Differential Thermal Analysis Curves Research Articles

Високотемпературне уреатне мастило для авіаційної техніки

Мета: Представлені результати досліджень особливостей синтезу багатоцільового уреатного мастила на синтетичних оливах для широкого температурного діапазону застосування, придатного для використання у авіаційній техніці. Методи: Взаємодією поліізоціанату з октадециламіном та бензиламіном у суміші поліальфаолефінової оливи з естерами пентаерітриту і жирних кислот фракції С5-С9 синтезовано полісечовину – загусник уреатних мастил. Її будова встановлена методом ІЧ-спектроскопії. Для визначення верхньої температурної межі застосування мастила використано метод дериватографічного аналізу. Властивості мастила досліджені стандартними методами. Результати: ІЧ-спектри уреатного мастила засвідчили, що застосоване для синтезу загусника співвідношення реагентів призводить до повного їх витрачання у ході реакції та дозволяє одержати сечовину з максимальним виходом. Характер кривих диференціального термічного аналізу та термогравіметрії вказує, що верхня температурна межа застосування уреатного мастила, виготовленого на суміші синтетичних олив, знаходиться на рівні 200 оС. Встановлено, що температура синтезу і співвідношення компонентів загусника визначають термічні, реологічні та механічні властивості системи. Варіюючи мольним співвідношенням компонентів сечовинного загусника, вдалося створити механічно та колоїдно стабільну мастильну композицію. Мастило не застигає до мінус 50 оС, що підтверджується низькою в’язкістю за цієї температури та величиною крутних моментів на початку та за сталого обертання підшипника. Застосування багатофункціонального пакету присадок дозволило вийти на новий якісний рівень за трибологічними характеристиками і стійкістю до окиснювальних перетворень. Обговорення: Дослідження засвідчили, що властивості уреатного мастила залежать не тільки від природи і співвідношення компонентів сечовинного загусника та параметрів процесу його синтезу, але й від збалансованості мастильної композиції в цілому з правильно підібраними базовими оливами та пакетом присадок. Розроблений продукт з високим рівнем трибологічних, антиокислювальних та екологічних характеристик відповідає сучасним вимогам до авіаційних мастил і може бути рекомендований для застосування в жорстких умовах експлуатації в широкому температурному діапазоні.

Evaluation of thermal behavior and chromatographic characterization of oil extracted from seed of Pittosporum undulatum

The composition of the oil extracted from sweet pittosporum was studied by chromatography analyses. The sweet pittosporum (Pittosporum undulatum) is native to eastern parts of Australia. It is a tree growing to 15 m tall with wavy (undulating) leaf edges and also has attractive fragrant flowers, sweet pittosporum and is found in southern Brazil. The chromatographic profile of this oil reveals a predominance of unsaturated fatty acids, in particular, 28.86% of cis-11-eicosenoic acid (C20:1), 31.44% of eicosatrienoic acid (C20:3n3), 6.61% of docosahexaenoic acid (C22:6n3) and 24.32% of oleic acid (C18:1n9). This oil was characterized by differential scanning calorimetry (DSC), from 100 to − 80 °C and subsequently heated from − 80 °C up to 100 °C, both at cooling/heating rate of 1 and 10 °C min−1. Thermogravimetry (TG) and differential thermal analysis (DTA) in nitrogen and oxygen purge gases under different heating rates show oil stability. The analysis carried out by DSC indicates that this oil has two crystallization peaks under cooling condition. Simultaneous TG–DTA curves show that the behavior of this oil shows variation among the heating rates, with a sudden combustion. The kinetic behavior showed the relationship between the uses of two sample masses, with good parameter and high correlation coefficients (r).

