Raman spectra of R2O3 (R—rare earth) sesquioxides with C-type bixbyite crystal structure: A comparative study

Abstract

Dielectric and optical properties of epitaxial rare-earth scandate films and their crystallization behavior Appl. Phys. Lett. 88, 262906 (2006) Raman spectra of R 2 O 3 (R-Sc, Er, Y, Ho, Gd, Eu, and Sm) powders with C-type bixbyite crystal structure are measured. With the help of these data and ones, previously published for other oxides from the same structural family, general dependencies of the frequencies of the Raman peaks on the cubic crystal unit cell parameter are constructed. Using these dependencies and knowing the symmetry of the peaks for one of the oxides, determined from previous single-crystal measurements, it is possible to find out the symmetry of the peaks from the spectra of all compounds. It was found that the frequency of the six lowest frequency peaks scales with the square root of the mass of the rare earth showing that mainly R ions take part in these vibrations. These results agree with performed here lattice dynamical calculations. The anomalous softening of the frequency of some peaks in the spectra of Eu 2 O 3 is discussed. V C 2014 AIP Publishing LLC.

Luminescence enhancement by energy transfer in melamine-Y2O3:Tb3+ nanohybrids

“…19 According to the most recent attributions, we identify the F g modes at 468 and 592 cm À1 . 20 Furthermore, adjacent to the most intense contribution, we recognise two not completely resolved vibrations at 329 and 429 cm À1 attributed to F g þ E g and A g modes, respectively. 20 The organic functionalised sample presents new features at 700 and 990 cm À1 that could be attributed to the melamine ( Fig.…”

Stabilization of cubic phase in dense Eu2O3 ceramics

“…A spectrum of a purely cubic Eu 2 O 3 pellet sintered at 1000°C is shown below for comparison. Indeed, the main cubic Raman mode at 339 cm À 1 can be identified, [19,22,23] however, differences are evident. In fact, the spectrum of the green regions perfectly matches the spectrum reported by Lui et al [24] which corresponds to a 52% concentration of small Eu 2 O 3 cubic crystallites on amorphous Al 2 O 3 .…”

The effect of synthesis conditions on the structure of compounds formed in the Dy2O3–TiO2 system

“…4, upon annealing of the precursor Dy 2 O 3 : TiO 2 = 1 : 1.4 in the temperature range of 600-800°C, the 145, 393, 515, and 636 cm -1 modes, which correspond to TiO 2 with the anatase structure [23], appear in the Raman spectra. At 900°C, the Raman spectrum still exhibits a strong mode at 145 cm -1 (a-TiO 2 ) and new modes at 307 cm -1 (pyrochlore type Dy 2 Ti 2 O 7 [22]), 370 cm -1 (cubic Dy 2 O 3 phase [24]), and 441 and 620 cm -1 (rutile type TiO 2 [23]). In this case, the weak mode at 515 cm -1 can be assigned to both a-TiO 2 and pyrochlore type Dy 2 Ti 2 O 7 .…”