group Pnna. The thermal decomposition was studied with differential scanning calorimetry, thermogravimetry analysis and thermogravimetric tandem infrared spectrum. The results indicated that PACADN exhibits good resistance to thermal decomposition up to 433 K and has 90.24 % mass loss between 433 and 523 K by undergoing exothermic decomposition. The kinetic parameters of the thermal decomposition of PACADN were also obtained from the derivative thermogravimetry analysis data using Kissinger's method, with E = 143.2 kJ mol. Moreover, the detonation velocity and detonation pressure of PACADN were calculated as 7.2 km s and 21 GPa by applying the Kamlet-Jacobs (as follows). [ABSTRACT FROM AUTHOR]

The thermal reaction properties of the aluminum nanoparticles/copper (II) oxide nanoparticles/poly(vinylidene fluoride) (Al-NPs/CuO-NPs/PVDF) nanocomposite (mass ratio of Al-NPs/CuO-NPs/PVDF = 20/60/20) were investigated by means of thermogravimetry-differential scanning calorimetry-mass spectrometry (TG/DSC-MS) and X-ray diffraction (XRD) analysis. Al-NPs/PVDF (mass ratio of Al-NPs/PVDF = 50/50) and CuO-NPs/PVDF (mass ratio of CuO-NPs/PVDF = 75/25) nanocomposites were also prepared as a comparison. It is observed that PVDF in the Al-NPs/PVDF nanocomposite acts as an oxidizer. The fluorine ions/fluorinated gases formed at elevated temperatures react with the AlO shell leading to the formation of aluminum fluoride (AlF). The oxide shell is degraded from the reaction between fluoride ions and AlO, leaving the core Al available for reaction with fluorine ions/fluorinated gases. H ( m/z = 2), OH ( m/z = 17), HO ( m/z = 18), HF ( m/z = 20), CF ( m/z = 31) and CHF ( m/z = 33) fragments were detected in the gaseous products. For CuO-NPs/PVDF nanocomposite, oxygen was released due to the decomposition of CuO to CuO and then Cu metal, oxidizing hydrocarbon groups in PVDF. Species of OH ( m/z = 17), HO ( m/z = 18), CO ( m/z = 44), CHF ( m/z = 45) and HF ( m/z = 20) were detected in the gaseous products. The final reduction product of CuO is Cu metal. It is observed that PVDF in the Al-NPs/CuO-NPs/PVDF nanocomposite acts as both oxidizer and reducer in the thermal decomposition. Below 550 °C, PVDF is oxidized by CuO-NPs and oxidizing Al-NPs at the same time, resulting mass reduction. After 550 °C, the remaining Al-NPs and copper (I)/copper (II) oxide will proceed the exothermic solid-state thermite reaction. OH ( m/z = 17), HO ( m/z = 18), CO ( m/z = 44), CHF ( m/z = 45) and HF ( m/z = 20) were the main products of the decomposition of Al-NPs/CuO-NPs/PVDF nanocomposite. [ABSTRACT FROM AUTHOR]

Strontium chloroapatite (SrApCl) and its borosilicate glass (BSG)-bonded composites loaded with simulated pyrochemical chloride waste (w) compositions were prepared by solid-state reaction route. The products were characterized by powder XRD. Enthalpy increments of the composites were measured by drop calorimetric method at the temperature range of 373-773 K using a homebuilt calorimeter. Heat capacity ( C), entropy ( S) and Gibbs energy functions ( G) in the temperature range of 298-773 K of the above-synthesized composites have been evaluated from the enthalpy increments data by using least-squares fitting. C values found to be in the range of 0.596-0.751, 0.530-0.724, 0.570-0.938, 0.598-0.981 and 0.850-1.097 J K g for SrApCl, SrApCl-10w, SrApCl-20BSG, SrApCl-10w20BSG and BSG, respectively, at the temperatures ranging from 298 to 773 K. [ABSTRACT FROM AUTHOR]

This study deals with the effects of Ru-Bi partial substitutions on the thermal, structural and mechanical properties of BiRuPbSrCaCuO ( x = 0.0, 0.025, 0.050, 0.075) system, produced by using glass ceramics method. The effects of Ru-Bi partial substitutions on glass transition, nucleation and crystallization temperature were analyzed via differential thermal analyzer (DTA). Besides, microstructure and micromechanical properties of Ru-Bi partially substituted BSCCO glass ceramics were also investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Vickers microhardness measurements. From the DTA results, nucleation kinetics were studied by using Ozawa, Augis-Bennett, Takhor and Kissinger equations. In addition to this, activation energies and Avrami parameters were also calculated. According to the results of the thermogravimetric analyses, the amount of oxidation was seen to be increased with increasing Ru concentration. Moreover, the lattice parameters, volume fractions and surface morphologies of our newly produced glass ceramics were investigated by XRD and SEM measurements, respectively. RISE behavior obtained from the microhardness measurements for all samples. Microhardness, elastic modulus, yield strength and fracture toughness values decreased with increasing Ru doping. [ABSTRACT FROM AUTHOR]