Thermal decomposition behavior and thermal stability of DABT·2DMSO

The thermal decomposition behavior and thermal stability of 3,3′-diamino-5,5′-bis(1H-1,2,4-triazole) with 2DMSO (DABT·2DMSO) were investigated by thermo gravimetry–derivative thermo gravimetry–differential scanning calorimetry (TG–DTG–DSC), differential thermal analysis (DTA) and accelerating rate calorimeter (ARC). The result of TG–DTG–DSC at a heating rate of 10 °C min−1 indicated that an endothermic decomposition and an exothermic decomposition occurred at 388.23 and 468.23 °C, respectively. The apparent activation energy (E a) and pre-exponential factor (A) of the exothermic decomposition, and the free energy of activation, activation enthalpy and activation entropy at initial decomposition temperature (T p0) were calculated from the DTA curves recorded at heating rates of 1, 2, 4, 8 °C min−1. The critical temperature of thermal explosion (T bp0) obtained by the Ozawa’s and Kissinger’s methods were calculated as 470.46 and 470.73 °C, respectively. The result of ARC indicated that the self-heating decomposition started at 443.61 °C and ended at 480.91 °C, within the time span of 1397.50 min. The self-heating decomposition parameters, including the onset temperature, final temperature, temperature at max rate, max temperature rate, adiabatic temperature rise and time to maximum rate were obtained, and these parameters were corrected by thermal inertia factor. The E a and A under adiabatic condition were also calculated. In addition, the self-accelerating decomposition temperature (T SADT, 50kg) was calculated as 429.54 °C.

Synthesis and Characterization of Highly-Conducting Nanocrystallized Li(Fe1–xMnx)0.88V0.08PO4 Cathode Materials (x = 0.25, 0.5, 0.75)

INTRODUCTION Since the pioneering publication by J.B. Goodenough et al. [1], phospho-olivines LiMPO4 (M = Fe, Mn, Co, Ni) had been studied for their application as cathodes for Li-ion cells. From the whole family of isostructural compounds, only cathodes prepared from LiFePO4 had been introduced into mass production. LiMnPO4 has higher potential versus metallic lithium compared to LiFePO4, but synthesis of LiMnPO4 compounds which can work in batteries with high loads is more difficult [2]. One of the successful synthetic routes consists in preparation of intentionally non-stoichiometric compositions [3]. Other possible way is to synthesize LiMn1–xFexPO4 phospho-olivines [4, 5]. In recent years, our group has proposed and investigated an alternative route to the conductivity enhancement, namely a thermal nanocrystallization of glassy analogs of the important crystalline cathode materials, such as: V2O5, LiFePO4 and Li3V2(PO4)3 [6, 7]. The advantages of this approach include the absence of carbon additives, simplicity and straightforwardness of synthesis, which consists of two stages only: (i) glass preparation by melt-quenching and (ii) thermal treatment of the glass to induce its nanocrystallization. Our experience with that method has shown that one can, by the appropriate heat-treatment, achieve a gigantic (even by a factor 109) and irreversible conductivity enhancement. EXPERIMENTAL In this research, we aimed to replace some of iron ions in LiFe0.88V0.08PO4 glass with manganese in order to obtain highly conductive nanomaterials. Appropriate amounts of precursors: Li2CO3, FeC2O4·2H2O, Mn(CH3COO)2·4H2O, (NH4)H2PO4 and V2O5 were mixed in a mortar, melted at 1300°C in reducing atmosphere and rapidly quenched. Their amorphousness was confirmed with X-ray diffractometry (XRD) and thermal events occurring in the samples were observed with differential thermal analysis (DTA). Electrical conductivity was measured upon heating and subsequent cooling ramps with impedance spectroscopy within wide frequency range 10 mHz – 10 MHz. RESULTS AND DISCUSSION DTA curves of as-received samples were typical for glassy materials. A glass transition and two crystallization peaks were observed. Preliminary electrical results (Fig. 1) showed that initial conductivity (1.2·10–13 S/cm) can be increased of at least 10 orders of magnitude to ca 10–3 S/cm. XRD patterns acquired upon heating to 580°C indicated three crystalline phases: triphylite LiFePO4, lithiophilite LiMnPO4 and lithium iron phosphate Li3Fe2(PO4)3. All of the three structures are electrochemically active and therefore are suitable to be used as cathodes in Li-ion batteries. CONCLUSIONS This research has shown that thermal nanocrystallization of glassy analogs of LiFe1–xMnxPO4 resulted in highly conducting materials that may be used as a cathode in Li-ion battery. The addition of vanadium was to improve its glass forming properties and to provide favorable conditions for electron hopping in the nanomaterials. ReferenceS A.K. Padhi, K.S. Nanjundaswamy, J.B. Goodenough, Journal of the Electrochemical Society 144 (1997) 1188–1194. J.O. Herrera, H. Camacho-Montes, L.E. Fuentes, L. lvarez-Contreras, Journal of Materials Science and Chemical Engineering 3 (2015) 54–64. B. Kang, G. Ceder, Journal of The Electrochemical Society 157 (2010) A808–A811. L. Damen, F. De Giorgio, S. Monaco, F. Veronesi, M. Mastragostino, Journal of Power Sources 218 (2012) 250–253. J. Molenda, W. Ojczyk, J. Marzec, Journal of Power Sources 174 (2007) 689–694. J.E. Garbarczyk, T.K. Pietrzak, M. Wasiucionek, A. Kaleta, A. Dorau, J.L. Nowinski, Solid State Ionics 272 (2015) 53–59. T.K. Pietrzak, M. Wasiucionek, P.P. Michalski, A. Kaleta, J.E. Garbarczyk, Materials Science and Engineering B 213 (2016) 140–147. Figure 1

