Structure thermal treatment

Damle et al. observed that the reduction of the Pd(II) ions in the stearic acid-Ag nanocomposite film leads to the formation of a mixture of individual Ag and Pd nanoparticles as well as particles in the Ag-core/Pd-shell structure. Thermal treatment of the stearic acid-(Ag/Pd) nanocomposite film at 100 °C, however, resulted in the formation of an AgPd alloy [142]. 

Dqiending on the final application of a textile scaffold, warp knittii weaving, braiding and non-woven technologies can be used to manufacture the textile structure. Thermal treatment can be iqqilied to adjust the pmoshy, geometry and elasticity of the produced textiles. 

The properties of an alloy (yield strength, toughness, oxidation resistance, etc.) depend critically on its constitution and on two further features of its structure the scale (nm or ym or mm) and shape (round, or rod-like, or plate-like) of the phases, not described by the constitution. The constitution, and the scale and shape of the phases, depend on the thermal treatment that the material has had. 

Other topics recently studied by XPS include the effects of thermal treatment on the morphology and adhesion of the interface between Au and the polymer trimethylcy-clohexane-polycarbonate [2.72] the composition of the surfaces and interfaces of plasma-modified Cu-PTFE and Au-PTFE, and the surface structure and the improvement of adhesion [2.73] the influence of excimer laser irradiation of the polymer on the adhesion of metallic overlayers [2.74] and the behavior of the Co-rich binder phase of WC-Co hard metal and diamond deposition on it [2.75]. 

Organic metal salts retard the development of color in the thermal treatment of PVC, and their ability to react selectively with allylic and tertiary chlorine structures according to Eq. 23 has been demonstrated with model compounds [19,32,113,115]. 

As with most other metal and alloys systems, nickel and certain of its alloys may suffer intergranular corrosion in some circumstances. In practice, intergranular corrosion of nickel alloys is usually confined to the vicinity of welds as a result of the effects produced by the welding operation on the structure of the material in those regions. Alloys that are subjected to other similarly unfavourable thermal treatments may also become susceptible. The compositions of most commercial nickel alloys that are marketed today are. 

The attack of most glasses in water and acid is diffusion controlled and the thickness of the porous layer formed on the glass surface consequently depends on the square root of the time. There is ample evidence that the diffusion of alkali ions and basic oxides is thermally activated, suggesting that diffusion occurs either through small pores or through a compact body. The reacted zone is porous and can be further modified by attack and dissolution, if alkali is still present, or by further polymerisation. Consolidation of the structure generally requires thermal treatment. 

Time-temperature-transformation (T-T-T) diagrams are used to present the structure of steels after isothermal transformation at different temperatures for varying times. The T-T-T diagram for a commercial eutectoid steel is shown in Fig. 20.48a. Also shown on the curves are the points at which the microstructures illustrated in Figs. 20.46 and 20.47 are observed, and the thermal treatments producing these structures. When a steel partially transformed to, say, pearlite, is quenched from point a in Fig. 20.48a to below nif, the untransformed austenite transforms to martensite. 

Since hydrofluoride synthesis is based on thermal treatment at relatively high temperatures, the possibility of obtaining certain fluorotantalates can be predicted according to thermal stability of the compounds. In the case of compounds whose crystal structure is made up of an octahedral complex of ions, the most important parameter is the anion-cation ratio. Therefore, it is very important to take in to account the ionic radius of the second cation in relation to the ionic radius of tantalum. Large cations, are not included in the... 

It is possible, in general, that CoNb2F)2 is present only in the gaseous phase at increased temperatures due to insufficient amounts of ligands that are necessary for the formation of a stable solid compound. Further thermal treatment of Co2Nb03F3 at temperatures of 1000-1100°C leads to the formation of Co4Nb209 crystals with a pseudoilmenite structure. 

Co2Nb03F3 was obtained as a result of the thermal treatment of CoNbOF5, predominantly prepared by the hydrofluoride method [129]. This compound crystallizes in a rutile-type structure that can be achieved due to the statistical distribution of cations within the oxyfluoride octahedrons. 

