Role of Water Vapor in Crystallite Growth and Tetragonal‐Monoclinic Phase Transformation of ZrO2
Tóm tắt
The role of water vapor in crystallite growth and the tetragonal‐to‐monoclinic phase transformation of ZrO2 was studied using three specially prepared samples: an ultrafine powder of monoclinic ZrO2 obtained by hydrolysis of ZrOCI2, an aggregated powder of tetragonal ZrO2 obtained by thermal decomposition of Zr(OH)4 under reduced pressure, and an ultrafine powder of tetragonal ZrO2 obtained by thermal decomposition of zirconyl acetate dispersed in caramel. The samples were heat‐treated up to 1000°C in dry and wet atmospheres saturated with water vapor at 90°C. It was found that water vapor markedly accelerated crystallite growth for both monoclinic and tetragonal ZrO2 and facilitated the tetragonal‐to‐monoclinic phase transformation. Water vapor increases surface diffusion and thus enhances crystallite growth and decreases surface energy, which leads to stabilization of the tetragonal phase.
Từ khóa
Tài liệu tham khảo
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