Thermal properties of silica-coated cellulose fibers for increased fire-resistance

In this paper, two precipitation methods of silica, i.e., sol–gel method and silica polymer precipitation, were compared in terms of their impact on the thermal properties of impregnated cellulose fibers. Additionally, the pre-treatment process consisting in dipping the cellulose fibers in NaOH solution to increase the fibers porosity was examined. Three molar phosphoric acid and Flodur 3 (ester hardener based on ethylene glycol diacetate) were used as the sol–gel precipitation agents and 20 wt% aqueous solution of sodium acrylate was used as the polymer precipitation agent. The silica provider was sodium water glass type D. The obtained results have shown that the silicate layer fully covered the cellulose fibers, as confirmed by the scanning electron microscope microphotographs and mid-infrared spectra. Even after thermal treatment at 700 °C, the silicate species still remained in the ash as confirmed by the infrared bands characteristic for sodium silicates, i.e., at 960 and 880 cm−1. Thermogravimetric analysis revealed no significant difference in the weight loss of the cellulose samples treated with different precipitation mixtures, as well as between the raw and pre-treated samples. All weight losses oscillated between 40–50 wt% at 700 °C. Differential thermal analysis curves showed that the pre-treatment process shifts the temperature range in which the different phenomena occur towards higher values. We believe that these results could contribute to the development of cellulose materials with enhanced thermal properties and the process could be an attractive substitute for coatings based on orthosilicates and their derivatives.

DTA and FTIR of 70TeO2–(25 − x)MnO2–xV2O5–5Fe2O3 tellurite glass systems

A series of quaternary tellurite glasses in the form of 70TeO2–(25 − x)MnO2–xV2O5–Fe2O3 where (0 ≤ x ≤ 25 mol%) have been prepared by the conventional melt quenching technique. Differential thermal analysis (DTA) curves of these glasses have been investigated in the temperature range 300–1093 K and at different heating rates a = (2.5, 5, 10, 20 and 40 K min−1). The glass transition temperature (T g), the crystallization temperature (T P), the glass stability (∆T) and the activation energy for crystallization have been measured. The glass transition temperature has been analyzed according to the average cross-link density, and the average stretching force constant is present in the glass. FTIR investigations showed that the absorption bands of different modes of vibration in the manganese tellurite network were shifted toward higher wave number.

