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Optical and emission Spectroscopy and radiation shielding properties of Sm3+-Doped P2O5 + BaO + La2O3 glasses
(2026-01-01)
Kesavulu, C. R.
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Masthanaiah, E.
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Basavapoornima, Ch
;
Depuru, Shobha Rani
;
Pecharapa, Wisanu
Within lanthanide series, Sm3+(4f5) ion is relatively very complex electronic structure and similar to Dy3+(4f9) ion but both ions exhibit visible and infrared emissions. As such, characteristics (structural, thermal, optical, luminescence, etc.) of Sm3+ ion doped crystals, glass-ceramics, phosphors and glasses have been widely investigated for development of visible photonic devices, scintillators and magnetic components. In this paper, studies carried out so far on physical, structural, luminescence and optical characteristics of Sm3+-embedded glasses have been collected, tabulated and re-analysed in a systematic procedure besides our own work on P<inf>2</inf>O<inf>5</inf> + BaO + La<inf>2</inf>O<inf>3</inf> + Sm<inf>2</inf>O<inf>3</inf> (PBaLaSm) glasses. All the quantified properties have also been reviewed besides the labeling of glass compositions in a meaningful way. The properties that are reviewed include, optical energy gap, Judd-Ofelt (JO), radiative, etc. The obtained JO parameters ( × 10−20 cm2) for the present glasses are Ω<inf>2</inf> = 5.57, Ω<inf>4</inf> = 5.22 and Ω<inf>6</inf> = 3.37. In the case of Sm3+ ion, it has been noticed that the JO analysis found to be not only sensitive to the co-ordination geometry of the surrounded glass composition but also on the number of absorption levels that are used for the JO analysis. Theoretical radiation shielding results for the studied glass found to be better than the RS-253-G18, RS-360, lead and ordinary concrete at 30 and 40 KeV. The decay rates for 4G<inf>5/2</inf> level of Sm3+ ions in the PBaLaSm glasses have been measured and are found to exhibit single exponential nature at lower concentration and turns into non-exponential at higher concentrations (≥1.0 mol % Sm<inf>2</inf>O<inf>3</inf>-doped glasses). The experimental lifetimes for 4G<inf>5/2</inf> level of Sm3+ ions are found to decrease from 2413, 2383, 2129, 2039, 1299 and 259 μs when concentration increases from 0.01, 0.05, 0.1,0.5, 1.0 and 2.0 mol % due to cross-relaxation energy transfer. The non-exponential decay rates are well-fitted to Inokuti-Hirayama model for S = 6, indicates that the energy transfer is of dipole-dipole type. However, the overall observations outlined in this study for 48 Sm3+:glasses may be quite useful for those who are interested in this thrust area to plan and carryout systematic study to get constructive conclusion besides predictive nature.
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Structural, morphological, optical, and electrochemical properties of Zn-doped CeO2/rGO nanocomposites
(2025-04-01)
Utara, Songkot
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Salidkul, Nuchjaree
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Karaphun, Attaphol
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Sonsupap, Somchai
;
Chanlek, Narong
Metal-doped cerium oxide has recently attracted the interest of researchers worldwide because of its various applications in different fields such as supercapacitors, high-sensitivity electrodes or photocatalytic. Metal-doped cerium oxide can be improved utilizing a variety of metals and composites with enhanced conductivity, which advances materials science in semiconductor processing. In this study, undoped and Zn-doped CeO<inf>2</inf> nanoparticles at 5, 10, 15, and 20 at.% were reacted with reduced graphene oxide (rGO) using a hydrothermal method. They were heated at 150 °C for 12 h and then processed in an ultrasonic reactor (20 kHz) at 25 ± 1 °C. Their structural, morphological, elemental, optical, and electrochemical properties were systematically characterized. The calculated average crystallite sizes of CeO<inf>2</inf> peaks ranged from 4.60 ± 0.2 to 12.0 ± 0.4 nm. These samples exhibited a single CeO<inf>2</inf> phase corresponding to a face-centered cubic structure, except for 20 at.% Zn-doped CeO<inf>2</inf>/rGO, which presented a ZnO phase. The samples had lower band gap values than expected for undoped CeO<inf>2</inf> nanoparticles, higher valence states due to their Ce3+/Ce4+ ratios, and a large surface area, 242 m2/g, due to Zn-doping in CeO<inf>2</inf> samples. The highest specific capacitance values achieved were 88.49 F/g at 5 mV/s and 134.01 F/g at 0.5 A/g for undoped CeO<inf>2</inf>/rGO. Zn-doping resulted in decreased capacitive behavior with specific capacitance values in the range of 70.78–81.00 F/g at 5 mV/s and 79.24–101.43 F/g at 0.5 A/g. This study for synthesizing Zn/CeO<inf>2</inf>/rGO ternary nanocomposites produced materials with improved band gaps, valence states of Ce3+/Ce4+ ratios, and greater surface area for improved electrocatalytic performance.
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Topology of boron substitutional defects in single-walled carbon nanotubes: A first-principles study
(2024-06-01)
Prachamon, Wutthisak
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Jaiboon, Oruethai
;
Komin, Sittipong
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Ruttanapun, Chesta
;
Limpijumnong, Sukit
This is a theoretical study of boron-doped single-walled carbon nanotubes. The same topology of primitive nanodomains, located at different positions on single-walled carbon nanotubes, leads to different electronic band structures. We propose a ϕ term. Density functional theory was corrected for van der Waals interactions and used to carry out the periodic boundary condition geometry optimization, where boron formed the topologies of primitive nanodomains. The calculated bulk structure and local structure spectroscopic parameters can be used for comparison with experimental results to confirm the theoretical models.

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