In-situ temperature field measurements and direct observation of crystal/melt at vertical Bridgman growth of lead chloride under stationary and dynamic arrangement

• Study of lead chloride crystal growth by vertical Bridgman method.
• Influence of growth conditions on position and shape of crystal/melt interface.
• Direct observation of crystal/melt interface at stationary and dynamic conditions.
• Direct temperature field measurements during simulated crystal growth.
• Temperature data displayed as isotherms used to describe crystal/melt interface.

Influence of growth conditions, i.e. temperature gradient in the furnace and the pulling rate, on the position and the shape of the crystal/melt interface during vertical Bridgman growth was studied. The position and the shape of the crystal/melt interface are a key factor for describing the final quality of growing crystal. Following two methods for characterization of its position and shape were used: (i) direct observation and (ii) direct temperature field measurement during simulated vertical Bridgman growth. As a model compound a lead chloride is used. Three different ampoule positions in two different temperature gradients in the furnace and two experimental arrangements – stationary (0 mm/h pulling rate) and dynamic (3 mm/h pulling rate) were analyzed. Obtained temperature data were projected as 2D planar cut under radial symmetry and denoted as isolevels. Their further conversion by linear approximation into isotherms allowed detail analysis of heat conditions in the system during simulated growth by comparison of isotherms 500 °C (m.p. of lead chloride) at different growth conditions.