Optical phonons öf terbium-, dysprosium-,and ytterbium-garnet

Abstract

A comparison is made of the phonon spectra of several rare earth aluminum garnet crystals. The conclusion drawn is that the Raman Spectra with shifts >400 em -1 can be interpreted in terms of motions associated with A104-tetrahedrons of symmetry S 4. Phonon modes associated with the movements of the rare earth ions could also be assigned and the frequency dependence of these modes could be correlated to the apparent change in environment of the rare earth ions in the aluminum garnet crystals when the radii of the ions decrease.

Pressure evolution of the phonon modes and force constants of Tb3Al5O12 and Lu3Al5O12

“…2 it is evident that the force constants show an almost linear dependence upon pressure or relative volume decrease (top x-axis in Fig. 2) and it is similar to that already found for other members of the RE-aluminum garnets, for example Dy 3 [5].…”

“…The goal of the present study is to compare the experimentally obtained pressure slopes for Tb 3 Fig. 1.…”

“…Introduction Rare earth aluminum garnets, such as Tb 3 O 12 , are important optical materials with a wide range of applications like laser host materials, optical lenses and thermal barrier coatings [1]. These compounds crystallize in the cubic structure (space group 10 h O ) consisting of interconnected and slightly distorted octahedra, tetrahedra and dodecahedra having shared oxygen atoms [2].…”

Lattice Dynamical Properties of the Rare Earth Aluminum Garnets (RE3Al5O12)

“…In contrast, Tarte [10] assigned the high frequency bands to modes of the tetrahedral units whereas Hurell et al [11] stated that these bands correspond to molecular modes, but they were not able to decide with certainty whether these are modes of the octahedral or of the tetrahedral units. A complete symmetry assignment of the phonon modes is not unambiguously done up to date although the IR and Raman spectra, for most of the members of the garnet family, have been already published in the literature [9][10][11][12][13][14]. To our opinion, this uncertainty occurs to a larger degree in the accidental degeneracies and/or in the low Raman scattering efficiencies of some modes with different symmetry (see later on in text) and to a lesser degree in the presence of electronic Raman scattering in these materials.…”

Raman Spectra of Hexagonal Ethylsulfates of Yttrium and of some Rare Earths

“…and Nd-E.S. comparable magnitude and spectral lines be-immersed in superfluid helium at 2 K. A descriptween phonon or electronic levels have thus tion of this second type of cryostat will be given similar appearance (1). Information about the elsewhere.…”