Search results for "Thermal Analysis"

K2AuPS4, TI2AuPS4, K2AuAsS4, and KAu5P2S8: Syntheses, structures, and properties of quaternary gold thiophosphate and thioarsenate compounds

1998

The novel compounds K2AuPS4 (1), Tl2AuPS4 (2), K2AuAsS4 (3), and KAu5P2S8 (4) have been synthesized by direct reaction of the elements with a molten alkaline polythiophosphate(arsenate) flux at 550°C. The crystal structures of these compounds have been determined by single-crystal X-ray diffraction techniques. 1, 2, and 3 crystallize in the monoclinic space group P21/m. The structures of 1, 2, and 3 consist of infinite, one-dimensional anionic chains running along the crystallographic b axis. The chains are separated by potassium or thallium ions. Neighbouring Au atoms are bridged by MS43− tetrahedra (M = P, As) in a trans orientation. Compound 4 crystallizes in the space group P21/c. The a…

From nitrides to carbides: topotactic synthesis of the η-carbides Fe3Mo3C and Co3Mo3C

2004

The molybdenum bimetallic interstitial carbides Fe(3)Mo(3)C and Co(3)Mo(3)C have been synthesized by temperature-programmed reaction (TPR) between the molybdenum bimetallic interstitial nitrides Fe(3)Mo(3)N and Co(3)Mo(3)N and a flowing mixture of CH(4) and H(2) diluted in Ar. These compounds have been characterized by X-ray diffraction, laser Raman spectroscopy, elemental analysis, energy dispersive analysis of X rays, thermal analysis (in air) and scanning electron microscopy (field emission). Their structures have been refined from X-ray powder diffraction data. These carbides crystallize in the cubic system, space group Fd3m[a= 11.11376(6) and 11.0697(3)[Angstrom] for Fe and Co compound…

Hydrothermal Synthesis, Crystal Structure, and Magnetism of Na 2 [Ir(OH) 6 ] and its Dehydration to Na 2 IrO 3

2021

Thermally highly stable amorphous zinc phosphate intermediates during the formation of zinc phosphate hydrate.

2015

The mechanisms by which amorphous intermediates transform into crystalline materials are still poorly understood. Here we attempt to illuminate the formation of an amorphous precursor by investigating the crystallization process of zinc phosphate hydrate. This work shows that amorphous zinc phosphate (AZP) nanoparticles precipitate from aqueous solutions prior to the crystalline hopeite phase at low concentrations and in the absence of additives at room temperature. AZP nanoparticles are thermally stable against crystallization even at 400 °C (resulting in a high temperature AZP), but they crystallize rapidly in the presence of water if the reaction is not interrupted. X-ray powder diffract…

Organobase-Catalyzed Synthesis of Multiarm Star Polylactide With Hyperbranched Poly(ethylene glycol) as the Core

2011

Multiarm star copolymers consisting of the polyether-polyol hyperbranched poly(ethylene glycol) (hbPEG) as core and poly(L-lactide) (PLLA) arms are synthesized via the organobase- catalyzed ring-opening polymerization of lactide using hbPEG as a multifunctional macroinitiator. Star copolymers with high molecular weights up to 792 000 g mol−1 are prepared. Detailed 2D NMR analysis provides evidence for the attachment of the PLLA arms to the core and reveals that the adjustment of the monomer/initiator ratio enables control of the arm length. Size exclusion chromatography measurements show narrow molecular weight distributions. Thermal analysis reveals a lower glass transition temperature, me…

Comparison of two melting range analysis methods with lactitol monohydrate

2001

Abstract In pharmacopoeia, the melting point is determined by a standard method with a melting point instrument. The melting point can also be determined with differential scanning calorimetry (DSC). In this study, the standard method and DSC method are compared for determining the melting range of lactitol monohydrate. The effect of initial temperature, grinding, and drying on the melting range of different lactitol monohydrate samples was studied by a melting point instrument. The melting point and melting enthalpy of the stable form of lactitol monohydrate was identified by DSC. The statistical analysis of the results is based on a t-test. All studied variables had a small effect on the …

Mechanochemical synthesis of an Eu(III) complex. Preparation and Luminescence Properties of PMMA:[C42H38N5O19Eu] Hybrid Films

2015

Abstract Photoluminescent films of poly(methyl methacrylate), PMMA, doped with the complex [EuL2(H2O)2(NO3)3] were prepared, where L is the neutral ligand 2,6-bis[2-formylphenoxymethyl]pyridine (C21H17NO4). The Eu(III) complex was synthesized by classic chemosynthesis, and also through a solvent-free mechanochemical synthesis, and characterized by spectroscopy, thermal analysis (TGA and DTA), and single crystal X-ray diffraction. The mechanochemical route improves the yield for the complex, which is synthesized over times considerably shorter compared to the traditional synthesis, and through a solvent-free procedure. The photoluminescent properties of the Eu(III) complex and hybrid films P…

Cubic and rhombohedral Ba4Lu3F17:Er3+ in transparent glass ceramics: Crystallization and upconversion luminescence

2018

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Carbon Fiber Composites Cured by γ-Radiation-Induced Polymerization of an Epoxy Resin Matrix

2008

The use of ionizing radiation in order to initiate polymerization of suitable monomers has found increased interest in the last two decades due to its several advantages. In this work, carbon fiber composites through gamma radiation polymerization of epoxy matrices have been produced for aerospace and advanced automotive applications. Composite samples were produced by irradiation at room temperature using different radiation doses and, as reference, thermal curing of the same epoxy resin formulations was also carried out. Furthermore, some irradiated samples were subjected to postirradiation thermal curing to complete the polymerization reactions. The properties of the cured materials were…

Phase evolution by thermal treatment of equimolar cobalt–magnesium cordierite glass powders

2004

Abstract The structural evolution with annealing time at temperatures between 900 and 1100 °C of loosely compacted equimolar cobalt–magnesium cordierite glass powder was reported. The glass, with composition MgCoAl4Si5O18, was prepared by melting a glass precursor, previously synthesized by a semiwet method, at 1650 °C. Field emission scanning electron microscopy (FESEM) of isothermally heated glasses at 900 and 950 °C revealed increased phase separation with thermal treatment. X-ray diffraction (XRD) results of these powders indicated that the first crystalline phase formed was μ cobalt-containing cordierite which transformed to α cordierite with longer annealing. At the beginning of the μ…