取向无序混合晶体动力学的标度。

Scaling the dynamics of orientationally disordered mixed crystals.

机构信息

Department de Física I Enginyeria Nuclear, Grup de Caracterització de Materials, ETSEIB, Diagonal 647, Universitat Politècnica de Catalunya, Barcelona 08028, Catalonia, Spain.

出版信息

J Chem Phys. 2009 Nov 14;131(18):184504. doi: 10.1063/1.3254207.

DOI:10.1063/1.3254207

PMID:19916609

Abstract

The evolution of the primary relaxation time of orientationally disordered (OD) mixed crystals (CH(3))(2)C(CH(2)OH)(2)(CH(3))C(CH(2)OH)(3), with 0 < X < or = 0.5, on approaching the glass temperature (T(g)) is discussed. The application of the distortion-sensitive, derivative-based procedure revealed a limited adequacy of the Vogel-Fulcher-Tammann parametrization and a superiority of the critical-like description tau proportional to (T - T(C))(-phi(') ), phi(') = 9-11.5, and T(C) approximately T(g) - 10 K. Basing on these results as well as that of Drozd-Rzoska et al. [J. Chem. Phys. 129, 184509 (2008)] the question arises whether such behavior may be suggested as the optimal universal pattern for dynamics in vitrifying OD crystals (plastic crystals). The obtained behavior is in fair agreement with the dynamic scaling model (DSM) [R. H. Colby, Phys. Rev. E 61, 1783 (2000)], originally proposed for vitrifying molecular liquids and polymers. The application of DSM made it possible to estimate the size of the cooperatively rearranging regions ("heterogeneities") in OD phases near T(g).

摘要

本文讨论了取向无序（OD）混合晶体(CH(3))(2)C(CH(2)OH)(2)(CH(3))C(CH(2)OH)(3)（0 < X < = 0.5）在接近玻璃化温度（T(g)）时的主弛豫时间的演化。应用基于扭曲敏感的导数方法，揭示了 Vogel-Fulcher-Tammann 参数化的有限适应性和类似于临界的描述 tau 与（T-T(C))(-phi(') )成正比的优越性，phi(') = 9-11.5，T(C)大约等于 T(g) - 10 K。基于这些结果以及 Drozd-Rzoska 等人的结果[J. Chem. Phys. 129, 184509 (2008)]，出现了这样的问题，即这种行为是否可以被建议为玻璃化 OD 晶体（塑料晶体）中动力学的最佳通用模式。所得到的行为与最初为玻璃化分子液体和聚合物提出的动态标度模型（DSM）[R. H. Colby, Phys. Rev. E 61, 1783 (2000)]吻合良好。DSM 的应用使得在 T(g)附近的 OD 相中估计协同重排区域（“非均相”）的大小成为可能。