Stearic acid/diatomite composite form-stable phase change materials (PCMs) have been prepared by using a direct impregnation method without vacuum treatment. The surface morphology, chemical compatibility, thermal properties and thermal stability were characterized by scanning electron microscopy, Fourier transform infrared spectrometer and X-ray diffraction (XRD), differential scanning calorimeter and thermogravimetric analysis (TG), respectively. The results show that there are only physical interactions between stearic acid and diatomite in composite PCM. XRD analysis reveals that crystal type is not affected by composite technology of SA/diatomite composite form-stable PCM with decrease in crystal size due to the limited pores in diatomite. The melting and freezing temperatures of stearic acid/diatomite composite, respectively, are 52.3 and 48.4 °C. The latent heat of SA/diatomite composite reaches 57.1 J g, potential to be used in a practical application. TG result indicates that the decomposition of SA/diatomite composite starts at 192 °C, implying that the SA/diatomite has a good thermal stability. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of methane (CH) on zeolite from Sivas-Yavu region of Turkey and on forms treated with 1 M heavy metal nitrate solutions (AgYZ, Cu YZ and FeYZ) and 1, 3 and 5 M HCl solutions (HYZ, 3HYZ and 5HYZ) was investigated. Adsorption isotherms of methane by zeolite minerals were obtained using volumetric apparatus at 0 and 25 °C up to 100 kPa. Natural and modified samples were characterized by X-ray fluorescence, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis and nitrogen adsorption methods. Quantitative XRD analysis showed that the major components of the natural zeolite were clinoptilolite and mordenite, together with minor amounts of quartz, feldspar and clay mineral. Among all the modified forms, Fe-form of zeolite sample exhibited the highest adsorption capacity for CH at both temperatures. The adsorption capacity of CH on FeYZ increased from 0.597 to 0.796 mmol g as the temperature decreased from 25 to 0 °C. In addition, uptake of CH on the adsorbents decreased with increasing acid concentrations. [ABSTRACT FROM AUTHOR]

In this work, a combined method of using DSC, TG and XRD analysis in order to determine an amount of decomposed α-CSH in its tribochemically activated mixture with quartz is presented. Furthermore, the influence of the grinding on the phase transition and heat flow during the hydration of this mixture is determined. The results showed that the product in which α-CSH prevails is obtained after 12 h of the hydrothermal synthesis at 200 °C in stirred (50 rpm) suspensions. The purification of mentioned product using distilled water (water/solid = 500) for 5 min is enough to eliminate remaining Ca(OH). The stability of α-CSH during the purification was confirmed using DSC and XRD analysis. A strong correlation between heat absorption values of the α-CSH decomposition at 470 °C and its quantity in the mixture with quartz was noticed ( R = 0.9929). According to the plotted calibration curve, the amount of decomposed α-CSH during the tribochemical activation was determined: within the first minute, it reaches 32.28 % and gradually increases to 48.73 % after 20 min. During the decomposition of α-CSH, the semi-crystalline calcium silicate hydrates form, which recrystallize to wollastonite at 850 °C; meanwhile, the remaining α-CSH transforms to larnite. The complex tribochemical and thermal activation of α-CSH-quartz mixture leads to a vivid increment of its hydraulic activity: the heat flow of the main hydration reaction and the total heat values reached 3.1 mW g and 104.48 J g, respectively. [ABSTRACT FROM AUTHOR]

Structural elucidations of upper rim functionalized tetramethoxy resorcin[4] were achieved with FT-IR and H-C-NMR spectroscopy. Further analysis was performed with both powder and single crystal X-ray diffraction. A thermal degradation of the three tetramethoxy resorcin[4]arenes was carried out by means of thermo gravimetry, and differential scanning calorimetry revealing that the nature of the derivatives 'group' (aromatic or aliphatic) has a profound effect on their thermal properties. These compounds have excellent thermal stability. [ABSTRACT FROM AUTHOR]

Ammonium dihydrogen phosphate (ADP) crystals have been grown in the presence of various concentrations (1, 5 and 10 mol%) of cadmium(II) salt by slow evaporation of saturated solution method. The concentration of the incorporated Cd ion has been determined by energy-dispersive X-ray spectrometry. The surface nature of the as-grown crystals has been analysed by scanning electron microscopic studies. Presence of Cd in the crystal lattice of ADP has not altered the basic structure of ADP as evidenced by powder X-ray diffraction and single-crystal X-ray diffraction analyses. Thermogravimetry and differential thermal analyses of the samples reveal that there is no physically adsorbed water molecule in the pure and doped specimens. The grown crystals were also characterized by FT-IR, UV-Vis and diffuse reflectance spectra. It is interesting to observe the second harmonic generation efficiency, a nonlinear optical property estimated by Kurtz powder technique has been increased when compared to the pure ADP up to the moderate concentration of cadmium. [ABSTRACT FROM AUTHOR]

