Thallium Bromide crystals are grown by sealed-ampoule Stockbarger technique. Thallium salts are toxic, and Thallium Bromide has enough solubility to require extreme caution. Careful handling with plastic gloves covered with soft cotton gloves as appropriate to delicate optics is required.
(1) Handbook of Optical Constants, ed Palik, V3, ISBN 0-12-544423-0
(2) Arenberg, Measurements made at Naval Research Labs, USA 1948-49
(3) Kelly, Bureau of Mines Bulletin, No 371, p51. 1934