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Proceedings Paper

Quantitative microstructural characterization of transparent YAG ceramics via microscopic image analysis using stereological relations
Author(s): Tereza Uhlířová; Jan Hostaša; Willi Pabst; Laura Esposito
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Paper Abstract

The microstructure of transparent yttrium-aluminum garnet (YAG) ceramics is characterized using different microstructural descriptors, with special focus on grain size numbers. Both linear and planar grain size numbers are used to describe the dependence of the average grain size on Yb dopant content (0-10 at.%), sintering additive (tetraethyl orthosilicate, TEOS) content (0.3-0.5 wt.%) and firing time. Although the two grain size numbers are very close for the materials studied (with ratios very close to unity, around 0.987 ± 0.109), these two numbers are principally independent and provide complementary microstructural information. Their relations to other microstructural descriptors (interface density, mean curvature integral density, mean chord length, Jeffries size) are discussed throughout the text. It is found that Yb doping of more than 3 at.% has a grain-growth-inhibiting effect (after sufficiently long firing times), but differences in the TEOS content between 0.3 and 0.5 wt.% do not have any sensible effect. The largest effect on the microstructure is exerted by the firing time (with prolonged firing times leading to grain growth), but with higher Yb doping the effect of firing time on the grain size becomes less pronounced: for YAG samples without Yb doping, increasing the firing time by a factor of 8 (from 2 h to 16 h), deceases the grain size number by 33.2-35.0 %, whereas with a Yb dopant content of 10 at.%, the corresponding decrease in the grain size number is only 8.7-10.0 %. These findings are fully corroborated using the other microstructural descriptors.

Paper Details

Date Published: 7 January 2015
PDF: 10 pages
Proc. SPIE 9442, Optics and Measurement Conference 2014, 94421C (7 January 2015); doi: 10.1117/12.2179239
Show Author Affiliations
Tereza Uhlířová, Institute of Chemical Technology (Czech Republic)
Jan Hostaša, Institute of Chemical Technology (Czech Republic)
Istituto di Scienza e Tecnologia dei Materiali Ceramici (Italy)
Willi Pabst, Institute of Chemical Technology (Czech Republic)
Laura Esposito, Istituto di Scienza e Tecnologia dei Materiali Ceramici (Italy)

Published in SPIE Proceedings Vol. 9442:
Optics and Measurement Conference 2014
Jana Kovačičinová; Tomáš Vít, Editor(s)

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