Semiempirical correlation between the optical band gap of oxides and hydroxides and the electronegativity of their constituents

摘要

On the basis of new experimental results a previous proposed correlation between the optical band gap of oxides and the difference of electronegativity of their constituents is extended to mixed crystalline and amorphous TiO{sub}2-Fe{sub}2O{sub}3 (d,d-metal oxides) as well as to amorphous passive films grown on Al-Ta, Al-Ti, Al-Nb and Al-W alloys (sp,d-metal oxides). Moreover in analogy with previous results on anhydrous oxides, a correlation is proposed between the optical band gap of hydroxides and the electronegativities of their constituents after substituting the electronegativity of hydroxilic group to that of the oxygen. Like in the case of anhydrous oxides, two different interpolation lines have been found for sp-metal and d-metal hydroxides, respectively.