The phase composition of products obtained from the thermal treatment of LiNbOF4 and NaNbOF4 was investigated using X-ray diffraction and vibration spectroscopy, as reported in [379]. Compounds with the following structures were found M2NbOF5, MNb02F2 and MNbC>3, where M = Li or Na. 

The partially reduced form of niobium accounts for the color change of samples that underwent thermal treatment in vacuum or inert atmospheres. Whereas the thermal treatment of the mixture in air leads to the simultaneous oxidation of Nb4+ by oxygen, this is actually equivalent to the replacement of fluorine ions by oxygen ions in the complex structure of oxyfluoroniobate. Extended thermal treatment of systems containing LiNbOF4 and LiF yields a mixture of LiF and LiNbOs as the final thermal decomposition product. 

An irreversible extinction of the SHG signal at 150-200°C is observed for a number of other fluoride and oxyfluoride compounds of tantalum and niobium that crystallize in centrosymmetric space groups. This phenomenon is especially typical for the compounds prepared by precipitation from solutions [206]. The appearance of the weak SHG signal for such compounds is related to imperfections in their crystal structure and the creation of dipoles. Nevertheless, appropriate thermal treatment improves the structure and leads to the disappearance of dipoles and to the irreversible disappearance of the corresponding SHG signal. 

Many studies on template thermal degradation have been reported on zeolites of industrial interest including ZSM5 [1-5], silicalite [1], and beta [6-8], as well as surfactant-templated mesostructured materials [9-13]. The latter are structurally more sensitive than molecular sieves. Their structure usually shrinks upon thermal treatment. The general practice is slow heating at 1 °C min (N2/air) up to 550 °C, followed by a temperature plateau. 

It is interesting to compare the thermal-treatment effect on the secondary structure of two proteins, namely, bacteriorhodopsin (BR) and photosynthetic reaction centers from Rhodopseudomonas viridis (RC). The investigation was done for three types of samples for each object-solution, LB film, and self-assembled film. Both proteins are membrane ones and are objects of numerous studies, for they play a key role in photosynthesis, providing a light-induced charge transfer through membranes—electrons in the case of RC and protons in the case of BR. 

The present work demonstrates that the mixed oxide catalyst with inhomogeneous nanocrystalline MosOu-type oxide with minor amount of M0O3- and Mo02-type material. Thermal treatment of the catalyst shows a better performance in the formation of the crystals and the catalytic activity. The structural analysis suggests that the catalytic performance of the MoVW- mixed oxide catalyst in the partial oxidation of methanol is related to the formation of the M05O14 t3 e mixed oxide. 

After treatment at 373 K in helium flow, the coordination numbers of Mo-0, Mo-S and Mo-Mo were not largely different from those in the cluster 1 and the distances of Mo-0, Mo-S and Mo-Mo were hardly changed. After treatment at 573 K in He flow, however, the color of NaY changed from brown to black and the curve fitting results of the EXAFS data exhibited lower coordination numbers of all interactions than those of the cluster 1. The decrease in the coordination number seems to be not due to the decrease in sulfur amount in the catalyst but to the disordering of each interaction since the S/Mo ratio hardly decreased after thermal treatment. These results show that the structure of the cluster 1 loaded on NaY was maintained at 373 K, but lost at 573 K. 

This study could be extended to the synthesis of iron nanoparticles. Using Fe[N(SiMe3)2]2 as precursor and a mixture of HDA and oleic acid, spherical nanoparticles are initially formed as in the case of cobalt. However, a thermal treatment at 150 °C in the presence of H2 leads to coalescence of the particles into cubic particles of 7 nm side length. Furthermore, these particles self-organize into cubic super-structures (cubes of cubes Fig. ) [79]. The nanoparticles are very air-sensitive but consist of zerovalent iron as evidenced by Mossbauer spectroscopy. The fact that the spherical particles present at the early stage of the reaction coalesce into rods in the case of cobalt and cubes in the case of iron is attributed to the crystal structure of the metal particles hep for cobalt, bcc for iron. 

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