Evolution of ferroelectric SrBi2Nb2O9 phase embedded in tellurite glass

ABSTRACTGlasses with the composition, [(100-x)TeO2- x(SrO–Bi2O3–Nb2O5)] with x = 20, 30 and 40 (in mol %) were prepared. The X-ray diffraction (XRD) pattern and differential thermal analysis (DTA) for the as-prepared samples confirmed the amorphous and glassy characteristics, respectively. The SrBi2Nb2O9 phase in tellurite glass for HT773 sample at x = 40 mol % is formed and confirmed by the Rietveld refinement. DTA curves for all glass samples exhibit two endothermic dips while the two broad exothermic peaks at lower x reduced to one at higher x. Infrared (IR) results revealed that the glassy matrix are composed of TeO3, TeO3+1, TeO4, BiO6 and NbO6 structural units. The changes in the density (ρ), molar volume (Vm), oxygen molar volume (V0) and oxygen packing fraction (OPD) have correlated with structural changes in the glass network. The optical studies show an absorption bands below the absorption edge in the glass samples.

Comparative research of plasma-assisted milling and traditional milling in synthesizing AlN

In this paper, traditional milling and discharge plasma-assisted milling are employed to synthesize aluminum nitride (AlN) powder at nanometer scale by milling the mixture of aluminum and lithium hydroxide monohydrate. AlN powders can be generated in traditional milling and plasma-assisted milling in an hour milling time. Differential thermal analysis curves show that the reaction temperature of the powders treated by plasma-assisted milling is lower than that of traditional milling. These results indicate that plasma-assisted milling has higher efficiency in the synthesis of AlN, getting smaller crystallite size and activating powder. Moreover, an optical emission spectrum is employed to demonstrate the active species in plasma. The different formation process of AlN in the two-milling process, and the promotion effects of plasma in the milling process are discussed.

The challenge of methods of thermal analysis in solid state and materials chemistry

Abstract Thermogravimetry (TG) and differential thermal analysis (DTA) are traditional, but still useful, experimental techniques for obtaining information in the realms of materials and solid state chemistry. This paper presents two case studies (many more could be cited) to illustrate the strengths (and limitations) of these techniques: (1) Iron doping of clinoptilolite (the most common zeolite): the typical parameters of both components appear clearly in the TG and DTA curves. The decrease of the Tmax value of the structurally-typical DTA effect of FeOOH by approximately 100°C is attributed to the weakening of chemical bonds in FeOOH due to the incorporation of the doping component into the structure of this zeolite. (2) Macrodefect-free (MDF) materials: the results of both TG and DTA unambiguously locate the typical temperature range of the decomposition of the P{4}–O–Al/Fe{6} cross-links within the interval of 200–300°C. The presence of cross-links is shown by the DTA data while the TG data can be used to measure the degree of cross-linking, which is valuable information when studying both raw mixes and the final materials for a variety of MDF materials.

Thermal behavior and dehydration kinetic study of SiO2/PEG hybrid gel glasses

Six different silica‐polyethylene glycol (SiO2/PEG) organic‐inorganic hybrid nanocomposites with different amounts of PEG 400 (6, 12, 24, 50, 60 and 70 wt.%) were synthesized by the sol‐gel technique. Their thermal behavior was studied by thermogravimetry (TG) and differential thermal analysis (DTA) under a flowing argon atmosphere in a wide temperature range and their behavior was compared with those of the related materials with 60 and 70 wt.% of PEG, whose results were reported in a previously study. To identify all physical and chemical processes occurring in these promising materials, the gases evolved during TG experiments were analyzed at characteristic constant temperatures by FTIR. These measurements revealed that all the materials undergo a two‐step dehydration (loosing water physically bound at temperature lower than 100°C) with overlapping of both TG and DTA curves, thus suggesting an identical behavior up to 200°C regardless the different content of PEG. A different behavior is observed at higher temperature, where three different exothermic effects were observed in the range 200–450°C accompanied by mass losses ranging from 6 to 37% for the SiO2/PEG hybrid materials. POLYM. ENG. SCI., 57:606–612, 2017. © 2017 Society of Plastics Engineers

Thermoanalytical characterization of herbal drugs from Poincianella pyramidalis in different particle sizes

