Core and shell structure of ytterbium sesquioxide nanoparticles

Raman spectroscopic investigation of lanthana‐doped neodymium‐yttria transparent ceramics

“…[14] The intensity of Raman bands decreases, which means the symmetry of the crystalline structure is lowered, and similar results have also been reported in Eu 3+ -doped Y 2 O 3 [15] and Yb 3+ -doped Y 2 O 3 [16,17] compounds. Compared to the La 2 O 3 -undoped specimen, it is apparent that each band of (Nd 0.01 La x Y 0.99−x ) 2 O 3 (x = 0.05, 0.10) suffers a red shift due to the weak bond strength of La-O and heavy mass of La 3+ ion, as a consequence of which the phonon energy is slightly reduced.…”

“…The FWHMs of the Raman peaks increase with increase in La 2 O 3 content in (Nd 0.01 Y 0.99 ) 2 O 3 ceramics because of the local disorder in the structure, which is caused by the difference in the ionic radii between La 3+ and Y 3+ ions 14. The intensity of Raman bands decreases, which means the symmetry of the crystalline structure is lowered, and similar results have also been reported in Eu 3+ ‐doped Y 2 O 3 15 and Yb 3+ ‐doped Y 2 O 3 16, 17 compounds. Compared to the La 2 O 3 ‐undoped specimen, it is apparent that each band of (Nd 0.01 La x Y 0.99− x ) 2 O 3 ( x = 0.05, 0.10) suffers a red shift due to the weak bond strength of LaO and heavy mass of La 3+ ion, as a consequence of which the phonon energy is slightly reduced.…”

XRD, IR, and Raman investigations of structural properties of Dy2‐xHox O3 prepared by sol gel procedure

“…To visualize anisotropy of x-ray line broadening due to lattice strain and size, we used the program GFOURIER [25], incorporated in the WINPLOTR suite [26]. Raman bands corresponding to both cubic and monoclinic symmetry were found for 25 nm Yb 2 O 3 nanoparticles [35,36]. Raman spectroscopy For the C-type RE sesquioxides, the irreducible representations for the optical and acoustical modes [27,28] are: Γ op = 4A g (Raman)+ 4E g (Raman)+ 14F g (Raman)+ 5A 2u (inactive)+ 5E u (inactive)+ 16F u (IR) Γ ac = F u On the whole, 22 Raman and 16 IR active modes are predicted.…”

Investigations of anharmonic effects via phonon mode variations in nanocrystalline Dy2O3, Gd2O3 and Y2O3

“…Further, the finite‐size effects in nanocrystals are also expected to modify the anharmonicity and the phonon decay times. It has also been reported that owing to the nanosized particles, the core and shell of the sample may have varying symmetries . It has also been reported that the anharmonic constants related to the peak widths and peak positions are higher in nanocrystals than in the bulk, implying a greater degree of anharmonicity in nanocrystals .…”

“…It has also been reported that owing to the nanosized particles, the core and shell of the sample may have varying symmetries. [2,15,16] It has also been reported that the anharmonic constants related to the peak widths and peak positions are higher in nanocrystals than in the bulk, implying a greater degree of anharmonicity in nanocrystals. [17] Very few experiments have been carried out to investigate the temperature dependence of Raman mode positions and line widths in nanocrystals.…”