Nanocrystalline nickel ferrite and copper nickel ferrite materials were synthesized through surfactant Tween 80-assisted hydrothermal reaction at low temperature using metallic copper, nickel, and iron as raw materials. Thermogravimetric (TG) and differential thermal analysis (DTA) were used to determine the decomposition of the precursors. Phase composition, microstructural characterization, and distribution of cations in tetrahedral and octahedral sites of crystal structure properties of synthesized ferrite materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) absorption, and Mössbauer spectroscopy. The impedance spectroscopic studies of copper nickel ferrite sintered ceramics were carried out at room temperature. TG and DTA of precursors revealed that the crystallization temperature for spinel ferrites phases formation was around 650 °C which were being synthesized through Tween 80-assisted hydrothermal process in highly basic reaction at 180-200 °C for 11-13 h in PTFE-lined stainless steel autoclave. XRD analysis and Rietveld refinement study confirm the formation of single-phase cubic spinel nickel ferrite (NiFeO) and copper nickel ferrite (NiCuFeO) with cell parameters 8.3385, 8.3595 Å and space group Fd3 m, respectively. The synthesized ferrite products showed extensive XRD line broadening, and the average crystallite sizes of NiFeO and CuNiFeO ferrites were in range of 21-29 nm and 18-23 nm, respectively. Mössbauer parameters are characteristic of substituted Cu-Ni-FeO ferrite material. Isothermal shrinkage characteristic and coefficient of thermal expansion were determined by dilatometry. The ferrite specimens showed excellent densification at 1,050 °C temperature, and uniformly fine grain-sintered ceramics with submicron grain size (10-18 μm) were obtained after sintering at 850 and 1,050 °C. Sintering at 1,050 °C, results in the formation of depletion layer at grain boundaries which act as trapping centers for the carriers and an increase in the impedance values are conferred. [ABSTRACT FROM AUTHOR]

The amorphous SbSe film with a thickness ~0.9 µm was prepared by thermal evaporation and its composition was confirmed using an energy-dispersive X-ray analysis. The amorphous state was checked by an X-ray diffraction analysis. The optical gap E was determined to be 1.32 eV. The glass transition temperature could not be found by either a differential scanning calorimetry or a thermomechanical analysis. The film was crystallized and characterized using the quasi-isothermal method. The temperature dependence of the isobaric heat capacity was raised monotonously and no drop over the course of the crystallization was observed. The temperature-modulated thermomechanical analysis determined a temperature T = 133 °C which can be assumed to be the temperature of the structural reorganization beginning. Raman spectra of amorphous SbSe revealed that the vibrations of both the amorphous and crystalline phase are close to one other. Raman scattering revealed that both the short and the medium-range order of amorphous and crystalline phases are similar. [ABSTRACT FROM AUTHOR]

Mono-phase high critical temperature (Bi,Pb)-2223 superconductor from the off-stoichiometric BiPbSrCaCuO belonging to the tetragonal system, has been obtained. We studied the crystalline structure, the stress of second order, and the texture of the surface pellet, in the framework of XRD diffractometry. Results of the thermal measurements made in the nitrogen, with a heating rate of 10 K min, from room temperature (RT) to 1273.15 K, show a slow mass decrease of 1.25 % from RT to 1003.15 K probably due to the elimination of water, oxygen, and of the other gases accumulated on the crystallite surface through chemical adsorption. Two endothermic processes were evidenced on DSC, and DTG curves: the first in the range of 1135.15-1193.15 K (melting and slow decomposition), and another after 1217.45 K (decomposition). The contribution of crystal lattice to the estimated specific heat capacity was in conformity with the Einstein model, giving for the Einstein temperature a value of 1297.5 K. In conformity with the Müller critical state model, we found linear dependences for intragrain critical transition temperature, T, and intergrain coupling temperature, T, versus the amplitude of the external AC magnetic fields. There was evidenced that intergrain critical currents are five orders smaller than the intragrain critical currents. [ABSTRACT FROM AUTHOR]

Nanometric carbides of transition metals and silicon are obtained by using precursors. Control of the course of these processes require data concerning transformations of single precursor, transformations of precursor in the presence of reducing agent and synthesis of the carbide. In this work, the way of investigating such processes is described on the example of thermal decomposition of (NH)MoO·4HO (precursor) in argon. The measurements were carried out by TG-DSC method. The solid products were identified by XRD method, and the gaseous products were determined by mass spectrometry method. There was demonstrated that the investigated process proceeded in five stages. Kinetic models (forms of f( α) and g( α) function) most consistent with experimental data and coefficients of Arrhenius equation A and E were determined for the stages. The Kissinger method and the Coats-Redfern equation were applied. In case of the Coats-Redfern equation, the calculations were performed by analogue method. In this way good consistency between the calculated and determined conversion degrees α( T) at practically constant values of A and E were obtained for distinguished stages and different sample heating rates. [ABSTRACT FROM AUTHOR]

