Effects of Dislocations on Growth Habit in Crystal of Thallium Acid Phthalate

The spiral and ordinary dislocations both running nearly perpendicular to the (001) growth surface of thallium acid phthalate, were revealed and identified by x-ray topography. They play an unexpectedly important role on that face by providing the self-perpetuating step sources so as to accelerate its growth rate or even to change its crystal morphology.