Flux-Assisted Growth and Characterization of Noncentrosymmetric Quaternary Rare-Earth Selenides CsRESiSe4 (RE = La, Pr, Nd, Sm, Gd, Tb) Crystal Structure, Magnetism, and Theoretical Studies
来源：ACS Publications
A series of six cesium-containing rare-earth selenosilicates, CsLaSiSe4, CsPrSiSe4, CsNdSiSe4, CsSmSiSe4, CsGdSiSe4, and CsTbSiSe4, with the general formula CsRESiSe4 (RE = La, Pr, Nd, Sm, Gd, and Tb), have been successfully synthesized using a flux-assisted boron chalcogen mixture (BCM) method. Single-crystal X-ray diffraction analysis confirms that all compounds crystallize in the noncentrosymmetric orthorhombic space group P212121, adopting a layered structural framework with
[RESiSe4]− two-dimensional layers. The magnetic properties of CsPrSiSe4, CsNdSiSe4, CsSmSiSe4, and CsGdSiSe4 were investigated using polycrystalline powder samples. Temperature-dependent magnetic susceptibility measurements exhibit Curie–Weiss behavior across a wide temperature range, indicating predominantly paramagnetic interactions. The effective magnetic moments are determined to be 3.46, 3.61, 1.47, and 7.1 μB per formula unit for CsPrSiSe4, CsNdSiSe4, CsSmSiSe4, and CsGdSiSe4, respectively. Additionally, band gaps estimated from UV–vis spectroscopy are 2.7(1) eV for CsLaSiSe4, 2.5(1) eV for CsPrSiSe4, 2.4(1) eV for CsNdSiSe4, 2.0(1) eV for CsSmSiSe4, and 2.5(1) eV for CsGdSiSe4, confirming the semiconducting nature of these materials. The electronic structures were further investigated using first-principles density functional theory (DFT) calculations to provide deeper insight into their bonding and electronic properties.