Mean electronegativity

Recently Jacobs (84, 85) has proposed another system of structural hydroxyls in zeolites based on the mean electronegativities of zeolite lattices according to Sanderson. It was concluded as well that the Bronsted acidity of zeolites varies continuously with their Si/Al content. Let us compare these two approaches. 

Fig. 12. Dependence of the intrinsic Fermi level, calculated as - (EA + Eel2) where EA is the electron affinity (i.e. the energy of the conduction band edge, which can be obtained from the flat-band potential) and Eg the bandgap, on the mean electronegativity of A and B, (xaXb)112 for semiconductors A B, where Xa< Xb are Pauling electronegativities.

Mean electronegativity valeus, en, according to Pauling calculated from thermodynamic data [136]... 

These types of anionic species may be found only in dilute aqueous solutions at high pH. For the hydroxo-aquo species of mean electronegativity (x) the deprotonation goes on until it equals the mean electronegativity of water (%). ... 

The results shown in Fig. 32 indicate an increase in the chemical shift, d /, with increasing mean electronegativity of the zeoHte framework. However, the significant deviation of the chemical shift of bridging OH groups in zeolite 25HNaA is... 

Fig. 2.34 Van Arkel-Ketelaar diagram indicating the bonding character as a function of electronegativity difference Ax and mean electronegativity (x), also see text.

TABLE 8. Refinement factor R(%), mean electronegativities e 5 ) (eV) atomic sizes r(M) (pm), Mulliken electronegativities (eV), Ewald summation indexes p, Ewald summation parameters K (A ), Madelung energies M (eV), ionicity indexes / (%), minimum interatomic distances Rmin (pm) and Madelung constants Rmin) of the eleven pyrosilicates displayed in figure 8. ( ) Mg values (KBa) = 198 pm, exo (Ba) = 1.81 eV). 

Ichikawa, S. (1989). High-Tc superconductors and weighted harmonic mean electronegativities. J. Phys. Chem. 93, 7302-7304. 

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