Abstract
The infrared (IR) reflectance spectra of Gd 3Al 5O 12, Tb 3Al 5O 12 and Lu 3Al 5O 12 single crystals are studied for the first time. At room temperature, 15 infrared active modes for Lu 3Al 5O 12 and 14 for Gd 3Al 5O 12, Tb 3Al 5O 12, out of the 17 theoretically predicted, have been experimentally recorded. The complex dielectric function the refractive index, the absorption coefficient as well as the longitudinal ( ω LO) and transverse ( ω TO) frequencies of the long-wavelength T 1u modes are determined by the Kramers-Kronig transformation of the reflectance spectra. The experimental data are compared and discussed with the theoretical results obtained by the rigid ion model. Our theoretical analysis reveals that the bonds in the tetrahedra exhibit a covalent character while those in the dodecahedra almost ionic character, which is in accordance with the results for other materials of this crystal family.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
