摘要
The influences of equimolar substitution of yttria by gadolinia on the phase constituent and stability for Y203- Ta2Os-Zr02 ceramics have been investigated. The ceramics with the Gd content lower than 8 tool% exhibit pure tetragonal phase as well as high tetragonal phase stability. However, the high Gd containing ceramics consist of t-Zr02, m-Zr02 and monoclinic GdTa04 and show complicated phase evolution behaviors. The fractions of monoclinic Zr02 and GdTa04 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.
The influences of equimolar substitution of yttria by gadolinia on the phase constituent and stability for Y203- Ta2Os-Zr02 ceramics have been investigated. The ceramics with the Gd content lower than 8 tool% exhibit pure tetragonal phase as well as high tetragonal phase stability. However, the high Gd containing ceramics consist of t-Zr02, m-Zr02 and monoclinic GdTa04 and show complicated phase evolution behaviors. The fractions of monoclinic Zr02 and GdTa04 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.
基金
the financial support for this research by the National Natural Science Foundation of China under Grant No.50974074
the Program for New Century Excellent Talents in University under Grant No.NCET-10-0910
the Natural Science Foundation of Inner Mongolia under Grant No.2011ZD09
