Search results for "Differential Thermal Analysis"
showing 10 items of 66 documents
Injection molding of syndiotactic polystyrene/clay nanocomposites
2006
This study aims at exploring the effect of a commercial organoclay montmorillonite (MMT) on the final properties of syndiotactic polystyrene (sPS) injection-molded samples. To this goal, injection-molded specimens made from neat sPS and commercial MMT modified with various organic compounds were prepared in different molding conditions. Dispersion of clay was attained via melt blending, directly in the injection chamber of the injection-molding machine. The obtained specimens were analyzed by IR spectroscopy, X-ray diffraction, thermogravimetry, and differential thermal analysis, with the aim of elucidating the effect of clay on the microstructures of the samples. Results clearly show that,…
Rare Earth Activated Oxyfluoride Glasses and Glass-Ceramics for Scintillation Applications
2012
Oxyfluoride glasses 49SiO2·6Al2O3·24Li2O·20LaF3 activated with Tb, Ce, Eu have been synthesized and studied. After heating at 580°C and 750°C crystalline phases were obtained. The samples were studied by DTA (Differential thermal analyzer), CL (cathodoluminescence), XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy dispersive x-ray spectroscopy) methods. We found out that presence of crystalline phase enhances the CL of Tb activated samples significantly; whereas, the shortest decay time of 0.29 μs has been observed for less intense Ce doped glass sample.
New ferroelectric materials on the basis of PbSc1/2Nb1/2O3–PbLu1/2Nb1/2O3 solid solutions
2004
Abstract Original binary solid solutions PbSc 1/2 Nb 1/2 O 3 –PbLu 1/2 Nb 1/2 O 3 (PSN-PLuN) have been produced. First of all nominally pure PSN and PLuN were synthesized by solid state reaction from oxides and carbonates. These compounds were mixed in different proportions to obtain (1− x )PSN− x PLuN solid solutions. Ceramic samples were hot-pressed at gradual change of the temperature. Solid solutions have the perovskite structure and are completely soluble in each other. Differential thermal analysis and X-ray diffraction were used to examine the synthesis and phase constitution. Dielectric properties—dielectric permittivity e and dielectric loss tan δ of ceramic samples of originally s…
Dehydration of detomidine hydrochloride monohydrate
2010
The thermodynamic stability of detomidine hydrochloride monohydrate has been evaluated on the basis of phase transition kinetics in solid state. A method free of empirical models was used for the treatment of kinetic data, and compared to several known solid state kinetic data processing methods. Phase transitions were monitored by powder X-ray diffraction (PXRD) and thermal analysis. Full PXRD profiles were used for determining the phase content instead of single reflex intensity measurements, in order to minimize the influence of particle texture. We compared the applicability of isothermal and nonisothermal methods to our investigation of detomidine hydrochlorine monohydrate dehydration.
Modelling phase transition kinetics of chenodeoxycholic acid with the Runge–Kutta method
2009
Abstract The phase transition kinetics of two chenodeoxycholic acid polymorphic modifications— form I (stable at high temperature), form III (stable at low temperature) and the amorphous phase has been examined under various conditions of temperature and relative humidity. Form III conversion to form I was examined at high temperature conditions and was found to be non-spontaneous, requiring seed crystals for initiation. The formation kinetic model of form I was created incorporating the three-dimensional seed crystal growth, the phase transition rate proportion to the surface area of form I crystals, and the influence of the amorphous phase surface area changes with an empirical stage poin…
Excited state absorption and energy-transfer mechanisms of up-conversion luminescence in Er3+-doped oxyfluoride glass ceramics at different temperatu…
2010
Abstract Oxyfluoride silicate glass SiO2–Al2O3–Na2CO3–NaF–LaF3–ErF3 was synthesized. The glass transition and crystallization temperatures were determined by differential thermal analysis. Glass ceramics containing LaF3:Er3+ crystallites of size ∼20 nm were formed in the glass matrix after the heat treatment of the precursor glass in the vicinity of the crystallization temperature. Up-conversion luminescence, excitation spectra as well as time-resolved up-conversion luminescence of the glass and glass ceramics were studied at different temperatures. The up-conversion transients showed that at room temperature the dominant mechanism of the up-conversion luminescence in the glass ceramics is …
Structural transformations in amorphous selenium as studied by the differential thermal analysis and exoelectron emission technique
2007
The parameters (temperature, activation energy) of the surface and volume glass transition (retrification process) in amorphous selenium produced by rapid quenching of the liquid phase have been determined using the EEE and DTA techniques. EEE is a surface effect connected with structural transformations in the surface layer whereas the DTA measurements give the information about the transformations occurring in the volume of the sample. It has been found that the surface retrification of selenium occurs with activation energy smaller than the volume retrification, both observed in the first heating run. The value of activation energy for the volume retrification measured in the second DTA …
Study of the thermal decomposition of bromazepan complexes with Co(II), Ni(II), Cu(II) and Zn(II)
1984
Abstract The thermal behaviour of complexes of bromazepan with Co(II), Ni(II), Cu(II) and Zn(II) was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The complexes decompose in two steps: dehydration and decomposition. A correlation between the dehydration temperatures of MB2Xn and the coordinating ability of X is observed.
Advances in Anodic Alumina Membranes-based fuel cell: CsH2PO4 pore-filler as proton conductor at room temperature
2009
Abstract Anodic alumina membranes (AAM) filled with cesium hydrogen phosphate proton conductor have been tested as inorganic composite electrolyte for hydrogen–oxygen thin film (≤50 μm) fuel cell (TFFC) working at low temperatures (25 °C), low humidity ( T gas = 25 °C) and low Pt loading (1 mg cm −2 ). Single module TFFC delivering a peak power of around 15–27 mW cm −2 , with open circuit voltage (OCV) of about 0.9 V and short circuit current density in the range 80–160 mA cm −2 have been fabricated. At variance with pure solid acid electrolytes showing reproducibility problems due to the scarce mechanical resistance, the presence of porous alumina support allowed to replicate similar fuel…
Thermal and spectroscopic investigation of europium and samarium sulphates hydrates by TG-FTIR and ICP-MS techniques.
2005
The investigation of europium(III) sulphate hydrate and samarium(III) sulphate hydrate was performed by thermal analysis (TG-DTG) and simultaneous infrared evolved gas analysis-Fourier transformed infrared (EGA-FTIR) spectroscopy. The TG, DTG and DTA curves were recorded at the 25-1400 degrees C in the dynamic air atmosphere by TG/DTA analyser. The infrared evolved gas analysis was obtained on the FTIR spectrometer. Eu(2)(SO(4))(3).nH(2)O (n=3.97) and Sm(2)(SO(4))(3).nH(2)O (n=8.11) were analysed, the dehydration and decomposition steps were investigated and the water content was calculated. The formation of different oxysulphates was studied. The trace rare earth elements in Eu and Sm sulp…