Effects of rare earth oxides on microstructures and thermo-physical properties of hafnia ceramics
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2021年第13期
论文作者：Chun Li Chaolong Ren Yue Ma Jian He Hongbo Guo
摘 要：Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88（Ln=Gd,Yb,Gd+Yb or La+Yb）,were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite（F） structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore（P）and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m-1 K-1 at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients（TECs） of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3 × 10-6 K-1 in temperature range between 200-1200℃.
Chun Li1，Chaolong Ren1，Yue Ma1,2，Jian He1,2，Hongbo Guo1,2
1. School of Materials Science and Engineering, Beihang University2. Key Laboratory of High-temperature Structural Materials & Coatings Technology (Ministry of Industry and Information Technology), Beihang University
摘 要：Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88（Ln=Gd,Yb,Gd+Yb or La+Yb）,were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite（F） structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore（P）and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m-1 K-1 at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients（TECs） of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3 × 10-6 K-1 in temperature range between 200-1200℃.
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