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 AZnP 3 O 9 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, glass KZnP 3 O 9 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 glass AZnP 3 O 9 , revealing for the first time the atomic structural origin of fictive temperature.