Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
J Chem Phys. 2013 Mar 28;138(12):12A522. doi: 10.1063/1.4773356.
The constituents of any network glass can be broadly classified as either network formers or network modifiers. Network formers, such as SiO2, Al2O3, B2O3, P2O5, etc., provide the backbone of the glass network and are the primary source of its rigid constraints. Network modifiers play a supporting role, such as charge stabilization of the network formers or alteration of the network topology through rupture of bridging bonds and introduction of floppy modes. The specific role of the modifiers depends on which network formers are present in the glass and the relative free energies of modifier interactions with each type of network former site. This variation of free energy with modifier speciation is responsible for the so-called mixed network former effect, i.e., the nonlinear scaling of property values in glasses having fixed modifier concentration but a varying ratio of network formers. In this paper, a general theoretical framework is presented describing the statistical mechanics of modifier speciation in mixed network glasses. The model provides a natural explanation for the mixed network former effect and also accounts for the impact of thermal history and relaxation on glass network topology.
任何网络玻璃的成分都可以大致分为网络形成体或网络改性剂。网络形成体，如 SiO2、Al2O3、B2O3、P2O5 等，提供了玻璃网络的骨架，是其刚性约束的主要来源。网络改性剂起着辅助作用，例如通过桥键的断裂和柔性模式的引入来稳定网络形成体的电荷或改变网络拓扑结构。改性剂的具体作用取决于玻璃中存在的网络形成体以及改性剂与每种网络形成体位点相互作用的相对自由能。这种自由能随改性剂形态变化的变化导致了所谓的混合网络形成体效应，即具有固定改性剂浓度但网络形成体比例变化的玻璃中性能值的非线性标度。本文提出了一个描述混合网络玻璃中改性剂形态的统计力学的一般理论框架。该模型为混合网络形成体效应提供了自然的解释，同时也考虑了热历史和弛豫对玻璃网络拓扑结构的影响。
