Crystal Growth of Quaternary Rare Earth Selenosilicates by Using the Flux-Assisted Boron Chalcogen Mixture Method: Investigation of Their Magnetic and Optical Properties
来源：ACS Publications
A series of rare earth magnesium selenosilicates, RE3Mg0.5SiSe7 (RE = Ce, Pr, Nd, Sm, Gd, Tb, Dy) were obtained as single crystal using the flux assisted boron chalcogen mixture (BCM) method. The structures of the crystals were determined by single-crystal X-ray diffraction. The RE3Mg0.5SiSe7 series crystallizes in the hexagonal crystal system in the space group P63. Polycrystalline powders were synthesized to perform physical property measurements. Magnetic measurements over the 2–300 K temperature range reveal that Ce3Mg0.5SiSe7 and Gd3Mg0.5SiSe7 exhibit paramagnetic behavior with negative Weiss constants (θW = −14.50, θW = −6.13 K, respectively). The optical properties of RE3Mg0.5SiSe7 (RE = Ce, Pr, Nd, Sm, Gd) were measured by ultraviolet–visible (UV–vis) diffuse reflectance. Density functional theory (DFT) electronic structure calculations were performed. A second harmonic generation measurement was performed on a polycrystalline powder of Ce3Mg0.5SiSe7 and was found to be SHG active with an efficiency of 0.11 times the standard potassium dihydrogen phosphate (KDP).
In our exploration, we decided to take advantage of the combined BCM and molten flux methods to target single crystals of the RE3Mg0.5SiSe7 (RE = Ce, Pr, Nd, Sm, Gd, Tb, Dy) series to enable structure determination, while the combined BCM method and solid state synthesis route was used to obtain polycrystalline samples for property measurements. Herein, we discuss the synthetic approach for obtaining high-quality single crystals of RE3Mg0.5SiSe7 (RE = Ce, Pr, Nd, Sm, Gd, Tb, Dy) along with their crystal structure determinations, and furthermore, we report on our investigation of the magnetic properties of RE3Mg0.5SiSe7 (RE = Ce, Gd), and the SHG properties of Ce3Mg0.5SiSe7 compounds within this series.