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Hydrothermal Processing of Ultrafine Single-Crystal Zirconia and Hafnia Powders with Homogeneous Dopants

  • Shigeyuki Sōmiya
  • Masahiro Yoshimura
  • Zenjiro Nakai
  • Kazumitsu Hishinuma
  • Takao Kumaki

Abstract

The crystallization of HfO2-Eu2O3 amorphous coprecipitates from the mixture of HfOCl2 and EuCl3 solution by NH4OH, was studied under hydrothermal conditions at 300°C under 10 MPa, for three hours. The products were cubic hafnia solid solution Hf1−x Eu x O2−x/2 with particle sizes about 10 nm and 8 nm for 20 wt% Eu2Q3 (x = 0.230) and 30 wt°/o Eu203 (x = 0.339), respectively. The products had a nonaggregated, uniform morphology. The maximum compositional fluctuation in the products was less than ≈2 wt% by EDS for each particle and by precise X-ray profile analysis of all diffraction lines of the cubic phase using a Williamson-Hall plotting. Y-PSZ (3 mol°/o Y2O3-doped ZrO2) powders were homogeneously precipitated under hydrothermal conditions at 160° to 220°C under 2 to 7 MPa. The products were cubic/tetragonal fine powders about 12 nm in size at 220°C. They became tetragonal at about 16 nm by calcination at 800°C for one hour. The compositional fluctuation was less than ±0.75 mol% for 2.93 mol% Y2O3 in the products.

Keywords

Crystallite Size Energy Dispersive Spectroscopy Hydrothermal Condition Energy Dispersive Spectroscopy Analysis Homogeneous Precipitation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Elsevier Science Publishers Ltd 1989

Authors and Affiliations

  • Shigeyuki Sōmiya
    • 1
  • Masahiro Yoshimura
    • 1
  • Zenjiro Nakai
    • 2
  • Kazumitsu Hishinuma
    • 2
  • Takao Kumaki
    • 2
  1. 1.Research Laboratory of Engineering MaterialsTokyo Institute of TechnologyMidori, YokohamaJapan
  2. 2.R&D DivisionChichibu Cement Co., Ltd.KumagayaJapan

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