Detailed Inspection of γ-ray, Fast and Thermal Neutrons Shielding Competence of Calcium Oxide or Strontium Oxide Comprising Bismuth Borate Glasses.

For both the B2O3-Bi2O3-CaO and B2O3-Bi2O3-SrO glass systems, γ-ray and neutron attenuation qualities were evaluated. Utilizing the Phy-X/PSD program, within the 0.015-15 MeV energy range, linear attenuation coefficients (µ) and mass attenuation coefficients (µ/ρ) were calculated, and the attained µ/ρ quantities match well with respective simulation results computed by MCNPX, Geant4, and Penelope codes. Instead of B2O3/CaO or B2O3/SrO, the Bi2O3 addition causes improved γ-ray shielding competence, i.e., rise in effective atomic number (Zeff) and a fall in half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). Exposure buildup factors (EBFs) and energy absorption buildup factors (EABFs) were derived using a geometric progression (G-P) fitting approach at 1-40 mfp penetration depths (PDs), within the 0.015-15 MeV range. Computed radiation protection efficiency (RPE) values confirm their excellent capacity for lower energy photons shielding. Comparably greater density (7.59 g/cm3), larger µ, µ/ρ, Zeff, equivalent atomic number (Zeq), and RPE, with the lowest HVL, TVL, MFP, EBFs, and EABFs derived for 30B2O3-60Bi2O3-10SrO (mol%) glass suggest it as an excellent γ-ray attenuator. Additionally, 30B2O3-60Bi2O3-10SrO (mol%) glass holds a commensurably bigger macroscopic removal cross-section for fast neutrons (ΣR) (=0.1199 cm-1), obtained by applying Phy-X/PSD for fast neutrons shielding, owing to the presence of larger wt% of 'Bi' (80.6813 wt%) and moderate 'B' (2.0869 wt%) elements in it. 70B2O3-5Bi2O3-25CaO (mol%) sample (B: 17.5887 wt%, Bi: 24.2855 wt%, Ca: 11.6436 wt%, and O: 46.4821 wt%) shows high potentiality for thermal or slow neutrons and intermediate energy neutrons capture or absorption due to comprised high wt% of 'B' element in it.

The synthesis and characterization of platinum nanoparticles: a method of controlling the size and morphology.

In this paper, Pt nanoparticles with good shapes of nanocubes and nano-octahedra and well-controlled sizes in the range 5-7 and 8-12 nm, respectively, have been successfully synthesized. The modified polyol method by adding silver nitrate and varying the molar ratio of the solutions of silver nitrate and H(2)PtCl(6) has been used to produce Pt nanoparticles of the size and shape to be controlled. The size and morphology of Pt nanoparticles have been studied by transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The results have shown that their very sharp and good shapes exist in the main forms of cubic, cuboctahedral, octahedral and tetrahedral shapes directly related to the crystal nucleation along various directions of the [100] cubic, [111] octahedral and [111] tetrahedral facets during synthesis. In particular, various irregular and new shapes of Pt nanoparticles have been found. Here, it is concluded that the role of silver ions has to be considered as an important factor for promoting and controlling the development of Pt nanoparticles of [100] cubic, [111] octahedral and [111] tetrahedral facets, and also directly orienting the growth and formation of Pt nanoparticles.

Cooperative downconversion in Yb3+/-RE3+ (RE=Tm or Pr) codoped lanthanum borogermanate glasses.

We report on cooperative downconversion in Yb(3+)-RE(3+) (RE=Tm or Pr) codoped lanthanum borogermanate glasses (LBG), which are capable of splitting a visible photon absorbed by Tm(3+) or Pr(3+) ions into two near-infrared photons. The results indicate that Pr(3+)-Yb(3+) is a more efficient ion couple than Tm(3+)-Yb(3+) in terms of cooperative downconversion. We have obtained a highest quantum yield of 165% and 138% for Pr(3+)-Yb(3+) and Tm(3+)-Yb(3+) codoped LBG glasses under 468 nm excitation, respectively. However, ultraviolet light excitation to the charge transfer band of Yb(3+) does not result in quantum splitting as rapid relaxation from the charge transfer band to 4f(13) levels of Yb(3+) dominates.

Enhanced cooperative quantum cutting in Tm3+- Yb3+ codoped glass ceramics containing LaF3 nanocrystals.

Tm(3+)-Yb(3+) codoped transparent oxyfluoride glass ceramics containing LaF(3) nanocrystals were obtained by thermal treatment on the as-made glasses. The formation of LaF(3) nanocrystals and the incorporation of Tm(3+) and Yb(3+) into LaF(3) nanocrystal lattice were confirmed by X-ray diffraction and high resolution transmission electron microscopy. Infrared quantum cutting involving Yb(3+) 950-1100 nm ((2)F(5/2)--> (2)F(7/2)) emission was achieved upon the excitation of the (1)G(4) energy level of Tm(3+) at 468 nm. We measured the photoluminescence properties of these glass ceramics. We also investigated the thermal treatment duration dependent quantum efficiency, and found that the quantum efficiency is 13% increased for the 0.5Tm(3+)-4Yb(3+) doped glass ceramic with a maximum value of 144%, and 16% increased for the 0.5Tm3+-8Yb3+ doped glass ceramic with a maximum value of 162%, respectively.