Nanocrystalline magnesium chromite spinel was synthesized through hydrothermal reaction of metal nitrate solutions in stoichiometric amount at different pH, temperature and time intervals. The synthesized products were characterized for crystallinity, phase identification, and surface morphology by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD patterns showed that as-synthesized product remained amorphous up to 250 °C. However, well-crystallized magnesium chromite spinel structure is formed after calcination at 850 °C. Rietveld refinement study confirms the formation of single-phase cubic structure MgCrO with lattice parameter a = 8.3347 Å, and Fd3 m space group. The as-processed MgCrO products showed extensive XRD line broadening, and the mean crystallite size of such crystals was found to be mainly in size range of 85-124 nm. Surface SEM images of calcined specimens revealed that the matrix is uniform, and no separation of secondary phase was detected. Thermal stability was examined by thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry. TG/DTA reveals that MgCrO is thermally stable above 700 °C. Fourier transform infrared (FTIR) spectra studies shows two strong bands, one around 600 cm which is attributed to the intrinsic vibrations of tetrahedral and other at 400 cm is due to octahedral one. FTIR confirms the formation of metal oxides. The bandgap energy was estimated by absorption spectroscopy in ultraviolet-visible range and was found to be 0.693 eV for MgCrO specimen sintered at 1,000 °C. Isothermal shrinkage characteristic and coefficient of thermal expansion were determined by dilatometry. The powder specimens showed excellent densification at 1,250 °C temperature and uniformly fine grain sintered ceramics (>90 % relative density) with submicron grain size (2-5 μm) were obtained after sintering at 1,000-1,250 °C. Impedance studies were carried out at room temperature and equivalent circuit model ( R Q) ( R Q) ( R Q) is used to explain different relaxation processes. We report largest impedance values i.e., 6.74 × 10 Ω, reduced dielectric constant (≈1.0), and low tangent loss (0.8) for MgCrO sintered at 1,250 °C. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) and CaCuTiO (CCTO) composites were fabricated via melt mixing followed by hot pressing technique. These were characterized using X-ray diffraction, thermo gravimetric, thermo mechanical, differential scanning calorimetry, fourier transform infrared (FTIR) and Impedance analyser for their structural, thermal and dielectric properties. Composites were found to have better thermal stability than that of pure PMMA. However, there was no significant difference in the glass transition (T ) temperature between the polymer and the composite. The appearance of additional vibrational frequencies in the range 400-600 cm in FTIR spectra indicated a possible interaction between PMMA and CCTO. The composite, with 38 vol% of CCTO (in PMMA), exhibited remarkably low dielectric loss at high frequencies and the low-frequency relaxation is attributed to the interfacial polarization/MWS effect. The origin of AC conductivity particularly in the high-frequency region was attributed to the electronic polarization. [ABSTRACT FROM AUTHOR]

This study focuses on the thermal and mineralogical transformations of clay ceramic pastes. The pastes contain different amounts of sugarcane bagasse ash waste. Thermal and mineralogical changes occurring during firing were characterized by differential thermal analysis, thermogravimetry analysis (TG), X-ray diffraction (XRD), and scanning electron microscopy. On heating three endothermic events within the 73.5-75.7, 276.9-283.5, and 567.1-573.5 °C temperature ranges were identified. The endothermic valleys could be mainly interpreted as the release of physically adsorbed water, dehydration of hydroxides, and dehydroxylation of kaolinite, respectively. Two exothermic events within the 618.9-690.1 and 948 °C temperature ranges were identified. The exothermic peaks are associated with the decomposition of organic compounds and crystallization of mullite from metakaolinite, respectively. TG results indicate that the clay ceramic pastes had a total mass loss in the 13.1-13.6 % range, and are dependent on the sugarcane bagasse ash waste amount added. It was found that the replacement of natural clay with sugarcane bagasse ash waste, in the range up to 20 wt%, influenced the thermal behavior and technological properties of the clay ceramic pastes. In addition, the thermal analysis results agree well with the XRD. [ABSTRACT FROM AUTHOR]

