Phonons in Rare-Earth Aluminum Garnets and Their Relation to Lattice Vibration of AlO4

Papagelis, K.; Kanellis, G.; Arvanitidis, J.; Kourouklis, G. A.; Ves, S.

doi:10.1002/(sici)1521-3951(199909)215:1<193::aid-pssb193>3.0.co;2-g

Cited by 17 publications

(13 citation statements)

References 7 publications

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“…These results partially support our former estimates [9], mainly the one corresponding to the quadrupolar-like mode. These results partially support our former estimates [9], mainly the one corresponding to the quadrupolar-like mode.…”

Section: Resultssupporting

confidence: 88%

Phonon Modes in Yb3Al5O12: Pressure Dependence and Model Calculations

Papagelis

Kanellis

Arvanitidis

et al. 2001

phys. stat. sol. (b)

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Section: Resultssupporting

confidence: 88%

Phonon Modes in Yb3Al5O12: Pressure Dependence and Model Calculations

Papagelis

Kanellis

Arvanitidis

et al. 2001

phys. stat. sol. (b)

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“…The relatively high frequency of this mode is originating from the significant stretching of the tetrahedral and octahedral bonds. This eigenvector is the same to the ones obtained in our previous work using symmetry arguments [25].…”

Section: Resultsmentioning

confidence: 93%

“…In a previous study we have shown, in the framework of the site group analysis, that the three A 1g lattice modes are directly connected with the AlO 4 internal vibrations [25]. In particular, the higher frequency A 1g mode ($780 cm --1 ) corresponds to the breathing mode of the free AlO 4 molecular unit and the intermediate frequency A 1g mode ($560 cm --1 ) to the quadrupolar-like mode containing a small breathing component.…”

Section: Resultsmentioning

confidence: 98%

“…Based on this assumption we can postulate that the three frequency regions observed in the Raman spectrum of the RE 3 Al 5 O 12 compounds can be attributed to the splitting (due to the crystal field) of certain molecular modes of the AlO 4 molecular unit [23]. Indeed, site group analysis [24,25], based on the existence of isolated AlO 4 units in the structure of RE 3 Al 5 O 12 , shows that the high frequency region results from the splitting of the n 1 (breathing mode) and n 4 molecular modes of the AlO 4 , the middle frequency region results from the n 2 (quadrupolar) molecular mode splitting while the low frequency region is due to the splitting of (i) translational motion of the rare earth ions, (ii) rotational and translational motion of the AlO 4 units, and (iii) the n 3 molecular mode of the AlO 4 .…”

Section: Resultsmentioning

confidence: 99%

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

Papagelis

Kanellis

Ves

et al. 2002

phys. stat. sol. (b)

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PACS: 63.20.Dj; 78.30.Am; 87.64.Je This paper reports detailed lattice dynamics studies involving experimental Raman scattering measurements and theoretical rigid ion model calculations of the rare earth aluminum garnets (RE 3 Al 5 O 12 ). The studies are fairly involved as these garnets have complex crystal structure with 80 atoms/primitive cell. Our calculations have provided a theoretical understanding of the mode eigenvectors, phonon dispersion relations, density of states, and effective charges of these materials. The calculated Raman mode eigenvectors reveal that they correspond to mixtures of molecular modes of the basic polyhedra, implying thus strongly coupled polyhedra. The assignment of the Raman and infrared active modes has been elucidated and the frequencies of some modes, which do not appear in the vibrational spectrum, have been calculated. Our calculations show a differentiation of the effective charges at the various symmetry sites, which leads to a mostly covalent and to an almost ionic character for the tetrahedral Al-O and the dodecahedral RE-O bonds, respectively. Finally, the dispersion curves along the [100] direction of the Brillouin zone as well as the one and two-phonon density of states have been calculated and discussed.

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“…In the past, the association of the IR and Raman bands of the garnet compounds with certain atomic motions has been documented only by the results of factor group analysis in which the tetrahedral AlO 4 units were treated as isolated entities. [15][16][17] Recently, we have studied extensively the lattice dynamics of various rare earth aluminum garnets with the rigid ion model. 14 Concerning the Raman eigenvectors, our theoretical calculations reveal 14 that the majority of the Raman modes are not related solely to vibrations of certain molecular units of the RE 3 Al 5 O 12 compounds but rather to a linear combination of them.…”

Section: Introductionmentioning

confidence: 99%

Vibrational properties of the rare earth aluminum garnets

Papagelis

Ves

2003

Journal of Applied Physics

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In this work we present single crystal infrared ͑IR͒ reflectance spectra for the Dy 3 Al 5 O 12 and Er 3 Al 5 O 12 compounds, their corresponding optical constants, as well as a discussion concerning the vibrational, dielectric, and elastic properties of various members of the rare earth aluminum garnet family. In the framework of the rigid ion model, the frequencies of the experimentally unresolved infrared active modes, the IR eigenvectors and the partial phonon density of states have been calculated. The role of the different atomic species in the various regions of the IR vibrational spectrum has been elucidated. In particular, it is found that the rare earth ionic mass plays a crucial role in the low frequency IR modes ͑Ͻ200 cm Ϫ1 ͒, while the high frequency modes are related mainly to the molecular modes of the AlO 4 tetrahedral subunit. From the volume dependence of the IR active mode frequencies, their mode Grüneisen parameters are estimated and discussed. Finally, by using a modification of the semiempirical Brout's formula, the bulk moduli have been determined and are compared to those derived from interatomic potential calculations.

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Phonons in Rare-Earth Aluminum Garnets and Their Relation to Lattice Vibration of AlO4

Cited by 17 publications

References 7 publications

Phonon Modes in Yb3Al5O12: Pressure Dependence and Model Calculations

Phonon Modes in Yb3Al5O12: Pressure Dependence and Model Calculations

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

Vibrational properties of the rare earth aluminum garnets

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