Poincianella pyramidalis (Tul.) L.P. Queiroz, known as “catingueira,” is a typical species of Caatinga and used in Brazilian folk medicine as anti-inflammatory, antipyretic, diuretic and expectorant. Pharmacological analyses confirmed his activity as anti-inflammatory, antimicrobial and in gastrointestinal disorders. This paper aimed to perform a thermoanalytical characterization of the herbal drugs obtained from P. pyramidalis leaves in different particle sizes. The leaves were dried, pulverized and separated into different granulometric ranges: 50–100, 100–200, 200–400 and <400 mesh. The samples were characterized by thermogravimetry (TG) at different atmospheres and heating rates, determination of the kinetic degradation parameters by Ozawa model, differential thermal analysis (DTA), pyrolysis coupled to gas chromatography interfaced with mass spectrometry (Pyr-GC/MS) and multivariate analysis. TG curves of the samples showed the presence of six thermal decomposition events, with greater mass loss (25.91–35.66%) in the range of 247–398 °C. The thermal degradation proved to be a reaction of zero order, with a decrease in enthalpy and frequency factor with decreasing the granulometric range. DTA curves showed three exothermic events, with peaks around 350, 460 and 490 °C, with variation in enthalpy values. With the Pyr-GC/MS were evidenced different profiles according to the temperature. Principal component analysis of pyrolysis data from samples at different temperatures was able to represent the total variability within the first two principal components, revealing differences between the granulometric ranges. The analytical and statistical techniques used were able to trace characteristic profiles of the herbal drugs, elucidating the differences in each granulometric range.

Investigation and evaluation of the glass stability criteria for Se60Ge15X25 (X = Sn, As) compositions

Study of the glass stability for amorphous Se60Ge15X25 (X = Sn, As) compositions has been performed by determination and evaluation of the widely used and more recently glass stability (GS) criteria. Calorimetric differential thermal analysis (DTA) measurements have been used under non-isothermal conditions at different heating rates. GS criteria have been determined based on the interrelationship of the estimated characteristic temperatures from DTA curves. All GS criteria are found to be heating rate and composition dependence. Their values and behaviors indicated that the most stable composition against devitrification with As addition. The calculated criteria values based on the onset crystallization temperature Tx and the maximum (peak) crystallization temperature Tc exhibit a similar behavior as a function of heating rate and composition, whereas both of them have incompatible values. The relative change parameter of GS criteria as well as their heating rate and composition dependence reflects that the more suitable and sensitive GS criterion, for the studied compositions, is Saad and Poulain’s criterion Ks and the less one is Lu and Liu’s criterion KLL for two studied compositions.

Effects of melting temperature on cerium oxidation state and crystallization on catalytic properties in cerium phosphate glasses

The effect of the melting temperature on the cerium oxidation state and crystallization of cerium phosphate glasses with a molar composition 30CeO2–70P2O5 was investigated. Ce3+ and Ce4+ ion concentration changes in the glass attributable to the melting temperature were investigated by X-ray photoelectron spectroscopy analysis. The crystallization kinetics of the glasses and the activation energy for crystallization were evaluated under non-isothermal conditions using differential thermal analysis (DTA) performed at different heating rates. Each DTA curve exhibited one exothermic peak associated with the crystallization of the glass. The crystalline phase was identified as CePO4 via X-ray diffractometry analysis. The Kissinger and Marotta methods were used to calculate the local activation energies for the glass samples. The amount of precipitated CePO4 with heating at 890 K increased as the melting temperature (or Ce3+) increased. The catalytic properties were studied by thermogravimetric analysis, which showed that a greater amount of precipitated CePO4 led to poorer catalytic properties of the glass.

