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

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


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.


Crystallite Size Energy Dispersive Spectroscopy Hydrothermal Condition Energy Dispersive Spectroscopy Analysis Homogeneous Precipitation 
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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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