Marcin Wójtowicz - Academia.edu (original) (raw)
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Papers by Marcin Wójtowicz
Optical Materials, 2009
Crystal structures of hafnia are discussed and it is shown that addition of about 7 at.% of Lu to... more Crystal structures of hafnia are discussed and it is shown that addition of about 7 at.% of Lu to the HfO 2 host lattice enforces the mixed composition to crystallize in cubic structure even at room temperature. Without Lu HfO 2 crystallizes in monoclinic structure. Luminescence and luminescence excitation spectra of Hf 0.93 Lu 0.07 O 1.965 are presented and discussed for powders prepared at different temperatures (600-1000°C) and with different content of Eu. It is shown that decay of the 595.4 nm luminescence is longer (2.5 ms) than the 610 nm (1.6 ms). Radioluminescence efficiency of the cubic Hf 0.93 Lu 0.07 O 1.965 is low and does not exceed 10% of the commercial Gd 2 O 2 S:Eu.
Optical Materials, 2008
Powder samples of Lu 2 O 3 with the following mean size of crystallites: 6 nm, 50 nm and 150 nm w... more Powder samples of Lu 2 O 3 with the following mean size of crystallites: 6 nm, 50 nm and 150 nm were structurally and spectroscopically characterized. XRD patterns and TEM images as well as luminescence, luminescence excitation and reflectance spectra were recorded. The measurements revealed profound differences in luminescent properties of the three specimens and basically all the variations scaled with the size of crystallites. For larger particles complex luminescence spectra with at least four components around 255 nm, 317 nm, 340 nm and 450 nm were observed. For the smallest crystallites only the last two, defect-related constituents could be recorded. Excitation into the host-lattice fundamental absorption, below 210 nm, was progressively less effectively converted into luminescent photons as the crystallites were getting smaller. Excitation and reflectance spectra did not show any signs of quantum confinement down to 6 nm.
Optical Materials, 2009
Crystal structures of hafnia are discussed and it is shown that addition of about 7 at.% of Lu to... more Crystal structures of hafnia are discussed and it is shown that addition of about 7 at.% of Lu to the HfO 2 host lattice enforces the mixed composition to crystallize in cubic structure even at room temperature. Without Lu HfO 2 crystallizes in monoclinic structure. Luminescence and luminescence excitation spectra of Hf 0.93 Lu 0.07 O 1.965 are presented and discussed for powders prepared at different temperatures (600-1000°C) and with different content of Eu. It is shown that decay of the 595.4 nm luminescence is longer (2.5 ms) than the 610 nm (1.6 ms). Radioluminescence efficiency of the cubic Hf 0.93 Lu 0.07 O 1.965 is low and does not exceed 10% of the commercial Gd 2 O 2 S:Eu.
Optical Materials, 2008
Powder samples of Lu 2 O 3 with the following mean size of crystallites: 6 nm, 50 nm and 150 nm w... more Powder samples of Lu 2 O 3 with the following mean size of crystallites: 6 nm, 50 nm and 150 nm were structurally and spectroscopically characterized. XRD patterns and TEM images as well as luminescence, luminescence excitation and reflectance spectra were recorded. The measurements revealed profound differences in luminescent properties of the three specimens and basically all the variations scaled with the size of crystallites. For larger particles complex luminescence spectra with at least four components around 255 nm, 317 nm, 340 nm and 450 nm were observed. For the smallest crystallites only the last two, defect-related constituents could be recorded. Excitation into the host-lattice fundamental absorption, below 210 nm, was progressively less effectively converted into luminescent photons as the crystallites were getting smaller. Excitation and reflectance spectra did not show any signs of quantum confinement down to 6 nm.