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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.

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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.