Structural and optical properties of nanoparticulate Y2O3:Eu2O3

Abstract

Nanoparticulate Y2 O3 :Eu2 O3 with a small, uniform particle size and a well-defined composition was synthesized using a low temperature microwave plasma process. The structural evolution and the luminescence properties were studied in different states of annealing and Eu2 O3 addition using X-ray diffraction, transmission electron microscopy, and UV-photoluminescence spectroscopy. As synthesized, the samples were amorphous and showed only weak luminescence. Subsequent annealing steps from 500°C to 800°C lead to the formation and growth of cubic Y2 O3 :Eu2 O3 nanocrystals (5–20 nm) and a concomitant strong increase of the luminescence yield already at small grain sizes in the range of 10 nm. No self-quenching effects were observed up to 11 mol% Eu2 O3 .

Annealing temperature effect on structural properties of tin oxide nanoparticles

“…In the basic medium (> pH 7) the OH− ions interact with positively charged Sn2+ and form SnO2. In the present work at higher pH (10,12) hydrolysis and condensation process will be uncontrollable [40] and hence the samples A3 and A4 give irregular shape; subsequently in the Experiment 2 high annealing temperature (Ta = 600 and 800 °C) formed more agglomerated structures. Thus, the FESEM images clearly show that the SnO2-t nanoparticles prepared from pH 8 and on annealing at 400 °C yielded agglomerated spherical shaped nanoparticles (A2 = B2).…”

“…2a, b respectively. Morphology of the tin oxide synthesized from sol-gel method strongly depends on the amount of H+ or OH− ions in the solution [40]. Tin oxide synthesized from the solution pH 6 and Ta 400 °C, contains slurry like morphology with no definite shape (A1).…”

“…However, when pH is increased, changes in the OH− ions concentration occur and decrease the density of H+ ions than that at lower pH. Thus, on increasing the solution pH from acidic to basic the concentration of H+ ions decrease and increase in the OH− ions influences to form the desired structures [40]. In the basic medium (> pH 7) the OH− ions interact with positively charged Sn2+ and form SnO2.…”

Numerical investigation of heat transfer augmentation in curved channel using hybrid nanofluids

“…Masuda et al [3] and Choi et al [4] were the first raised the idea of using nanofluids. Bergman [5] investigated the effects of increasing thermal conductivity and reducing the specific heat of the nanofluid relative to the base fluid and quantified heat transfer enhancement. They show that use of nanofluid instead of pure liquids can either enhance or degrade thermal performance.…”