Polylactide (PLA)/starch blend/clay and PLA/clay composites are prepared by melt blending. Structural and thermal characterizations are performed by differential scanning calorimetry, X-ray diffraction analysis, and thermogravimetric analysis. The fire properties are assessed on a dual cone calorimeter. Combustion residue and char formation is characterized by optical microscopy and attenuated total reflection infrared spectroscopy. Although the clay is not fully intercalated/exfoliated, the composites exhibit a higher thermal stability and much reduced peak heat release rate, and the PLA/starch blend composite retains its mechanical properties. For the PLA/starch blend composite, smoke release is also considerably reduced. Catalyzed, oxidative decomposition is shown to occur early in the thermal decomposition of the composites, prior to increased thermal stability. The inclusion of clay promotes char formation and increases the quantity of carbonaceous char in the combustion residue. There is minimal migration of the clay to the surface prior to ignition and char is formed mainly after ignition and during burning. During the later stages of burning some of the char formed is converted to CO. [ABSTRACT FROM AUTHOR]

The isothermal and non-isothermal decompositions of cellulose nanofiber (CNF) and microfibrillated cellulose (MFC)-filled polypropylene (PP) composites were evaluated and compared with microcrystalline cellulose (MCC)-filled composites by means of thermogravimetric analysis (TG). X-ray diffraction was employed to evaluate crystallinity of the composites. The degree of maximum thermal degradation (ultimate DTG peak value) increased and thermal degradation onset temperature decreased as the cellulose content increased because the thermal stability of cellulose fillers is lower than that of neat PP, but the thermal degradation of the composite was hindered at higher temperature conditions because of the increased residual mass content of the cellulose nanofibril fillers compared to the matrix polymer. The isothermal residual mass of the cellulose nanofibril-filled PP composites under melt blending and injection molding temperatures was decreased marginally by incorporation of the cellulose reinforcement but still exhibited considerable isothermal stability. The raw materials and composites examined in this study were not affected by the manufacturing process temperatures utilized to produce the composites. The MCC decreased the composite crystallinity while the nano-sized cellulose (CNF and MFC) did not appear to have an effect on crystallinity. [ABSTRACT FROM AUTHOR]

Thermal properties of [ cis-(dithiocyanato)(4,5-diazafluoren-9-one)(4,4′-dicarboxy-2,2′-bipyridyl)ruthenium(II)], [Ru( L)( L)(NCS)] (where the ligands L = 4,5-diazafluoren-9-one, L = 4,4′-dicarboxy-2,2′-bipyridyl) have been investigated by DTA/TG/DTG measurements under inert atmosphere in the temperature range of 30-1155 °C. The mass spectroscopy technique has been used to identify the products during pyrolytic decomposition. The pyrolytic final products have been analyzed by X-ray powder diffraction technique. A decomposition mechanism has been also suggested for the cis-[Ru( L)( L)(NCS)] complex based on the results of thermogravimetrical and mass analysis. The values of the activation energy, E* have been obtained by using model-free Kissenger-Akahira-Sunose and Flyn-Wall-Ozawa non-isothermal methods for all decomposition stages. Thirteen kinetic model equations have been tested for selecting the best reaction models. The best model equations have been determined as A2, A3, D1, and D2 which correspond to nucleation and growth mechanism for A2 and A3 and diffusion mechanism for D1 and D2. The optimized average values of E* are 31.35, 58.48, 120.85, and 120.56 kJ mol calculated by using the best model equations for four decomposition stages, respectively. Also, the average Arrhenius factor, A, has been obtained as 2.21, 2.61, 2.52, and 2.21 kJ mol using the best model equation for four decomposition stages, respectively. The Δ H*, Δ S*, and Δ G* functions have been calculated using the optimized values. [ABSTRACT FROM AUTHOR]

BiTe nanoparticles (NPs) have been synthesized at 50 °C by a low-cost wet chemical route. The structural properties of product sample were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy. Thermal properties of product sample were investigated by differential scanning calorimetry (DSC), thermogravimetric (TG), and transient plane source techniques. The XRD and selected area electron diffraction of BiTe NPs result showed the polycrystalline nature with a rhombohedral ( R3 m) structure of the nanocrystallites. The average grain size of BiTe NPs was found to be about 30 nm by XRD and TEM measurements. DSC result shows one endothermic peak and one exothermic peak. TG result shows that only 48 % mass loss has occurred in BiTe sample. The obtained lower thermal conductivity of BiTe NPs is about 0.3 W m K at room temperature, which is caused by considering the crystalline nature of this material. [ABSTRACT FROM AUTHOR]

Polycrystalline ceramic samples of BiSnTiO ( x = 0.0, 0.2, 0.4, 0.6, 0.8) have been synthesized by conventional solid-state reaction method. The effect of homovalent cation (titanium) substitution on the Sn-site on the structural, morphological, electrical and thermal properties of the pure BiSnO ceramics have been studied by X-ray diffraction (XRD) followed by scanning electron microscopic techniques, dc conductivity and modulated differential scanning calorimetry. The XRD analysis carried out by performing the Rietveld refinement using the space group Fd3m indicates that the increase of titanium contents do not lead to any secondary phase. The grain size distributions of all the samples were investigated by SEM. It was found that the grain sizes are strongly influenced by the addition of titanium to the system. The frequency and temperature dependent dielectric studies have been carried out. The dc conductivity measurement was carried out for all the compounds and the activation energies were calculated using the relation σ = σ0 exp(− E/ kT). The modulated differential scanning calorimetry has been used to investigate the effect of substitution on the specific heat, heat flow and other thermal parameters of the compounds. The results are discussed in detail. [ABSTRACT FROM AUTHOR]

