Experimental evidence for the existence of an ordered structure in a silicate liquid above its liquidus temperature

The strategy of this study is to repeatedly thermally scan a basaltic glass sample up and down at a rate of 20 K/min in a differential scanning calorimeter (DSC) from 60 to 1250 °C (Tliq + 70 °C), and to 1300 °C (Tliq + 120 °C), where Tliq is the liquidus temperature, so as to observe the structural development of both crystals and the liquid above Tliq. A gradual transformation from a polycrystalline to a mono-crystalline phase occurs during down scans, indicating that the degree of the structural ordering of the liquid at T > Tliq increases, when the up- and -down scans are repeated. The liquid remembers the structure of its previous crystalline state. The ordered structure of the liquid favors the structure of one stable, mono-crystalline phase. The degree of the structural ordering of the liquid decreases as the maximum up scanning temperature (above Tliq) is raised. Furthermore, the present paper discusses several aspects of the industrial significance of the new experimental approach and the findings about the ordered structure in the system above its Tliq.