Electronic and optical properties of Y 2 SiO 5 and Y 2 Si 2 O 7 with comparisons to α-SiO 2 and Y 2 O 3
Electronic and optical properties of Y 2 SiO 5 and Y 2 Si 2 O 7 with comparisons to α-SiO 2 and Y 2 O 3
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DOI：
10.1103/physrevb.67.245108
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发表时间：
2003-06
影响因子：
3.7
通讯作者：
W. Ching;L. Ouyang;Yong-nian Xu
中科院分区：
文献类型：
--
作者：
W. Ching;L. Ouyang;Yong-nian Xu
用第一性原理局域密度计算方法研究了氧化硅酸钇y2sio5和焦硅酸钇y2si2o7两种复杂晶体的电子结构和键合。两种晶体都是具有大带隙的离子绝缘体。结果表明，它们的电子结构和成键不能用α- sio2和y2o3的加权和来表示。平均而言，三元晶体中的Si-O （YO）键比α- sio2 （y2o3）中的相应键更弱（更强）。进一步表明，特定的局部原子配位可以导致明显不同的态的部分密度，应该是实验可检测的。计算了这两种晶体的体积和光学性质。我们发现y2sio5 （y2si2o7）的体积模量为134.8 GPa （140.2 GPa）。两种晶体的介电常数分别为3.11和3.44。在没有任何实验数据的情况下，这些值作为理论预测。
The electronic structure and bonding in two complex crystals, yttrium oxyorthosilicate Y 2 SiO 5 and yttrium pyrosilicate Y 2 Si 2 O 7, were studied by means of first-principles local density calculations. Both crystals are ionic insulators with large band gaps. It is shown that their electronic structure and bonding cannot be represented by the weighted sums of those of α-SiO 2 and Y 2 O 3. On average, the Si-O (YO) bond in the ternary crystals tends to be weaker (stronger) than the respective bond in α-SiO 2 (Y 2 O 3). It is further shown that the specific local atomic coordinations can lead to significantly different partial density of states that should be experimentally detectable. The bulk and optical properties of these two crystals were also calculated. We find the bulk modulus of Y 2 SiO 5 (Y 2 Si 2 O 7) to be 134.8 GPa (140.2 GPa). The optical dielectric constants for the two crystals are estimated to be 3.11 and 3.44, respectively. In the absence of any experimental data, these values are presented as theoretical predictions.