Anisotropic Optical Spectra of YAlO3 (YAP) Single Crystals in the Vacuum Ultraviolet Region. II. Spectra of Reflectivity

Anisotropic reflectivity spectra of YAlO 3 single crystals at 297 K measured with the light polarized parallel to each of the a , b and c axes are presented in the range from ∼6.5 eV to ∼120 eV. A comparison of the reflectivity spectra of YAlO 3 with those of Y 2 O 3 , Y 3 Al 5 O 12 and α-Al 2 O 3 single crystals reaffirms that the peaks at ∼35 eV are mainly associated with the Y 3+ 4 p 6 and the features beyond ∼76 eV with the Al 3+ L 2,3 . Anisotropic reflectivity spectra at 10 K are shown in the region from ∼7 eV to 15 eV. Effective optical dielectric constants calculated by the sum rule including the imaginary part of the dielectric constant up to ∼120 eV are seen to saturate at the values corresponding to 98.0% ∼ 99.7% of the literature values of the optical dielectric constant.