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AgCu 1 − x Fe x S compounds were synthesized by partial Cu → Fe replacement in the AgCuS crystal at a concentration range of 0 ≤ x ≤ 0.03. In the differential thermal analysis spectrum obtained at a temperature range of 300 K ≤ T ≤ 1300 K, endoeffect corresponding to the structural phase transition in the AgCuS compound was observed at the temperature T = 938 K. It has been determined that this result is also observed in the AgCu 0. 9 9 Fe 0. 0 1 S compound obtained by partial replacement of Cu atoms by Fe atoms. However, in the compound of AgCu 0. 9 7 Fe 0. 0 3 S this effect was observed at higher temperatures. The thermal capacities and enthalpies of phase transitions were calculated for the given compounds. [ABSTRACT FROM AUTHOR]

The structure and thermal properties of Ba 0. 5 La 0. 5 MnO3 polycrystalline powder have been investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. The structural studies have shown that Ba 0. 5 La 0. 5 MnO3 compound crystallizes in perovskite structure with Pm-3m cubic symmetry group. The lattice parameters were obtained to be a = b = c = 3.9073 Å. Mass changes have been observed from thermogravimetric (TG) and differential thermogravimetric (DTG) curves obtained in a wide temperature interval of 30–950 ∘ C. Free energy and enthalpy changes for all observed transformations were determined. Observed endo and exo effects. [ABSTRACT FROM AUTHOR]

As ammonium dihydrogen phosphate (ADP) is a popular nonlinear optical crystal, to engineer its linear and nonlinear optical properties, the chalcogenide compound cobalt sulphide (CoS) was doped and the crystals were grown by the slow solvent evaporation method. To increase the solubility of CoS in water, its nanoparticles were synthesized by wet chemical technique using ethylene diamine as the capping agent followed by microwave irradiation. The nanoparticle sample exhibited finite solubility in water and was used to dope in ADP crystals. The powder XRD patterns showed the single phase nature of the doped crystals. The FTIR spectra confirmed the presence of various functional groups and EDAX gave the estimation of Co and S elements. The EPR spectroscopy also confirmed the presence of cobalt in the doped samples. TGA indicated slightly less thermal stability of the doped crystals compared to the pure ADP. The dielectric study was carried out at room temperature in the frequency range from 100Hz to 1MHz. Also, various linear optical parameters were evaluated for pure and doped crystals using UV-Vis spectroscopy. The second harmonic generation (SHG) efficiency of Nd:YAG laser was evaluated by the Kurtz and Parry method for the doped samples, it was found to be slightly lesser than that of the pure ADP crystals. [ABSTRACT FROM AUTHOR]

We have investigated the elastic, cohesive and thermal properties of (Lu, Sc) VO3 and Sc1-𝓍Lu𝓍VO3(0.6 ≤ 𝓍 ≤ 0.9) perovskites by means of a modified rigid ion model (MRIM). The variation of specific heat is determined following the temperature driven structural phase transitions. Also, the effect of lattice distortions on the elastic and thermal properties of the present pure and doped vanadates has been studied by an atomistic approach. The calculated bulk modulus (BT), reststrahlen frequency (ν0), cohesive energy (ϕ), Debye temperature (θD) and Gruneisen parameter (γ) reproduce well with the corresponding experimental data. The specific heat results can further be improved by including the magnetic ordering contributions to the specific heat. [ABSTRACT FROM AUTHOR]

Polycrystalline garnet ferrites Dy3-xNix Fe5O12, where (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) have been prepared by the standard ceramic technique and their crystalline structure were identified by X-ray diffraction and IR spectroscopy. The differential thermal analysis (DTA) reveals two peaks. It is observed that an endothermic peak between 587 and 498 K for all samples which is due to the magnetic phase change from ferrimagnetic to paramagnetic state. The exothermic peak at about 700 K may be attributed to the crystallization of Dy3-x NixFe5O12 with garnet structure. DC electrical resistivity, thermoelectric power, charge carrier concentration and charge carrier mobility have been studied at different temperatures: It was found that the DC electrical conductivity increases linearly with increasing temperature ensuring the semiconducting nature of samples. The values of the thermoelectric power were negative for samples of 0.0 < x < 0.4 indicating that the majority of the charge carrier are electrons in these samples while it was positive for sample of x = 0.5 at room temperature, and negative at high temperature. Using the values of the DC electrical conductivity and thermoelectric power, the values of the charge carrier concentration and the charge carrier mobility were calculated. Finally thermal properties have been studied. [ABSTRACT FROM AUTHOR]

