Syntheses, crystal structures and magnetic properties of two new chromium chalcogenides Cr(en)3SbSe4 and Cr(en)2AsSe3.

Abstract We report two new chromium chalcogenides Cr(en) 3 SbSe 4 and Cr(en) 2 AsSe 3 which were obtained by solvothermal reactions at 170 °C. Cr(en) 3 SbSe 4 adopts the tetragonal space group P 4 2 bc with isolated [Cr(en) 3 ]3+ ions and [SbSe 4 ]3− tetrahedrons. Cr(en) 2 AsSe 3 is a molecular crystal with the monoclinic space group P 2 1 / n. It has [Cr(en) 2 Se 2 ]− octahedrons and [AsSe 3 ]3− triangle cones which are edge shared by Se atoms. Cr(en) 3 SbSe 4 has a band gap of 2.3 eV, whereas Cr(en) 2 AsSe 3 displays multiple-absorption characters with two absorption edges at 1.7 and 2.2 eV, respectively. Remarkably, Cr(en) 3 SbSe 4 is a Curie-Weiss paramagnet between 2 and 300 K with an effective magnetic moment of 3.98 μ B , and is a potential magneto-caloric material with -Δ S m = 16.3 J (kg K)−1 at 4 K and Δ H = 8 T. Cr(en) 2 AsSe 3 shows antiferromagnetism below 9 K. Highlights • Two new compounds Cr(en) 3 SbSe 4 and Cr(en) 2 AsSe 3 were synthesized successfully by solvothermal methods. • Cr(en) 3 SbSe 4 is a potential magneto-caloric material, with Δ S m = 16.3 J (kg K)−1 at 4 K and Δ H = 8 T. • Cr(en) 2 AsSe 3 is a molecular crystal and displays antiferromagnetism below 9 K. [ABSTRACT FROM AUTHOR]