Lattice aluminium compounds

Calculated from the mean square displacement of the lattice atoms measured by X-ray diffraction. Tablett.l-itl Melting point of aluminium compounds... 

The crystallographic requirement for tire formation of G-P zones is that the material within the zones shall have an epitaxial relationship with the maUix, and tlrus the eventual precipitate should have a similar unit cell size in one direction as tha maUix. In dre Al-Cu system, the f.c.c. structure of aluminium has a lattice parameter of 0.4014 nm, and the tetragonal CuAl2 compound has lattice parameters a — 0.4872 and b — 0.6063 nm respectively. 

Our experience has shown that the hydrolysis of aluminium phosphide with cold water is the most suitable method for the laboratory preparation of phosphine. Here it is important that the aluminium phosphide be as pure as possible in order to avoid the formation of spontaneously inflammable phosphine. The presence of small quantities of diphosphine and also higher phosphines are responsible for this spontaneous inflammability 96.276-278) jj. gp, pears, however, that these are only formed when P—P bonds are already present in the phosphide. Accordingly the hydrolysis of aluminium phosphide, prepared from the elements with phosphorus in slight excess, always leads to spontaneously inflammable phosphine. The formation of diphosphine and higher phosphines from aluminium or alkaline earth metal phosphides, which contain excess phosphorus, can be easily understood when the lattices of these compounds are considered. 

Compounds of aluminium and magnesium in the lower oxidation states, A1(I) and Mg (I), do not exist under normal conditions. If we make an assumption that the radius of AF or Mg is the same as that of Na (same row of the Periodic Table), then we can also equate the lattice energies, MCI. Use this information in a Born-Haber cycle to calculate... 

The melting point of titanium is 1670°C, while that of aluminium is 660°C.142 In kelvins, these are 1943 K and 933 K, respectively. Thus, the temperature 625°C (898 K) amounts to 0.46 7melting of titanium and 0.96 melting of aluminium. Hence, at this temperature the aluminium atoms may be expected to be much more mobile in the crystal lattices of the titanium aluminides than the titanium atoms. This appears to be the case even with the Ti3Al intermetallic compound. The duplex structure of the Ti3Al layer in the Ti-TiAl diffusion couple (see Fig. 5.13 in Ref. 66) provides evidence that aluminium is the main diffusant. Otherwise, its microstructure would be homogeneous. This point will be explained in more detail in the next chapter devoted to the consideration of growth kinetics of the same compound layer in various reaction couples of a multiphase binary system. 

The electrical conductivity in the liquid state of the halides, e.g. the chlorides, also provides a well-marked difference between the non-conducting shielded compounds and the good conducting non-shielded compounds with free ions in the melt (Biltz, Klemm)17 . Aluminium chloride here also forms a special case in so far that quite exceptionally the solid substance (coordination lattice) has a higher conductivity than the liquid (molecules A12C16). 

The stabilisation of the zeolites using heat treatment under steam (vapour treatment) causes migration of aluminium out of the lattice. The result is the formation of an amorphous compound that can be detected by XRD in the form of a poorly defined scattering back-... 

The compounds R3MC and RM3C3 are the only known compositions that exist in the rare-earth-metal-(aluminium, gallium, indium and thallium)-carbon systems at the present time. A number of reports on the preparation of cubic perovskite-type carbides containing rare earth elements with the general formula RjMC 00 (Jeitschko et al. 1964, Rosen and Sprang 1965, Haschke et al. 1966a, b, Nowotny 1968) contain little information about their properties other than their lattice parameters. 

Conductive heat transfer has a phononic nature, which means that the heat is transferred due to the oscillation of the atoms in the crystal lattice. Crystals with a simple lattice, such as sihcon carbide or carbon, have a lower dissipation of heat waves and a higher thermal conductivity compared to crystals with a more complex lattice. For example, the conductive thermal conductivity of aluminium nitride or silicon carbide (binary compounds with approximately equal atomic weights) is higher than alumina, magnesia, and zirconia. And the conductive thermal conductivity of said alumina, magnesia, and zirconia is higher than that of spinel, mullite, and zircon. 

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