Transparent compact ceramics: Inherent physical issues

Krell, Andreas; Klimke, Jens; Hutzler, Thomas

doi:10.1016/j.optmat.2008.12.009

Cited by 255 publications

(199 citation statements)

References 16 publications

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“…Although the light scattering is beneficial for images quality, when excessive, it leads to significant signal output reduction which is obviously deleterious for an image quality. Scattering of light occurs in optically inhomogeneous materials due to the different refractive index and in non-isotropic crystals by birefringence [4]. It has been shown theoretically [5,6] and demonstrated in practice [7] that diminishing scattering losses in polycrystalline layers is possible in phosphor bodies of reduced grain sizes well below the (emitted) radiation wavelength.…”

Section: Introductionmentioning

confidence: 99%

On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

et al. 2016

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In the present work, we demonstrate the fabrication technique of highly translucent layers of nanoparticulated (*50 nm) LuPO 4 :Eu phosphor, present their basic luminescent properties and give results of their performance in a planar imaging system coupled to a CMOS photodetector. For comparison, the imaging performance of an opaque Gd 2 O 2 S:Eu phosphor screen prepared by sedimentation is also shown. The X-ray detection parameters as well as the luminescence efficiency of the investigated films were discussed. Results show that the in-line transmittance at *600-700 nm, in the range of the phosphor luminescence, varies with respect to the thickness of the films from 40 to 50 % for a film of 67 lm thick to 4-12 % when the thickness increases to 460 lm. Yet, X-ray detection parameters get enhanced as the thickness of the films increases. Those results affect the luminescence efficiency curves of the films under poly-energetic X-ray radiation of various tube energies. The normalized noise power spectrum values were found similar for LuPO 4 :Eu films and a phosphor screen made using commercial Gd 2 O 2 S:Eu powder. The detective quantum efficiency of our films is clearly lower compared to the Gd 2 O 2 S:Eu screen from 2 to 10 cycles mm -1 frequency range while the modulation transfer function is lower from 0 to 5.5 cycles mm -1 frequency range. The acquired data allow to predict that high-temperature sintering of our films under pressure may help to improve their imaging quality, since such a processing should increase the luminescence efficiency without significant growth of the grains and thus without sacrificing their translucent character.

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Section: Introductionmentioning

confidence: 99%

On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

et al. 2016

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“…1). [13][14][15] MgO nanocube ensembles have been the subject of numerous previous investigations and are perhaps some of the best understood ceramic nanomaterials. [16][17][18][19] In previous work, a variety of spectroscopic techniques [20][21][22][23][24][25] as well as first-principles theoretical calculations [26][27][28][29] have been used to investigate the electronic properties of MgO nanocubes formed by the controlled combustion of magnesium vapor.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence quenching in compressed MgO nanoparticle systems

Siedl

Koller

Sternig

et al. 2014

Phys. Chem. Chem. Phys.

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Efficient use of highly dispersed metal oxides for lighting, energy conversion and catalysis requires knowledge about the impact of density and microstructure of the powders on the optical nanoparticle properties. For MgO nanocube powders we present a combined photoluminescence (PL) and electron paramagnetic resonance (EPR) approach which enables for samples of different aggregation states the quantification of the fractional powder volume that becomes illuminated with UV and visible light during the PL measurements. Using O 2 as a PL emission quencher and -after light induced exciton separation and oxygen adsorption -as an EPR active adsorbate we observed clear aggregation dependent trends in PL emission quenching that originate from particle-particle contacts. Upon interaction of low coordinated surface elements with the surfaces of adjacent MgO nanocubes, which occurs even at powder consolidation levels that escape sorption analysis, the radiative decay of excited surface states becomes quenched down to 15% of the original intensity. Our results underline the critical role of microstructure and the aggregation state of a nanoparticle ensemble with respect to spectroscopic properties and related adsorption induced changes.

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“…For both mechanical and economical reasons, numerous studies have been performed over recent years to replace sapphire by transparent polycrystalline alumina (PCA) in various optical applications such as discharge lamp envelopes and optical windows or armour [1][2][3][4][5]. The light transmission properties of fine-grained PCA can be described by the Apetz and van Bruggen model [6], based on the Rayleigh-GansDebye approximation.…”

Section: Introductionmentioning

confidence: 99%