The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) with aromatic diamide-diimide-diamines having aryl ether, sulfone and methylene linkages was studied by differential scanning calorimetry (DSC). Nine diamide-diimide-diamines of varying structure were synthesized by reacting 1 mole of dianhydride with 2 moles of L-cysteine (S) in a mixture of acetic acid and pyridine (3:2 V/V) followed by activation with thionyl chloride (SOCl2) and then condensation with excess of diamines. Structural characterization of diamide-diimide-diamines was done by using FTIR, 1H-NMR, 13C-NMR spectroscopy and elemental analysis. The peak exotherm temperature (TP) was lowest in DGEBA cured using EPSM and highest in DGEBA cured using ENSS. Thermal stability of the isothermally cured DGEBA with diamide-diimide-diamines was investigated using dynamic thermogravimetry (TGA) in nitrogen atmosphere, and it was found that NTDA based diamide-diimide-diamines provided good stability to DGEBA. The char yield was highest for resin cured with ENSE which might be due to the presence of more compact structure i.e. naphthalene. [ABSTRACT FROM AUTHOR]

A novel intumnescent flame melamine salt of dipentaerythriol phosphate (MDP), was prepared from dipentaerythritol (DPE) polyphosphoric acid, and melamine. The flammability, combustion behavior, and thermal degradation and stability of PP-MDP were characterized. When MDP loading was 20 wt%, LOI values of the composites reached up to 27%, and UL94 rating, V-2. PP-MDP containing 1 wt%; Cu-ZSM-5 presented the highest LOI value of 30.5%; and UL94 rating, V-0, and released lest heat during cone test. TG data showed that the thermal degradation of PP was improved by the addition of MDP. While the loading of ZSM-5 was 1 wt%; or higher, the main weight loss delayed with 50°C, and 80°C, compared with PP and PP-MDP respectively. The appropriate loading Cu-ZSM-5 made PP-MDP possess higher thermal oxidative stability. By SEM, the formation of a dense and thick char layer was observed on the char layer of PP-MDP-containing Cu-ZSM-5, responsible for high flame retardancy. So, the synergistic flame retardancy effects of MDP and Cu-ZSM-5 on PP existed. The mechanism of synergistic effect of Cu-ZSM-5 zeolite on flame retarded PP by MDP was discussed. [ABSTRACT FROM AUTHOR]

Computational simulations on the thermal analysis of metal matrix composite (MMC) composed of Al and SiC were performed in extended areas of SiC volume fraction. Due to the experimental limitations, only the narrow range of SiC volume fraction has been examined. Through the simulation, which enables current experimental situation to extend, we attempted to explore the dependencies of thermal and mechanical properties on changing the value of volume fraction (Vf). To calculate the coefficient of thermal expansion (CTE), variables with temperature and Vf were given in a range from 25°C to 100°C and 0 to 100%, respectively. We obtained quantitative results including CTE as a function of Vf, which are in a good agreement with previous experimental reports. Furthermore, the stress analysis about thermally expanded MMC was performed. At low volume fraction of SiC, the thermal expansion caused the tensile stress at Al near the interface. However, as the volume fraction of SiC was increased, the stress turned to be compressive, it's because the linked SiC particles contracted the expansion of Al. The MMC of Al matrix face centered cubic site SiC particles has more stress evolutions than the MMC of Al matrix simple cubic site SiC particles at same volume fraction. [ABSTRACT FROM AUTHOR]

Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied. ABS/MWNTs composites were prepared via melt blending with the MWNTs content varied from 0.2% to 4.0% by mass. Thermogravimetry results showed that the addition of MWNTs accelerated the degradation of ABS during the whole process under air atmosphere, and both onset and maximum degradation temperature were lower than those of pure ABS. The destabilization effect of MWNTs on the thermal stability of the composites became unobvious under nitrogen, and the addition of MWNTs could improve the maximum degradation temperature. The heat release rate and time of ignition (tign) for the composites reduced greatly with the addition of MWNTs especially when the concentration of nanotubes was higher than 1.0%. The accumulation of carbon nanotubes with a network structure was observed and the char layer became thicker with increasing nanotubes concentration. Results from Raman spectra showed a higher degree of graphitization for the residues of ABS/MWNTs composites. [ABSTRACT FROM AUTHOR]