Characterization of ytterbium-yttrium mixed oxides using Raman spectroscopy and x-ray powder diffraction

Abstract

Ytterbium-yttrium mixed oxides, which are potential emitter materials for thermophotovoltaic energy converters, were prepared using two different synthesis methods. The results of a characterization using Raman spectroscopy and x-ray powder diffraction (XRD) are presented. The purpose of this study was to confirm whether the materials prepared are indeed substitutional solid solutions of ytterbium oxide and yttrium oxide. Both XRD and Raman spectroscopy are established techniques for the analysis of solid solutions. Linear relationships between the Raman band position and the composition of mixed crystals are known for solid solutions with one active Raman mode. An aspect of this study was the investigation of the relationship between composition and band position and linewidth of vibrational modes when applying Raman techniques to a system with several vibrational modes. A linear relationship between the band position of a vibrational mode at about 600 cm −1 , which is assigned to a stretching vibration, and the ytterbium content of the material was observed. Using an empirical fit to the most intense band around 370 cm −1 , even a substitution of 2 mol% Yb may be detected using non-linear least-squares data analysis. In addition, a discussion of additional features observed in the Raman spectra at Raman shifts >650 cm −1 is presented.

Core and shell structure of ytterbium sesquioxide nanoparticles

“…360 cm −1 is asymmetric and can be decomposed in nine components. We observed more than 15 peaks in the nano sample, while only five bands have been noticed in the study of the bulk Yb 2 O 3 [9,10], (see, Table 2). Another study of Raman spectrum on cc.…”

“…of the rare-earth atom is increasing [9]. An inspection of the ICSD crystal structure database [8] shows that with decreasing rareearth ionic radius the octahedral distortion increases.…”

Optimization of photoluminescence of Y2O3:Eu and Gd2O3:Eu phosphors synthesized by thermolysis of 2,4-pentanedione complexes

“…It should be noted that band broadening is intrinsic to many nanophased oxides, as both small particle size and defects (substitution vacancies) hinder regular phonon propagation and hence induce Brillouin zone folding which makes all phonons Raman active [19][20][21][22][23]. Additionally, inspection of the literature data indicates that in the rare earth sesquioxides Raman band broadening increases as the ionic radius of the rare earth atom is increasing [24]. Accordingly, results for FWHM in Eu 2 O 3 and Eu substituted Gd 2 O 3 are consequences of both the nanophase character of the samples and partial cation substitution.…”

Monoclinic to hexagonal phase transition and hydroxyl motion in calcium-lead hydroxyapatites studied by Raman spectroscopy

“…Moreover the different thermal history of synthesis methods may give materials with different morphologies. 36 The nature of the phase transition in the apatite structure is of great importance for a better understanding of physical and chemical properties related to the configurations of the OH ions and other entities. To obtain more information about structural changes in calcium-lead hydroxyapatite compounds, a complete study of Ca 10 x Pb x (PO 4 ) 6 (OH) 2 (x D 0-10) was undertaken, and preliminary results show drastic modifications when x varies between 4 and 7 6 (A. Hadrich and A. Lautié, to be published).…”