Chemical looping combustion (CLC) is a novel combustion technology with the capability for segregation of exhaust products (i.e., carbon dioxide/HO or N/O). The combustion is performed in two interconnected reactors with a solid oxygen carrier circulating between them, transferring oxygen from the air to the fuel. The feasibility of a successful CLC system depends on the selection of an appropriate oxygen carrier. Cu-based oxygen carriers are good oxygen carriers due to high reactivity. However, it faces low melting point, agglomeration problems in fluidized bed. In this study, a circular reduction-oxidation reaction simulated to the cyclic operation of the Cu-based oxygen carrier was conducted on the thermogravimetric analyzer (TG). The thermal behaviors of the potential Cu-based oxygen carrier were investigated by using an X-ray diffraction (XRD), scanning electron microscope (SEM), and surface analyzer. Multiple TG results show that the weight loss was 3.4%, indicating that the loading CuO amount was 17%. Moreover, the weight loss and weight gain was equal during 73 redox cycles, suggesting the good thermal stability of the oxygen carrier. The conversion rate of reduction and oxidation for each redox cycle remained constant even after 73 redox cycles. XRD results show the new phase formation of CuAlO during redox cycles, which promotes the thermal stabilization of the oxygen carrier. The surface area of the oxygen carrier decreased from 105 to 13 mg after 73 redox cycles and the particle size distribution shifted from 5-15 nm to 15-30 nm, suggesting that the micorpores were blocked or collapsed. However, the reactivity of the oxygen carrier didn't decrease. SEM results show that CuO was evenly distributed on the surface of AlO after 73 redox cycles. Overall, these results suggested that the Cu-based oxygen carrier was ready for fluidized bed tests. [ABSTRACT FROM AUTHOR]

Acid leaching of vermiculite is an interesting procedure to prepare high surface area porous silica. Thermal behaviour of unground and ground vermiculite leached with HCl solutions has been studied by TG, DTA, ETA and high temperature XRD. Important differences have been observed in the thermal behaviour of unground and ground vermiculite after the acid treatments. Thus, for the acid-treated unground vermiculite, dehydrated vermiculite, enstatite and cristobalite were formed during the heating, while for the acid-treated ground vermiculite only iron oxides and cristobalite phases were observed. Structural modifications due to acid treatment were responsible for changes in the transport properties determined by ETA for the vermiculite samples. [ABSTRACT FROM AUTHOR]

Heterobimetallic oxalato complex precursors, manganese(II)tetraaquatris(oxalato)lanthanate(III)hexahydrate (MnOLa), cobalt(II)pentaaquatris(oxalato)lanthanate(III)trihydrate (CoOLa), nickel(II)pentaaquatris(oxalato)lanthanate(III)hexahydrate (NiOLa) and copper(II)diaaquatris(oxalato)lanthanate(III)monohydrate (CuOLa) of the type, M[La(CO)(HO)]· nHO have been synthesized in aqueous medium. The precursors were characterized by elemental analysis, IR, electronic spectral and powder X-ray diffraction studies. The good crystalline nature with monoclinic structures predominates in MnOLa and NiOLa whereas triclinic structures were found in CoOLa and CuOLa. The solid-state thermal behaviour of the precursors was explored using TG, DTG and DTA in air. The MnOLa generated a mixture species consisting mainly of MnO, MnO, MnO, LaO and LaMnO at 1000 °C through the formation of several intermediate species at 380 and 570 °C. The studies revealed that CoOLa led mainly to LaCoO and LaCoO along with some oxides of both the cobalt and lanthanum at 1000 °C. In case of nickel analogue the mixture species identified at 1000 °C are mainly of LaNiO, LaO, NiO and NiO In case of CuOLa the product at 1000 °C consisted of LaCuO, LaCuO and oxides of copper and lanthanum. The nature of decomposition of the precursors in nitrogen were seen from DSC study and the kinetic parameters i.e., E, ln k, Δ H, Δ S and order of reaction of all the steps were evaluated and discussed. [ABSTRACT FROM AUTHOR]

