Structure of Melts

In the highest-temperature (cubic) polymorph, both cations and anions statistically rotate and have quasi-spherical symmetry. Increases of the crystal symmetry before fusion can be seen as a preparation of anisotropic crystals to the transition into isotropic liquid state. 

It is necessary to notice that determining N is the most difficult problem for the XRD study of melts since it depends on a number of assumptions and even conventions, hence the reported values vary widely. For example, in the case of mercury, N derived from the area of the peak corresponding to the interatomic distance, is 14.6, whereas other approaches can give half this value. Gaboon [69] proposed to estimate iV in liquids from the geometrical relations between N and the packing density of atoms, 

As we can see, there is a qualitative agreement between the traditional definition of N from the radial distribution curves and the new volumetric values, but in most cases the latter correspond better to stmctural changes in solids at their transitions to the liquid state. This table shows also that the coordination of atoms in the stractures of metals at fusion, as a rule, varies slightly. Exceptions are the elements which have molecular or heterodesmic structures (Ga, Sb, Bi) in which on fusion the directed bonds are broken, packing becomes more dense and increases, that leads to an increase of the solid s density at fusion. 

In liquid metals under pressure, as in solids, the coordination numbers tend to increase. Thus, in melted iron N = 10.8 at normal pressure and T = 1830 K, 

Evidently, the minimum sizes of atoms correspond to the cation radii, i.e. the structure of a liquid metal really corresponds to a system of cations surrounded by electron clouds. In the case of tellurium the first maximum corresponds to the isolated electronic pair, and the second one to bonded electrons. Tao [79] showed that the atomic diameter in liquid melts near their melting points is close to the covalent diameter multiplied by 0.92. 

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Acid-Base (Lux-Flood) Character of Dissolved Oxide and Its Bearing on Structure of Melt... 

STRUCTURE OF MELTS CONTAINING METALS OF VARIOUS VALENCE... 

To get some information on the structure of melts in the ternary systems, it is very important to define the course of surface tension in the ideal solutions. The general approach used for the variation of surface tension with composition was given by Guggenheim (1977), who stated that the surface tension of ideal solutions should follow the simple additivity formula with a good approximation. The excess surface tension in real systems could be described by the Redlich and Kister (1948) excess function. For the surface tension of real ternary systems it can then be written... 

Kozyavkin, S.A., Lyubchenko, Y.L., 1984. The nonequilibrium character of DNA melting effects of heating rate on the fine structure of melting curves. Nucl. Acids Res. 12 4339-4349. 

Kushiro, I. (1976) Changes in Viscosity and Structure of Melts of NaAlSi206 Composition at High Pressures, J. Geophys. Res. 73, 619-634. 

The surface structure of melt-mixed blends of bisphenol A polycarbonate and PETP was investigated by FTIR attenuated total reflectance spectroscopy. Based on the peak intensity of the aromatic carbonate band for polycarbonate and the aliphatic ester band for PETP by using germanium and KRS-5 ATR crystals, the enrichment of the PETP component in the surface layer of the polycarbonate/PETP blend films was observed. 27 refs. 

DOV] Magnetic susceptibility measurements of melts Electron structure of melts... 

The crystal structure of melt spun iPP is most often the a-monoclinic form [2]. However, if the fiber is quenched rapidly or the stress in the... 

Chrenkova, M., Danek, V., and Silny, A (1996) Structure of melts of tiie system KCI-KBF4-KiTaF , EUCHEM Conference on Molten Salts. Smolenice. Slovakia, A-21. 

Tracz, A., Ungar, G., AFM study of lamellar structure of melt-ciystallized n-alkane C390H782, Macromolecules 2005, 38 4962-4965. 

The appearance in melts of structures with higher CNs should undoubtedly cause a jump increase in heat capacity because of the increase in the number of vibrations. The structure of melts is likely indeed complex and contains separate structural units with different cation CNs. This is difficult to prove on the basis of Raman spectra because of the closeness of vibrational frequencies and low spectral resolution. The vi(Aig) frequency observed for ScCls-CsCl mixtures (Zissi and Papatheodorou, 2002) (see above) is actually an example of successful recording imder the conditions of a low doublet resolution. The high- and low-frequency shoulders were assigned to different structural units thanks to noticeable changes in their concentrations as experimental conditions were varied. 

Solid-State Structure of Melt-Crystallized P(3HB-c< -3HH) Films... 

What are the main processing parameters that affect the structure of melt-spim fibers ... 

The structure of melt-blown fibers can be controlled by varying flow rates of polymer melt and air, temperatures of polymer melt and air, nozzle geometry, and intrinsic properties of polymer melt. For example, higher air flow rate can... 

In addition to the original literature, the reader can find more specialized information in a limited number of review articles. The most comprehensive of these are the volumes Fused Salts, edited by Sundheim (1964), and Molten Salt Chemistry, edited by Blander (1964). The physicochemical literature on fused salts has been reviewed by Blomgren and Van Artsdalen (1960), the electrochemical properties and the structure of melts by Bloom and Bockris (1959), and the detailed conductance, transport, and cryoscopic properties of molten salts by Janz and co-workers (1958). The book Electrochemistry of Fused Salts by Delimarskii and Markov (1961) also includes in the English translation much of the Russian work in this field. Finally, EUis (1960) and Sundheim (1962)... 

Positron annihilation has been proven to be an effective tool to probe the interfacial characteristics of polymer nanocomposites. Zhang et al. used positron annihilation to study structures of melt-compounded HDPE/CaCOj nano-compositites in which nano-CaCOs fillers were treated with a coupling agent. A rapid decrease of free-volume concentration with increasing nano-CaCOs weight fraction was observed. An interfacial layer between the nano-CaCOs fillers and HDPE was also detected, which verified that die interactions between the nano-CaCOs and HDPE matrix indeed restricted the chain segmental motion and reduced the mobilization of polyethylene chains. 

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