Thermogravimetric analysis metal oxides

The smaller diameter carbon nanotubes are known to be less stable than their larger diameter counterparts and tend to oxidize at lower temperatures. Amorphous carbon and carbon nanotubes with defects undergo combustion at lower temperatures, in Figure 4, we show the thermogravimetric analysis (TGA) curves of undoped as well as N- and B-doped DWNTs. The decomposition temperatures of all these doped DWNTs are comparable to but slightly lower that the decomposition temperature of pure DWNTs. Derivative TGA curves also shows the same trend. The slight increase in mass at high temperature may be due to the small metallic impurity. 

The superconducting oxides La gSr 2Cu04 and I YCujOy were prepared by decomposition of mixed metal nitrates. Thermogravimetric analysis and electron spin resonance measurements indicated the presence of Cu(I) and Cu(III) in the Lai.8Sr.2 u 4 phase. The compound I YC C prepared from the nitrates and subjected to an oxygen anneal at 425°C gave a sharp superconducting transition at 92 K. The phase was stoichiometric but readily decomposed when kept in contact with moist air. 

A Perkin-Elmer TGA-7 instrument calibrated by Curie points of several metal standards has been employed for non-isothermal thermogravimetric analysis. The measurements were carried out at a desired heating rate (in the range of 3 - 40 K/min) in both inert (argon) and oxidizing (oxygen) atmospheres, as appropriate. 

The thermogravimetric analysis (TGA) provides information especially on the content of metallic catalyst particles in the sample. When performed in air, the carbon species will be oxidized to give volatile gaseous products way below 1000 C, whereas the metal portion is-in parts or completely-transformed into its oxides and remains in the crucible as such. Analyzing this residue thus allows for quite an accurate assay of the metal in a nanotube sample. It may be up to 30% (m/m) depending on the quality of the material under test. The portion of amorphous carbon, on the other hand, can only be insufficiently determined by TGA. 

Reliance on mass balance calculations requires extensive knowledge of precursor physical properties. Many transition metal oxide precursors are hydrated salts with variable molecules of water incorporated in their crystal structure, such as ammonium metatungstate ((NH4)gH2W,204oXH20). The amount of hydrated water (x) varies, depending on the manufacturer and atmospheric moisture thermogravimetric analysis should be performed to quantify the water content of the metal salt hydrates for accurate calculations of surface oxide content. 

Thermogravimetric analysis (TGA) can be used to measure mass changes during heating and aging at a certain temperature. Thus TGA is used to study the corrosion resistance of metals and alloys. TGA can also compare the anti-oxidant ability of metals or alloys in different concentrations of various media. The measuring method is... 

The main focus of the project was the elucidation of particle-stabilizer-solvent interactions as a function of the binding strength, the chain length, the concentration of the stabilizers, the polarity of the solvents, and the surface configuration as well as the size and morphology of the metal oxide nanoparticles. Therefore, to characterize the stabilization kinetics, a number of analytical methods, such as thermogravimetric analysis, isothermal titration calorimetry, and spectroscopic methods, were combined. 

During thermal debinding, the feedstocks are heated until the binder is removed via thermal decomposition. Hence, it is important to study the thermal decomposition of the binder in the presence of the powder. The TGA (thermogravimetric analysis) is usually used for this study. The samples would be heated at programmed heating rate with a stream of nitrogen gas purging the furnace s interior to reduce oxidation of the metal powder in the feedstocks. 

Thermogravimetric analysis (25-100°) shows a <0.05% weight loss, indicating that Tl4(C03)[Pt(CN)4] is anhydrous. Emission spectrographic analysis indicates the product to be of high purity it contains the metals Tl and Pt and impurities as follows faint traces of Ca and Li (<0.001%). Iodine-thiosulfate titration studies are negative, indicating no partial oxidation of Pt therefore, Pt is present as Pt °. 

Thermogravimetric and Differential Thermal Analysis has been performed on Cat D. The TG and DTA profiles in Fig 2 show three different steps. The first one is the evaporation of hydrocarbons up to 200 °C with a moderate endotherm. The second step is the oxidation reaction of metal sulfides to oxides (most of the Mo sulfide, and part of the Co sulfide), starting around 200-250 °C. The third step around 350-450 °C is strongly exothermic, due to carbon burn-off as well as the remaining of sulfides oxidation. The carbon bum-off reaction finishes around 500 °C in this experiment performed on a dynamic mode at the heating-up rate of 5 °C/min. 

First, the authors stated that the reduced catalyst surface contained only zero-valent iron. This is based on the analysis of the raw data from the Fe 2p 3/2 spectra. It has been found, however, that it is impossible to identify small levels of oxidized iron in the presence of a large fraction of metallic iron. This is due to the wide distribution of intensity for iron compounds caused by their satellite structure. It is therefore believed that the catalyst described in Ref. 19 contained a similar fraction of iron oxide to the present samples activated with the dry method (see Fig. 2.40). This is in line with the expectation that the presence of the spinel-forming aluminum oxide prevents complete reduction. It should be pointed out that Mossbauer spectroscopy, thermogravimetric reduction, and energy dispersive X-ray analysis all showed a small fraction of oxidized iron to be present within the bulk of fully reduced samples. 

Temperature programmed oxidation (TPO) tests were also performed for the two series of catalysts and their respective supports by registering the sample weight during the thermal process. The analysis of those curves not only allowed accurate determination of the metal loading in the samples (Table 12.1), but also provided some structural information related to the ability of the Pt surface to catalyze the oxidation of the carbon at its periphery. The differential thermogravimetric (DTG) profiles obtained (Figure 12.18) show how the presence... 

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