Atomic Structural Origin of Fictive Temperature Revealed by AZnP3O9 (A=K,Rb) Glasses

The fictive temperature (T_f) is widely applied to understand the relaxation thermodynamics of a glass; however, its atomic structural origin is still unclear. Here, we report two novel AZnP₃O₉ glasses obtained by melting the composition identical single crystals. These glasses exhibit structural inheritance within 5 Å from the single crystal counterparts that is quantified by δ=n_glass/n_cry (0≤δ≤1, n is the number of pair correlation functions). Among the available glass-formers, ^glassKZnP₃O₉ exhibits the highest structural inheritance (δ=1, n_glass=8). More insightfully, a reverse correlation between δ and the relaxation thermodynamic parameters is observed in ^glassAZnP₃O₉, revealing for the first time the atomic structural origin of fictive temperature.