Crystal structure of the Tl4GeSe4 ternary compound

Abstract

The crystal structure of the Tl 4 GeSe 4 compound was determined by X-ray single crystal diffraction. The title compound crystallizes with the Tl 4 SiSe 4 structure type (space group C2/c). The Tl + cations are coordinated by four separate [GeSe 4 ] 4anions, whereas the [GeSe 4 ] 4anion is surrounded by nine Tl + cations. Strengthening of the cation-anion interactions was observed with respect to the Si-compound.

The Tl2Se–HgSe–GeSe2 system and the crystal structure of Tl2HgGeSe4

“…The interatomic distances Hg-Se are close to those in Hg 4 SiSe 6 (0.2501-0.2932 nm) [34] or Hg 2 SnSe 4 (0.2636-0.2720 nm) [35]. The Ge-Se distances correlate well with those in Tl 4 GeSe 4 (0.250-0.256 nm) [24], Tl 2 GeSe 3 (0.229-0.260 nm) [25], and Tl 2 Ge 2 Se 5 (0.234-0.258 nm) [23].…”

“…Three compounds were found in the Tl 2 Se-GeSe 2 system: Tl 4 GeSe 4 and Tl 2 GeSe 3 melt congruently at 661 and 706 K, respectively, with Tl 2 GeSe 3 melting at the transition point; Tl 2 Ge 2 Se 5 melts incongruently at 778 K [22]. Tl 4 GeSe 4 has a monoclinic structure (space group C2/c, а = 1.16700(2) nm, b = 0.73170(1) nm, с = 2.56030(10) nm, β = 106.54(1)º) [23]. Tl 2 GeSe 3 crystallizes in a triclinic structure (space group P-1) with the unit cell parameters а = 1.5602 nm, b = 1.5549(5) nm, с = 0.9052(3) nm, α = 90.55(7)º, β = 111.42(6)º, γ = 114.45(7)º [24].…”