POLYMORPHISM, TWINNING AND MORPHOLOGY OF CRYSTALS OF 2,4,6-TRINITROTOLUENE GROWN FROM SOLUTION

Crystals of 2,4,6-trinitrotoluene (TNT) have been grown from a wide ra nge of organic solvents under various conditions. The structural natur e and morphology of these crystals were systematically characterised u sing a number of techniques. The crystals were found to exist in two b asic forms having monoclinic and orthorhombic structures. The monoclin ic modification was the stable form from ambient temperature to the me lting point and showed extensive twinning: the twin law was defined an d the structural origin of twinning determined. The variation in cryst al morphology with growth conditions for the monoclinic modification w as attributed to the small differences in reticular areas for morpholo gical forms other than {100}. The structural perfection of monoclinic crystals was shown to be dominated by impurity-related defects.