1. Figure 7.1 Thermodynamic representation of the change in enthalpy as a material crystallizes from a liquid to form a solid phase (reproduced from Glicksman (2011), with kind permission from Springer Science+Business Media B.V.).

2. Figure 7.2 The 14 distinct Bravais lattices.

3. Figure 7.3 The six basic habits described in the USP.

4. Figure 7.4 Thermodynamic representation of the formation of polymorphs.

5. Figure 7.5 Schematic representation of the change in free energy with temperature for two monotropic polymorphs.

6. Figure 7.6 Schematic representation of the change in free energy with temperature for two enantiotropic polymorphs.

7. Figure 7.7 Schematic representation of polymorphic forms of a drug (top left and right) as well as a monohydrate or solvate (bottom left) and a co-crystal (bottom right).

8. Figure 7.8 Blood plasma concentrations versus time for two polymorphs of chloramphenicol palmitate (redrawn from Aguiar et al. (1967), with permission from John Wiley & Sons, Inc.).

9. Figure 7.9 Overview of crystalline forms.

10. Figure 7.10 DSC thermal traces showing the melting of paracetamol form I (initial heat), quench cooling to form a glass (cool) and crystallisation to and melting of the metastable form II (second heat) (data courtesy of Asma Buanz).

11. Figure 7.11 XRPD diffractograms for two polymorphs of sulphapyridine (data courtesy of Asma Buanz)

12. Figure 7.12 Schematic DSC thermal trace showing melt of the stable form of a polymorph.

13. Figure 7.13 Schematic representation of the DSC thermal traces for a metastable polymorph on its first (top) and second (bottom) heating runs.

14. Figure 7.14 DSC thermal trace for an enantiotropically related pair of sulphathiazole polymorphs (top, courtesy of Asma Buanz) and a series of monotropically related premafloxacin polymorphs (bottom, redrawn from Schinzer et al. (1997)).

15. Figure 7.15 Schematic representation of the DSC thermal traces for a metastable polymorph at slow (top) and fast (bottom) heating rates.

16. Figure 7.16 Schematic representation of the theoretical position of the crystallisation exotherm when a very fast heating rate is used.

17. Figure 7.17 Determination of the minimum heating rate required to inhibit a kinetic event.

18. Figure 7.18 Schematic DSC thermal traces for an irreversible hydrate (top) and a reversible hydrate (bottom).

19. Figure 7.19 DSC and TGA thermal traces for a metastable polymorph (top) and an irreversible hydrate (bottom).