Glass-to-Vitroceramic Transition in the Yttrium Aluminoborate System: Structural Studies by Solid-State NMR

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• 作者：Heinz Deters ; Andrea S. S. de Camargo ; Cristiane N. Santos ; Hellmut Eckert
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：September 2, 2010
• 年：2010
• 卷：114
• 期：34
• 页码：14618-14626
• 全文大小：382K
• 年卷期：v.114,no.34(September 2, 2010)
• ISSN：1932-7455

文摘

The crystallization of laser glasses in the system (B₂O₃)_0.6{(Al₂O₃)_0.4−y(Y₂O₃)_y} (0.1 ≤ y ≤ 0.25) doped with different levels of ytterbium oxide has been investigated by X-ray powder diffraction, differential thermal analysis, and various solid-state NMR techniques. The homogeneous glasses undergo major phase segregation processes resulting in crystalline YBO₃, crystalline YAl₃(BO₃)₄, and residual glassy B₂O₃ as the major products. This process can be analyzed in a quantitative fashion by solid-state ¹¹B, ²⁷Al, and ⁸⁹Y NMR spectroscopies as well as ¹¹B{²⁷Al} rotational echo double resonance (REDOR) experiments. The Yb dopants end up in both of the crystalline components, producing increased line widths of the corresponding ¹¹B, ²⁷Al, and ⁸⁹Y NMR resonances that depend linearly on the Yb/Y substitution ratio. A preliminary analysis of the composition dependence suggests that the Yb³⁺ dopant is not perfectly equipartitioned between both crystalline phases, suggesting a moderate preference of Yb to substitute in the crystalline YBO₃ component.