Refractive index and dispersion of fluorides and oxides

The refractive indices of 509 oxides and 55 fluorides were analyzed using two forms of a one-term Sellmeier equation: (1) 1/(n(2)-1) = -A/lambda(2)+B, where A, the slope of the plot of (n(2)-1)(-1) versus lambda(-2) in units of 10(-16) m(2), gives a measure of dispersion and B, the intercept of the plot at lambda=infinity, gives n(infinity)=(1+1/B)(1/2) and (2) n(2)-1=EdEo/(E-o(2)-((h) over bar omega)(2)), where (h) over bar omega the photon energy, E-o = the average single oscillator (Sellmeier) energy gap, and E-d=the average oscillator strength, which measures the strength of interband optical transitions. Form (1) was used to calculate n at lambda=589.3 nm (n(D)) and n at lambda=infinity (n(infinityproportional to)), and the dispersion constant A. The total mean polarizabilility for each compound was calculated using the Lorenz-Lorentz equation: alpha(e)=3/4pi [(V-m)(n(infinity)(2-)1)/(n(infinity)(2)+2)], where V-m is the molar volume in Angstrom(3). Provided for each compound are: n(D), n(infinity), V-m, <alpha(e)>, <A>, <B>, <E-d>, <E-o>, the literature reference, the method of measurement of n and estimated errors in n. Results obtained by prism, infrared reflectivity, ellipsometry, and interference methods are compared. Consistency of dispersion values among like compounds and structural families is used to evaluate the accuracy of refractive index data. Dispersion values range from 40 to 260x10(-16) m(2) with the majority of values in the range of 60-100x10(-16) m(2). High dispersion is associated with s(2), p(6), d(10), and transition metal ions, H2O, and crystalline hydrates, whereas normal dispersion values are found in borates, aluminates, gallates, silicates, germanates, phosphates, and sulfates not containing H2O or any of the above ions. Exceptionally high dispersion is observed in liquid H2O, Fe2O3,Y3Fe5O12, FeOOH, Fe-2(SO4)(3),UO2,Cu2O, V2O5, MgCrO4.7H(2)O, and Cs2Mg(CrO4)(2).6H(2)O. (C) 2002 American Institute of Physics.