Crystallisation anomaly

Fig. 14.21 Schematic illustration of the crystallisation anomaly. In B2O3, cooling the liquid at ambient pressure has so far always resulted in a glassy phase of low density, as shown schematically by the path (A). The crystallisation from the melt, path (B), is never observed underambient pressure the obtention of B2O3-I requires the melt to be pressurised before being cooled, path (C)...

In constructing an affinity table ( X), Ad is dissolved in water and a concentrated solution of c added. If c is insoluble (e.g. a metal) it is put into the solution of Ad and it is observed if a precipitate of Acy or dy or both, occurs. Ad is then treated with b and a, etc. Sometimes an excess of c is necessary and time must be given for Ac to crystallise. There are certain anomalies ( VII) modifying the order of attractions, masks (larvae) which hide decompositions. ... 

Temperature-modulated differential scanning calorimetry (T-MDSC) applies a thermal modulation in temperature to a conventional DSC mn and determines a dynamic heat capacity from the relationship between the modulation components of temperature and of heat flow. Primary application of this technique has been the measurement of specific heat capacity and the examination of the anomaly in a relaxation process such as alpha process related to the glass transition. An application to the first-order phase transitions of crystallisation and melting of polymer crystals has recently been suggested. The method and typical results are described. 13 refs. 

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