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Keywords:

  • sintering;
  • laser ceramics;
  • millimetre-wave;
  • gyrotron

Abstract

The distinctive features of the millimeter-wave sintering which make a method appealing for fabrication of optical ceramics are discussed. Among them are the absence of high temperature resistive heaters and the problem of their service life, favorable for elimination of porosity the inverse temperature distribution inherent in the volumetric microwave heating, highly uniform distribution of the millimeter-wave energy in applicators allowing for the sintering of large-size articles. This paper reports the results of the research on fabrication of optically transparent ceramics of compositions Nd:Y2O3, Yb:YAG, and Yb:(LaY)2O3 using a gyrotron-based set-up operating at frequency of 24 GHz. The green bodies of different compositions were compacted from powders produced by different methods: Nd:Y2O3 from the powder synthesized by laser evaporation of the target, Yb:YAG from a mixture of commercial powders, Yb:(LaY)2O3 from powder fabricated by self-propagating high-temperature synthesis. Laser oscillation was obtained from the sintered samples of all compositions. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)