کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1331451 979005 2007 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Hydrated surface structure and its impacts on the stabilization of t-ZrO2
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Hydrated surface structure and its impacts on the stabilization of t-ZrO2
چکیده انگلیسی

We first optimized the preparation conditions to 3.6–6.0 nm ZrO2 in a pure tetragonal structure (t-phase). All samples were characterized by X-ray diffraction, high-resolution transmission electron microscope, thermal analysis, Raman spectra, and infrared spectra. It is found that the surfaces of t-ZrO2 nanostructures were terminated by an amorphous hydration layer co-existing with small amounts of carbonate molecules. With the removal of hydrated surface layers under hydrothermal conditions at T>150 °C, t-ZrO2 nanostructures became thermodynamically unstable, which partially transformed into monoclinic ZrO2 (m-phase). Such a transformation occurs initially at surface regions and then develops into the bulk. High-temperature annealing in air could also remove the hydrated surface layers, which is however followed by a gradual transformation of t-ZrO2 into m-ZrO2 in both bulk and surface regions. These observations are explained in terms of the difference in surface free energies of m-ZrO2 and t-ZrO2 upon H2O adsorption.

Surfaces of t-ZrO2 were terminated by hydration layers, which completely transformed into m-ZrO2 when treating at high hydrothermal temperatures. Alternatively, hydration layers transformed into t-ZrO2 when annealing at T<700 °C. t-ZrO2 partially transformed into m-ZrO2 in both bulk and surface regions at T>700 °C.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 180, Issue 10, October 2007, Pages 2790–2797
نویسندگان
, , , ,