Iron (III) oxide fabrication from natural clay with reference to phase transformation γ- → α-Fe2O3

Amorphous iron (III) oxide was obtained from clay, using ammonium hydroxide as a precipitating agent. Influence of freeze drying under vacuum, as a drying method, on particle size, chemical composition, and crystallinity of obtained iron (III) oxide powder was investigated. After freeze drying, precipitate was annealed in air at 500?C and 900?C. X-ray diffraction, particle size analysis, scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis were used to characterize obtained iron (III) oxide powder. All of three powders obtained by freeze drying and annealing, have low crystallinity and particles with irregular layered shape. Narrow particle size distribution was given by an average diameter value of around 50 ?m for all observed powders. Iron-bearing materials like ?-Fe2O3 and ?- Fe2O3 are obtained. Differential thermal analysis curve of obtained samples showed endothermic reaction at 620?C which could be ascribed to phase transition from cubic form ?- ? ?- Fe2O3. Thermal transformations of iron (III) oxide, obtained from clay as a natural source, is suitable to explore in the framework of materials chemistry, and opens the possibility to synthesize materials based on Fe2O3 with specific magnetic behavior.

Gadolinium Doped NaLaF4 Nanocrystals in Glass-Ceramics and Polycrystalline Powders

Gadolinium doped scintillators could be efficient neutron detectors with a minimal residual radioactivity and good temperature stability [1]. In this research we analyze localization and properties of Gd3+ dopants in oxyfluoride glass-ceramics containing NaLaF4 nanocrystals and in polycrystalline NaLaF4 powders. Glass samples with the composition 63SiO2-7Al2O3-16Na2CO3-9NaF-5LaF-0.1GdF3 were synthesized by the quench melting method and converted to glass-ceramics by the heat treatment technique. Heat treatment temperatures were selected according to the differential thermal analysis curves. Polycrystalline samples were prepared by solid state reaction method from NaF, LaF3 and GdF3 batch materials. GdF3 concentrations were varied from 0.01 to 1 mol%. NaLaF4 nanocrystals have been observed in glass-ceramics and polycrystalline samples by X-ray diffraction measurements. Photoluminescence and cathodoluminescence spectra show a peak around 315 nm, which originates from 6P7 /2 → 8S7/2 energy level transition of the Gd3+ ion. EPR measurements of the glass samples show the Gd3+ spectrum of disordered environment, however in glass-ceramics the EPR spectra have fine structure characteristic to the specific crystallite. EPR measurements of NaLaF4 powders with different concentrations of Gd3+ showed that the EPR spectrum consists of superposition of at least two paramagnetic centres. Reference [1] Watt, David Edwin, and Dennis Ramsden. High Sensitivity Counting Techniques: International Series of Monographs on Electronics and Instrumentation. Vol. 20. Elsevier, 2014. Acknowledgement Financial assistance to the first author from the Baltic-American Freedom Foundation is gratefully acknowledged.

A Study on Synthesis of Ni-Ti-B Alloy by Mechanical Alloying from Elemental Component Powder

A Ni-Ti-B alloy powder prepared by mechanical alloying (MA) of individual Ni, Ti, and B components is examined with the aim of elucidating the phase transitions and crystallization during heat treatment. Ti and B atoms penetrating into the Ni lattice result in a Ni (Ti, B) solid solution and an amorphous phase. Differential thermal analysis (DTA) reveals peaks related to the decomposition of the metastable Ni (Ti, B) solid solution and the separation of equilibrium , , and phases. The exothermal effects in the DTA curves move to lower temperatures with increasing milling time. The formation of a phase by annealing indicates that the mechanochemical reaction of the Ni-Ti-B alloy does not comply with the alloy composition in the ternary phase diagram, and Ti-B bonds are found to be more preferable than Ni-B bonds.

Influence of Sb2O3 on tellurite based glasses for photonic applications

Tellurite based ternary glasses with compositions TSW: 75TeO2–xSb2O3–(25−x)WO3 where x = 5, 10, 15, 20 mol% were prepared by conventional melt quenching and pressing method. The prepared samples were investigated by X-ray diffraction (XRD), Differential thermal analysis (DTA), UV-VIS absorption spectroscopy, Raman and Fourier transform-infrared (FTIR) spectroscopies. XRD patterns recorded at room temperature confirm the amorphous nature of the glasses. Thermal properties such as glass transition temperature (Tg) and thermal stability of the glasses were determined from the differential thermal analysis curves. The absorption edge of the glasses shifts towards lower wavelength with increasing antimony oxide content in the glass indicating the increase of rigidity of the glass. FTIR and Raman spectra of the glasses showed the existence of WO4, WO6, TeO4, TeO3, TeO3+1 and SbO3 structural units in the glass network. The gradual increase of antimony oxide content in the glass matrix causes the transformation of TeO4 structural units to TeO3 or TeO3+1. Energy band gaps (Eg) and Urbach energies (ΔE) of the glasses were obtained by using the optical absorption spectral data. Density, molar volume, oxygen molar volume and oxygen packing density (OPD) of the glass samples were calculated to evaluate the physical and structural properties of the glasses.

