An investigation of the rare-earth telluride system BaLn2Te4 (Ln=Sm–Tm, Y): syntheses, crystal structures, and magnetic properties

Abstract

Single crystals of BaLn Te (Ln5Gd-Tm, Y) form as black needles from the stoichiometric reaction BaTe12Ln13Te at 10008C. 2 4 BaSm Te forms as a by-product in the reaction BaTe1Sm1Zn1Te at 8508C with the aid of a BaBr / KBr flux. The compounds 2 4 2 16 crystallize with four formula units in the space group D -Pnma (No. 62) in the CaFe O (calcium ferrite) structure type. Unit cell 2h 2 4˚˚constants range from a513.6883(10) A, b54.5148(3) A, and c516.3427(12) A in the Sm compound to a513.5677(10) A, b54.4058(3)Å , and c515.9989(12) A for Tm (t521208C). Ln atoms are coordinated by six Te atoms in an octahedral arrangement. These octahedra share corners and edges to form a three-dimensional channel structure. Ba atoms occupy the bicapped trigonal-prismatic sites within these channels. Magnetic susceptibility data for two representative compounds (Ln5Er and Tb) show paramagnetic behavior in the region 5-300 K.

Thermoelectric properties of the new tellurides SrSc2Te4 and BaSc2Te4 in comparison to BaY2Te4

“…The distortions of the octahedra further confirm the trends outlined by Ibers et al for the BaLn 2 Te 4 series (Ln ¼ Y, SmeTm) [13]. The first trend is that the distortion of the M1Te 6 octahedra increases slightly with decreasing M size.…”

“…We refined the structures commencing from the published atomic positions of BaY 2 Te 4 [13]. The refinements went smoothly and converged with residual factors of wR 2 ¼ 0.090 for SrSc 2 Te 4 and of wR 2 ¼ 0.097 for BaSc 2 Te 4 (all data).…”

“…Ba substituted variants of La 3 S 4 in the Th 3 P 4 type were studied as well [11,12]. Recently, Ibers et al presented the crystal structures and magnetic properties of the series BaM 2 Te 4 (with M ¼ Y, SmeTm), crystallizing in the calcium ferrite type, CaFe 2 O 4 [13].…”

Single Crystals of the Isotypic Series BaLu2Ch4 (Ch = S, Se and Te) with CaFe2O4-Type Structure

“…Instead of the target compounds several ternary chalcogenides with the formula type BaLn 2 Ch 4 (Ln = Gd, Tb, Er, Tm, Lu; Ch = S, Se and Te) could be isolated and identified by X-ray single crystal and powder diffraction after washing the products with water. Although the first attempts to synthesize almost all of the compounds BaLn 2 Ch 4 were successful and described by Bugaris and Ibers [27] and Narducci et al [28], the lutetium representatives were not described in their papers. Table 1 for atomic coordinates).…”

“…Although several examples for lutetium-bearing chalcogenides were characterized, the combination of barium as divalent (Ba [24]. Furthermore, besides BaY 2 S 4 [25] and the defective crystal structure of Ba 0.9 Sm 2 S 3.9 [26] no other examples for sulfide-containing compounds with barium and rare-earth metal cations are known with the CaFe 2 O 4 -type arrangement hitherto, while many representatives for the compositions BaLn 2 Se 4 [27] and BaLn 2 Te 4 [28] could be synthesized. In this short paper the crystal structures of the three isotypic barium lutetium chalcogenides BaLu 2 Ch 4 (Ch = S, Se and Te) will be presented and discussed.…”