Abstract. We report on the growth and initial thermal and optical characterisation of a single-crystalline ternary halide, Tl 4 CdI 6 . The crystal is described by the centrosymmetric tetragonal class P4/mnc at the room temperature. The parameters of linear thermal expansion are studied in the temperature region 330-500 K. The crystal is optically positive and reveals very high optical anisotropy (the birefringence ~ 0.13 at 633 nm). Its optical pseudo-gap value corresponds to widegap semiconductors. A broad maximum at 400-410 K found in the temperature dependence of IR radiation-induced second harmonic generation may be indication of a polymorphic phase transformation.
On the basis of dilatometric, optical, and dielectric investigations of (NH3C2H5)2CuC14 crystals the existence of phase transitions at T1 = 364 and T2 = 356 K was confirmed. Anomalous behaviour of the thermal expansion coefficient and optical birefringence around T3 = 330 K was related to earlier unknown phase transition. Besides, it was shown that these crystals are characterised by considerable protonic conductivity, the nature of which is fairly well explained in the framework of Grotthus mechanism of proton transport.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.