Crystallization kinetics and glass transition kinetics of iron borophosphate glass and CeO2-doped iron borophosphate compounds

Effects of CeO2 doping and the preexisting formed CePO4 crystallite on the crystallization kinetics and glass transition kinetics of the 36Fe2O310B2O354P2O5 glass (IBP glass) have been investigated by differential thermal analysis (DTA). The results reveal that a well defined glass transition peak and two crystallization peaks are observed in DTA curve of the IBP glass. The crystallization activation energies for the first crystallization peak (Ec for P1) and the second crystallization peak (Ec for P2) of the IBP glass are 211.77 KJ mol−1 and 564.31 KJ mol−1 respectively. And CeO2 doping insignificantly affects the Ec for P1 but increases the Ec for P2. Moreover, the preexisting CePO4 crystallite increases the Ec for P1 and the activation energies of glass transition peak (Eg). However, the CePO4 crystallite obviously decreases the Ec for P2. In addition, the crystal growth in the IBP glass occurs in two dimensions. Due to the preexisting CePO4, the dimensions of crystal growth in CeO2-doped IBP compounds change to three. The conclusions offer some useful information for the disposal of high-level radioactive wastes using iron borophosphate glasses and iron borophosphate based glass-ceramics.

Thermal behavior of the chlorophyll extract from a mixture of plants and seaweed

In this study the UV–Vis spectrophotometry and thermal analysis were used to characterize a commercialized product, as “Chlorophyll” named in our study with the acronym FARCH-phyll, this being offered as a detoxifier for the human body. The information update concerning thermal decomposition mechanism of chlorophyll represents the basic purpose of this investigation, and the secondary aim is related to the dealer prospectus confirmation. Thus, by the UV–Vis spectrophotometry, the chlorophyll “a,” was detected in FARCH-phyll extracts in both ethylic alcohol and dioxane showing two absorption bands at the wavelengths: λ = 664/428 nm and λ = 665/430 nm, respectively. The thermal decomposition of FARCH-phyll was performed in the temperature range between room temperature and 700 °C, and the thermogravimetric curve highlighting three levels of mass loss accompanied by one endothermic process at 54.8 °C and two exothermic processes at 333.6 and 492.2 °C, respectively, was marked on both curves of differential scanning calorimetry and differential thermal analysis. The first step of mass loss was accurately attributed to the releasing of physically adsorbed compounds on the powder surface. The next levels of powder thermal degradation constituted the basis for identifying the decomposition steps of chlorophyll from FARCH-phyll, in order to show its ways of transformation/decomposition in pheophytin/pyropheophytin and pyropheophorbide in competition with decomposition processes of other components from FARCH-phyll.

Studies on an L-leucine hydriodide semiorganic crystal for frequency conversion applications

An L-leucine hydriodide semiorganic crystal has been synthesized and grown by a slow evaporation technique. The lattice parameters of the grown crystal have been confirmed using single-crystal x-ray diffractometry. Various functional groups present in the crystal were identified by Fourier transform infrared (FTIR spectral) assessment. The optical transmission percentage of the crystal was ascertained by UV–vis-near-infrared (NIR) studies. The thermal stability of the crystal was determined by thermogravimetric and differential thermal analysis curves. The mechanical behavior of the crystal was studied using the Vicker’s microhardness analysis. The dielectric properties of the crystal have been investigated for varying temperatures. The second-harmonic generation efficiency was measured by the Kurtz and Perry powder technique and the efficiency is comparable to that of potassium dihydrogen orthophosphate.