Substituent Influence of Yttria by Gadolinia on the Tetragonal Phase Stability for Y₂O₃-Ta₂O₅-ZrO₂ Ceramics at 1300℃

Xiaoqing Niu¹，Min Xie¹，Fen Zhou¹，Rende Mu²，Xiwen Song¹，Shengli An¹

1. Inner Mongolia Key Laboratory of Advanced Ceramics and Device,School of Materials and Metallurgy,Inner Mongolia University of Science and Technology2. Beijing Institute of Aeronautical Materials

摘 要：The influences of equimolar substitution of yttria by gadolinia on the phase constituent and stability for Y₂O₃—Ta₂O₅—ZrO₂ ceramics have been investigated.The ceramics with the Gd content lower than 8 nnol%exhibit pure tetragonal phase as well as high tetragonal phase stability.However,the high Gd containing ceramics consist of t-ZrO₂,m-ZrO₂ and monoclinic GdTaO₄ and show complicated phase evolution behaviors.The fractions of monoclinic ZrO₂ and GdTaO₄ increase with increasing Gd content,indicating that the excessive substitution of Gd for Y results in a reduction in the tetragonal phase stability.In addition,the lower Gd containing ceramics show an almost invariable tetragonality,while the higher Gd containing ceramics reveal a composition-dependent tetragonality.Accordingly,an association of the tetragonal phase stability and tetragonality with the Gd concentration is established,which provides us a clue to understand the phase stability of these ceramics.

关键词：