ChemInform Abstract: Synthesis, Structure, Magnetic and Photoelectric Properties of Ln₃M_0.5M′Se₇ (Ln: La, Ce, Sm; M: Fe, Mn; M′: Si, Ge) and La₃MnGaSe₇.

Abstract

Synthesis, Structure, Magnetic and Photoelectric Properties of Ln 3M0.5M'Se7 (Ln: La, Ce, Sm; M: Fe, Mn; M': Si, Ge) and La 3MnGaSe7. -The isostructural compounds La 3Fe0.5GeSe7 (I), La3MnGaSe7 (II), Ce3Fe0.5SiSe7 (III), Ce3Mn0.5SiSe7 (IV), Sm3Fe0.5SiSe7 (V), and Sm3Mn0.5GeSe7 (VI) are prepared by melting of the elements in a KI flux (C-coated evacuated silica tubes, 1273 K, 3 d). All the compounds crystallize with the Ce 6Al3.33S14-type structure (space group P63, Z = 2, single crystal XRD). The structure contains chains of face-sharing [MSe 6] octahedra and isolated [M'Se4] tetrahedra in the channels of a three-dimensional network of Ln and Se. Pure polycrystalline phases (III) and (IV) prepared by melting and annealing the elements without a flux show paramagnetic domination accompanied by antiferromagnetic contributions, while (V) and (VI) show anti-ferromagnetic phase transitions with Neel temperatures of 13 and 24 K, respectively. Most of the visible light is absorbed by compounds (III)-(VI) and the photocurrent densities are 81, 1.3, 1.8, and 0.8 A/cm 2 under 1 V of external voltage, respectively. -(HE, J.; WANG, Z.; ZHANG, X.; CHENG, Y.; GONG, Y.; LAI, X.; ZHENG, C.; LIN, J.; HUANG*, F.; RSC Adv. 5 (2015) 65, 52629-52635, http://dx.