Hematite with different particle sizes was obtained through isothermal annealing and mechanochemical ball-milling methods. The hematite phase is very stable under air atmosphere. The thermal stabilities of hematite under argon atmosphere were characterized by thermal analysis studies up to 800 °C using a simultaneous DSC-TG technique. The lattice parameters a and c of hematite with different particle sizes were extracted from the Rietveld structural refinement of powder X-ray diffraction patterns. Decomposition of hematite into a lower oxidation state in inert argon atmosphere was studied by the TG experiments for the first time and the enthalpy associated with the decomposition reaction was determined from the DSC studies. Particle size has a strong effect on the thermal behavior of hematite samples. Ball-milled hematite samples with smaller particle size showed that the phase transformation was extended to higher temperature range with larger enthalpy. Hematite with larger average particle size showed higher stability under argon atmosphere. [ABSTRACT FROM AUTHOR]

In this study, we have studied the stability of TiO-CdSe nanocomposites in which the individual moieties are linked using a bifunctional linker (mercaptopropionic acid). Nanoparticles of TiO and CdSe are synthesized by sol-gel and one pot methods. The equimolar amount of the above particles is utilized to prepare nanocomposites with and without linker. These samples are characterized for their structural, thermal, and optical properties using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infra-red spectroscopy (FTIR), and UV-Vis spectroscopy. The average particle size of TiO and CdSe are 16 and 23 nm, respectively. The addition of a bifunctional linker shows remarkable effect on the properties of TiO-CdSe nanocomposites. [ABSTRACT FROM AUTHOR]

The Pb(IO) crystals have been grown in sodium meta silicate gel using the single diffusion method at room temperature. The grown crystals were characterized by thermo analytical techniques (TG, DTA, and DTG), X-ray powder diffraction (XRD), and FTIR spectroscopy. The crystal system is confirmed to be orthorhombic having lattice parameters a = 6.09 Å, b = 16.68 Å, and c = 5.58 Å by powder X-ray diffraction analysis. FTIR study reveals that lead iodate crystal is anhydrous. TG, DTA, and DTG analysis shows a remarkable thermal stability. [ABSTRACT FROM AUTHOR]

This article studied the thermal behavior and the evolution of the crystalline phases with temperature of the red mud (bauxite tailing) from an aluminum industry at Maranhão, North-Northwestern Brazil. The experiments were carried out by Field Emission Scanning Electron Microscopy (FE-SEM), Simultaneous Thermal Analysis (TG-DSC), Optical Dilatometry up to 1623 K, and X-ray diffraction (XRD) of previously heated samples between 523 and 1523 K. The crystalline phases and the amorphous contents were quantified on raw and heated samples (at 1523 K) according to the Rietveld Quantitative Analysis (RQA) method. The data obtained showed that the raw red mud is composed by a mixture of seven different phases (hematite, goethite, sodalite, anatase, gibbsite, calcite, and amorphous). Finally in the interval of 1023-1523 K the following crystalline phases: hematite, nepheline, sodalite, anatase, perovskite, and pseudobrookite have been observed. [ABSTRACT FROM AUTHOR]

Thermal and structural properties of three clays (sepiolite and two kaolinites) from Turkey were studied by thermal analysis (TG-DTA), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FT-IR), and surface area measurement techniques The adsorption of sulfur dioxide (SO) gas by these clays was also investigated. SO adsorption values of K1, K2, and S clay samples were measured at 20 °C and pressures up to 106 kPa. Sepiolite sample (S) primarily consists of pure sepiolite, only dolomite present as accompanying mineral. Both kaolinite samples, K1 and K2, mainly contain kaolinite as the major clay mineral and quartz as impurity. In K2 sample, muscovite phase is also present. Simultaneous TG-DTA curves of all clay samples were obtained at three different heating rates 10, 15, and 20 °C min over the temperature range 30-1200 °C. It was found that the retention value of SO by S clay (2.744 mmol/g) was higher than those of K1 (0.144 mmol/g) and K2 (0.164 mmol/g) samples. [ABSTRACT FROM AUTHOR]

For a comparison of structural data and thermal behaviour of Zn(II) and Cd(II) complexes with biologically important ligand, 2-hydroxymethylbenzimidazole (L) the complex of the formula [ZnL](NO)LL′ was prepared and characterized by elemental analysis, infrared (IR) spectra, single-crystal X-ray diffraction and thermal analysis (where L′ = 2-carbaldehydebenzimidazole). IR and X-ray studies have confirmed a bidentate fashion of coordination of the 2-hydroxymethylbenzimidazole to Zn(II) ion (through the nitrogen atom of heteroaromatic ring and oxygen atom of hydroxymethyl group). The zinc ion is hexacoordinated and the shape of polyhedron can be described as pseudo-octahedron (NO chromophore type). The decomposition process of studied Zn(II) and Cd(II) benzimidazole complexes in the air atmosphere proceeds in three or four main stages and traces structures of complexes. On the basis of the first DTG of the decompositions the thermal stability of the complexes follows the order: [CdL](NO)LEtOH < [CdL(NO)] < [ZnL](NO)LL′. As the final solid products of thermal decomposition suitable metal oxides are formed. [ABSTRACT FROM AUTHOR]

