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[摘要]：The structural attributes of the polyamorphic high-and low-density amorphous phases in Y(2)O(3)-Al(2)O(3) glasses with 24-41 mol % Y(2)O(3) have been investigated using high-resolution (27)Al and (89)Y nuclear magnetic resonance spectroscopy in combination with back-scattered electron and transmission electron microscopy imaging and differential scanning calorimetric measurements. Glasses over the entire composition range are characterized by a uniform dispersion of droplets of one phase in the matrix of the other phase resulting from a density-driven phase separation in the supercooled liquid state. Although compositionally identical, the structures of the two phases differ primarily in their Y coordination environment and in the structural order associated with the connectivity and packing of the Al-O and Y-O coordination polyhedra. It appears that, compared to the matrix phase, the droplet phase is characterized by a significantly higher degree of short-range structural order. |
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