a b s t r a c tWe employed a sol-gel route followed by a thermal treatment (up to 1000 1C) to prepare crystalline (monoclinic) hafnium dioxide. Thorough steady-state and time-resolved photoluminescence characterization of the material within the temperature range of 10-300 K was conducted by using various excitation sources. The most prominent spectroscopic feature of the material was an intense broad emission band centered at 2.3-2.5 eV with an associated excitation band centered at 4.2-4.4 eV (well below the bandgap of monoclinic hafnia). The emission was characterized by an essentially nonexponential, thermally stimulated decay and exposed a marked blue shift with the increase of temperature from 10 to 300 K. Relation of the emission to the intrinsic defects of hafnia is discussed.
The paper explores the structure and luminescence of sol-gel-derived SnO 2 :Eu and SnO 2 :Eu,Sb nanopowders which may be useful as electrically conductive phosphors. The samples were sintered in air at temperatures reaching up to 1400°C. Raman-, SEM-, EDX-and photoluminescence characterization of the samples was carried out.High-temperature annealing of SnO 2 :Eu leads to a nanoparticulate phosphor with considerable efficiency of host-sensitized Eu 3+ emission under UV excitation although the emission is slightly quenched at room temperature. While Sb co-dopant immensely improves crystallization at 1400°C, it also impairs luminescence performance. SEM and EDX characterization suggest pronounced segregation of Eu induced by the enhanced crystal growth. Interestingly, Sb-doping seems to activate in the Raman spectrum quite a few SnO 2 vibrations which are normally rather weak or IR active.
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