Herstellung polykristalliner Szintillatoren für die Positronen-Emissions-Tomographie (PET)

Karim, Kamran Said

Dissertation / PhD Thesis/Book

Herstellung polykristalliner Szintillatoren für die Positronen-Emissions-Tomographie (PET)

Karim, K. S. (Corresponding author)FZJ*

2010
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-89336-610-1

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Schriften des Forschungszentrums Jülich : Energie & Umwelt / Energy & Environment 55, VI, 154 S. (2010) = Univ. Bochum, Diss., 2010

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Please use a persistent id in citations: http://hdl.handle.net/2128/3726

Abstract: Transparent ceramics are becoming more and more important for two new types of applications. On the one hand in cases where high mechanical and thermal demands in combination with optical properties are required, on the other hand where the optical properties of transparent materials like glass are not sufficient e.g. in positronemission-tomography (PET) diagnostics. Most state of the art PET-scanners are using high-priced single crystals as scintillator material. The technological challenge is to replace single crystal by cost-efficient transparent ceramics. Producing transparent ceramics is ordered in synthesis of the powders and in manufacturing of these into transparent ceramics. The aim of this work was to synthesize single phase yttrium-alumina-and Luthetiumalumina- garnet (YAG, LuAG) powders partially doped with neodymium or praseodymium by four different synthesis routes (Pechini-synthesis, sol-gel-route, coprecipitation and solid state reactions). Additionally industrial LuAG and LuPO4 powders were characterized and manufactured. The powders were processed as submicron- and nanopowders. Newly produced single-phase powders were homgenized with additions of sintering additives like tetraethyl orthosilicate (TEOS) and binders like polyvinyl alcohol (PVA). Moulding the powders were carried out by unaxial pressing, cold isostatic pressing and in individual cases also by slip casting. The achieved green densities were in a range of 25-42 %. Examination of calcination behaviour leads to a calcination temperature of 1000 °C with 2 hours dwell time in air atmosphere. Only solid state reactions resulted into transparent YAG, YAG:Pr, LuAG, LuAG:Pr ceramics. Solid state reactions of nanopowders resulted in heterogeneously transparent samples. Ceramics made by powders of other synthetic routes gave nontransparent ceramics due to porosity and additional phases. Transmission measurements of the manufactured transparent ceramics showed in classical one step sintering and two step sintering program significant lower transmission than respectitive single crystals but similar transmission compared to ceramics reported in literature.

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