Dysprosium hafnate is a candidate material for as control rods in nuclear reactor because dysprosium (Dy) and hafnium (Hf) have very high absorption cross-sections for neutrons. Dysprosium hafnate (Dy2O3·2HfO2-fluorite phase solid solution) was prepared by solid-state as well as wet chemical routes. The fluorite phase of the compound was characterized by using X-ray diffraction (XRD). Thermal expansion characteristics were studied using high temperature X-ray diffraction (HTXRD) in the temperature range 298–1973 K. Heat capacity measurements of dysprosium hafnate were carried out using differential scanning calorimetry (DSC) in the temperature range 298–800 K. The room temperature lattice parameter and the coefficient of thermal expansion are 0.5194 nm and 7.69 × 10−6 K−1, respectively. The heat capacity value at 298 K is 232 J mol−1 K−1. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to study the thermal behaviour of (50- x)Na2O- xTiO2-50P2O5 and 45Na2O-yTiO2-(55- y)P2O5 glasses. The addition of TiO2 to the starting glasses ( x=0 and y=5 mol% TiO2) resulted in a nonlinear increase of glass transition temperature and dilatation softening temperature, whereas the thermal expansion coefficient decreased. All prepared glasses crystallize under heating within the temperature range of 300–610°C. The contribution of the surface crystallization mechanism over the internal one increases with increasing TiO2 content. With increasing TiO2 content the temperature of maximum nucleation rate is also gradually shifted from a value close to the glass transition temperature towards the crystallization temperature. X-ray diffraction measurements showed that the major compounds formed by glass crystallization were NaPO3, TiP2O7 and NaTi2(PO4)3. The chemical durability of the glasses without titanium oxide is very poor, but with the replacement of Na2O or P2O5 by TiO2, it increases sharply. [ABSTRACT FROM AUTHOR]

Structural and thermal properties of the 20Li2O-80TeO2 glass were studied using X-ray diffraction analysis and differential scanning calorimetry techniques to understand and control the crystallization process on this glass. The γ-TeO2, α-TeO2 and α-Li2Te2O5 phases were identified during the crystallization in this glass. Activation energies and Avrami exponent n were calculated from non-isothermal measurements for glasses with different particle size. The mean values $$ \bar n $$ of Avrami exponent were obtained for glasses with 63–75 and 45–63 μm particle sizes such as $$ \bar n_1 < \bar n_2 < \bar n_3 $$, but glasses with particle size 38–45 μm and smaller than 38 g,m presented $$ \bar n_1 \approx \bar n_2 < \bar n_3 $$. [ABSTRACT FROM AUTHOR]

Hybrid materials were prepared by γ-irradiation of a mixture of polydimethylsiloxane (PDMS), with tetraethylorthosilicate (TEOS) and zirconium propoxide (PrZr), using a 60Co γ source, without any addition of solvents. Thermogravimetry, differential scanning calorimetry and X-ray diffraction measurements showed that the obtained hybrids are amorphous materials of the nanocomposite type. The results highlighted the different influence of each of the metallic alkoxides on the hybrid structure. The material rupture temperature, associated with the degradation of the organic component, depends mainly on the TEOS content, whereas the inorganic component structural stability depends on the relative PrZr content in the alkoxides mixture. [ABSTRACT FROM AUTHOR]

We studied the thermal stability of different hexagonal tungsten trioxide, h-WO3 samples, which were prepared either by annealing hexagonal ammonium tungsten bronze, (NH4)0.33−xWO3−y, or by soft chemical synthesis from Na2WO4. The structure and composition of the samples were studied by powder XRD, SEM-EDX, XPS and 1H-MAS NMR. The thermal properties were investigated by simultaneous TG/DTA, on-line evolved gas analysis (TG/DAT-MS), SEM and in situ powder XRD. The preparative routes influenced the thermal properties of h-WO3 samples, i.e. the course of water release, the exothermic collapse of the hexagonal framework and the phase transformations were all affected. [ABSTRACT FROM AUTHOR]

The investigations by XRD, DTA/TG and IR methods show that two compounds: ZnSb2O6 and Zn7Sb2O12 are formed in the ZnO-α-Sb2O4 system in air. Oxygen contained in the air participates in the synthesis of these compounds. ZnSb2O6 was observed as an intermediate phase, during the Zn7Sb2O12 synthesis. The temperature of the β→α-Zn7Sb2O12 transition was fixed at 1225±10°C. The mechanisms of the reactions of ZnSb2O6 and Zn7Sb2O12 thermal decomposition have been proposed. The IR studies of α and β-Zn7Sb2O12 have initially indicated that the structures of both polymorphous forms differ in the reciprocal connection of the SbO6 and ZnO6 octahedra and the ZnO4 tetrahedra. [ABSTRACT FROM AUTHOR]