Publications by authors named "Gandham Lakshminarayana"

For both the BO-BiO-CaO and BO-BiO-SrO glass systems, -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.

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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).

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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.

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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.

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