Molecular dynamics in supercooled P-Se liquids near the glass transition: results from 31P NMR spectroscopy.
Molecular dynamics in supercooled P-Se liquids near the glass transition: results from 31P NMR spectroscopy.
复制标题
接近玻璃化转变的过冷 P-Se 液体中的分子动力学：31P NMR 光谱的结果。
DOI：
--
复制
发表时间：
2011
影响因子：
3.3
通讯作者：
B. Aitken
中科院分区：
文献类型：
--
作者：
E. Gjersing;S. Sen;B. Aitken
本文用拉曼和（31）P核磁共振谱技术研究了P（4）Se（3）化学计量比附近的硒化磷玻璃的结构，并与未掺杂少量Ge的玻璃进行了比较。结果表明，玻璃的结构主要由P（4）Se（3）笼状分子组成。然而，尽管有这种结构相似性，但掺杂Ge导致T（g）的显著大的增加。用（31）P NMR烧孔技术研究了无Ge组分中P（4）Se（3）分子在过冷液态下的动力学行为。这些分子进行大角度旋转重新取向附近和以上的玻璃化转变的时间尺度类似于预期的剪切松弛。在T（g）附近分子旋转和剪切弛豫过程之间的这种耦合使人想起有机分子玻璃形成液体的动力学行为。然而，这种行为与先前报道的Ge掺杂的硫化砷液体（含有类似结构的As（4）S（3）笼分子）的分子旋转和剪切弛豫之间的大时间解耦形成鲜明对比。
The structure of phosphorus selenide glasses with compositions close to the P(4)Se(3) stoichiometry with and without doping with a few atom % Ge has been investigated with Raman and (31)P NMR spectroscopic techniques. The results indicate that the structure of these glasses consists predominantly of P(4)Se(3) cage molecules. However, in spite of this structural similarity, doping with Ge results in a remarkably large increase in T(g). The dynamical behavior of the constituent P(4)Se(3) molecules in the Ge-free composition is investigated with a (31)P NMR hole-burning technique in the supercooled liquid state. These molecules perform large angle rotational reorientations near and above the glass transition with time scales similar to those expected for shear relaxation. Such coupling between molecular rotation and shear relaxation processes near T(g) is reminiscent of the dynamical behavior of organic molecular glass-forming liquids. However, this behavior is in stark contrast with the large temporal decoupling between molecular rotation and shear relaxation previously reported for a Ge-doped arsenic sulfide liquid that contained similarly structured As(4)S(3) cage molecules.