Kinetics of physical aging in archetypic 45S5 bioactive silicate glass composition with different types of phase separation are studied in situ below the glass transition temperature (Tg). The qualitative nature of aging is found to be almost independent of the structural differences on the micrometer scale. A well-expressed step-like behaviour in the enthalpy recovery kinetics is observed for aging temperatures Ta~0.90Tg and Ta~0.85Tg, which, however, disappears when the aging occurs at Ta ~0.95Tg. The overall kinetics is described by a stretched-exponential function with stretching exponent close to 3/7 at Ta ~0.95Tg, and 1/3 when the aging temperature drops to ~0.90Tg and below. The values correlate well with the predictions of Phillips' diffusion-to-traps and percolating fractals models. Appearance of step-like behaviour at larger departure from Tg is attributed to the hierarchical scheme of approaching equilibrium based on an alignment-shrinkage mechanism of physical aging proposed earlier for chalcogenide glasses.

中文翻译：

---

生物活性 45S5 玻璃结构弛豫动力学

在玻璃化转变温度 (Tg) 以下原位研究了具有不同类型相分离的原型 45S5 生物活性硅酸盐玻璃组合物中的物理老化动力学。发现老化的定性性质几乎与微米级的结构差异无关。对于时效温度 Ta~0.90Tg 和 Ta~0.85Tg，观察到焓恢复动力学中表现良好的阶梯状行为，然而，当在 Ta~0.95Tg 发生时效时，这种行为消失。整体动力学由拉伸指数函数描述，在 Ta ~0.95Tg 时拉伸指数接近 3/7，在老化温度降至 ~0.90Tg 及以下时为 1/3。这些值与 Phillips 的扩散到陷阱和渗透分形模型的预测非常相关。