Nd 3+ :Y 3 Al 5 O 12 laser ceramics: Influence of the size of yttrium oxide particles on sintering
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MATERIALS AND CERAMICS
Nd3+:Y3Al5O12 Laser Ceramics: Influence of the Size of Yttrium Oxide Particles on Sintering D. Yu. Kosyanova, V. N. Baumera, R. P. Yavetskiya, V. L. Voznyyb, V. B. Kravchenkoc, Yu. L. Kopylovc, and A. V. Tolmacheva a
Institute for Single Crystals, National Academy of Sciences of Ukraine, Kharkov, 61001 Ukraine b EDAPS-Lazer Ltd., Kiev, Ukraine c Institute of Radio Engineering and Electronics (Fryazino Branch), Russian Academy of Sciences, pl. Vvedenskogo 1, Fryazino, Moscow oblast, 141190 Russia e-mail: [email protected] Received August 20, 2014
Abstract—The influence of the size of Y2O3 powder particles on the structure formation and densification of Nd3+:Y3Al5O12 laser ceramics has been studied. It is shown that the use of 50- and 100-nm yttrium oxide particles makes it possible to synthesize single-phase yttrium aluminum garnet at temperatures of 1200 and 1500°C, respectively, whereas in the case of 5000-nm yttrium oxide particles 2-h exposure at a temperature of 1500°C yields only 80 wt % of the Nd3+:Y3Al5O12 phase. Bulk swelling of pressed samples during sintering of 2.94Y2O3–0.06Nd2O3–5Al2O3 powders with the size ratio of the initial particles R(Al2O3/Y2O3) ~ 5 is observed. The application of different-sized powders (R ~ 2.5) provides quantitative ratios between phases in the 3Y2O3–5Al2O3 system at which shrinkage in a temperature range of 20–1500°C is dominant. Laser ceramics 0–2 at % Nd3+:Y3Al5O12 have been obtained by the solid-phase sintering of oxide powders (R ~ 2.5). The slope efficiency for 1 at % Nd3+:Y3Al5O12 laser ceramics is found to be 33%. DOI: 10.1134/S1063774515020121
INTRODUCTION The development of laser media based on compounds with garnet structure, the single-crystal growth of which is problematic or technologically difficult, is one of the most significant achievements in the field of laser materials science of the last years [1–4]. Oxide laser ceramics combines the best properties of laser crystals (a large cross section of optical transitions and high mechanical and chemical durability) with good technological efficiency and low cost of laser glasses. There are two approaches to the fabrication of Nd3+:Y3Al5O12 (Nd:YAG) ceramics: vacuum sintering of previously synthesized Nd:YAG nanopowders and sintering of powders of initial oxides (yttrium, aluminum, and neodymium oxides) in the solid phase at Т ~ 0.85–0.9Тm. The methods of lowtemperature consolidation of Nd:YAG nanopowders at high pressures (Т ~ 0.1–0.3Тm, Р = 5–8 GPa) are not widely used in optical ceramics technology, because the thus formed ceramics have an extremely nonequilibrium structure and high concentration of residual pores (up to 100 nm in size) [5, 6]. The application of nanopowders allows one to significantly increase the sintering activity, reduce sintering temperature, and provide a competitive advantage of shrinkage processes over grain growth. One significant
problem is nanopowder agglomeration [7, 8], which leads to zonal decompaction and impedes the obtainment of pore-free ceramic s
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