Refractive index and optical dispersion of In2O3, InBO3 and gahnite

Abstract

Refractive indices of In2O3, In2−xSnxO3, InBO3 and 2 different gahnite crystals (Zn0.95Fe0.05Al2O4 and Zn0.91Mg0.04Mn0.03Fe0.03Al1.99Fe0.01O4) were measured at wavelengths of 435.8–643.8nm and were used to calculate n (nD) at λ=589.3nm and (n∞) at λ=∞ with the one-term Sellmeier equation 1/(n2−1)=−A/λ2+B. Total polarizabilities, αtotal, were calculated from n∞ and the Lorenz–Lorentz equation. Refractive indices, nD and dispersion values, A, are, respectively, 2.093 and 133×10−16m2 for In2O3; 2.0755 and 138×10−16m2 for In2−xSnxO3; 1.7995 and 56×10−16m2 for Zn0.95Fe0.05Al2O4; 1.7940 and 57×10−16m2 for Zn0.91Mg0.04Mn0.03Fe0.03Al1.99Fe0.01O4 and no=1.8782 and ne=1.7756 and 〈63〉×10−16m2 for InBO3. The lack of consistency of the polarizabilities of Zn2+ in ZnO and In3+ in In2O3 with the Zn2+ and In3+ polarizabilities in other Zn- and In-containing compounds is correlated with structural strain and very high dispersion of ZnO and In2O3.