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    Université de Fribourg

    Prospecting lighting applications with ligand field tools and density functional theory: a first-principles account of the 4f⁷–4f⁶5d¹ Luminescence of CsMgBr₃:Eu²⁺

    Ramanantoanina, Harry ; Cimpoesu, Fanica ; Göttel, Christian ; Sahnoun, Mohammed ; Herden, Benjamin ; Suta, Markus ; Wickleder, Claudia ; Urland, Werner ; Daul, Claude

    In: Inorganic Chemistry, 2015, vol. 54, no. 17, p. 8319–8326

    The most efficient way to provide domestic lighting nowadays is by light-emitting diodes (LEDs) technology combined with phosphors shifting the blue and UV emission toward a desirable sunlight spectrum. A route in the quest for warm-white light goes toward the discovery and tuning of the lanthanide-based phosphors, a difficult task, in experimental and technical respects. A proper theoretical...

    Université de Fribourg

    Tailoring the optical properties of lanthanide phosphors: prediction and characterization of the luminescence of Pr3+-doped LiYF4

    Ramanantoanina, Harry ; Urland, Werner ; Herden, Benjamin ; Cimpoesu, Fanica ; Daul, Claude

    In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 14, p. 9116–9125

    We present a theoretical work detailing the electronic structure and the optical properties of (PrF₈)⁵⁻ embedded in LiYF₄, complementing the insight with data that are not available by experimental line. The local distortions due to the embedding of the lanthanide ion in the sites occupied in the periodic lattice by smaller yttrium centres, not detectable in regular X-ray analyses, are...

    Université de Fribourg

    A ligand field theory-based methodology for the characterization of the Eu²⁺ [Xe]4f⁶5d¹ excited states in solid state compounds

    García-Fuente, Amador ; Cimpoesu, Fanica ; Ramanantoanina, Harry ; Herden, Benjamin ; Daul, Claude ; Suta, Markus ; Wickleder, Claudia ; Urland, Werner

    In: Chemical Physics Letters, 2015, vol. 622, p. 120–123

    The theoretical rationalization of the open-shell 4f and 5d configuration of Eu²⁺ is by far not trivial because it involves a non-standard version of ligand field theory, based on a two-shell Hamiltonian. Here we present our methodology based on ligand field theory, taking the system CsCaBr₃:Eu²⁺ as a case study with an octahedral coordination sphere of Eu²⁺. The ligand field,...

    Université de Fribourg

    Photon cascade emission in Pr³⁺ doped fluorides with CaF₂ structure: Application of a model for its prediction

    Herden, Benjamin ; García-Fuente, Amador ; Ramanantoanina, Harry ; Jüstel, Thomas ; Daul, Claude ; Urland, Werner

    In: Chemical Physics Letters, 2015, vol. 620, p. 29–34

    In this work, we predict and measure the optical behaviour of Pr³⁺ in different binary and ternary fluorides. We use a validated model based on Ligand Field Theory and Density Functional Theory to calculate the multiplet energy levels arising from the ground [Xe]4f² and excited [Xe]4f¹5d¹ electron configurations of Pr³⁺ in its chemical environment. Moreover, the luminescence spectra of...