Growth, crystal structure, thermal properties and optical anisotropy of Tl4CdI6 single crystals

Abstract

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.

Novel Quaternary TlGaSn2Se6 Single Crystal as Promising Material for Laser Operated Infrared Nonlinear Optical Modulators

“…[54] that the substitution is possible because the ionic radii are nearly equal, 0.63 Å for Fe 3+ and 0.61 Å for Ga 3+ . Therefore, it may be assumed that the~790 nm peak (~1.57 eV) in the TlGaSn 2 Se 6 crystals is related to the statistical substitution of Ga 3+ (0.61 Å) ions with Sn 4+ ions (0.69 Å), which agrees with the data reported in [19,28].…”

“…Interesting results were also obtained by us in the study of several TlC III X VI 2 -based systems. For instance, the TlInSe 2 -D IV Se 2 systems (D IV = Si, Ge, Sn) [17,18] exhibit larger solid solution ranges of TlInSe 2 , the enhanced transport, and better photoelectric and non-linear optical parameters [19][20][21][22]. The fundamental difference of the TlInSe 2 -D IV Se 2 systems with respect to many other chalcogenide crystals is the presence of heavy Tl ions which determine the high polarization of the compounds.…”

“…At the same time, laser radiation causes irreversible changes that do not exceed 0.3%. Comprehensive studies of photoconductivity, particularly for thallium-bearing compounds, along with calculations of band structure, have shown an essential role of intrinsic cationic defects in the observed effects [19][20][21][22] with energy levels within the forbidden energy gap.…”

X-ray luminescence of Tl4CdI6 crystals

“…At now reports of an episodic character are being published in the periodical literature which deal with the possibility of obtaining one class of crystals of the А 4 ВХ 6 group (in particular, such as Tl 4 CdI 6 ) [1][2][3][4]) and studying their optical, mechanical and spectral characteristics [5][6][7][8][9]. It has been expected that along with the conservation of relatively high component of ionic bond the structural anisotropy should be large.…”

“…Crystal structure of Tl 4 CdI 6 In order to be sure of the purity and homogeneity of the grown bulk samples, the large single crystals were powdered.…”