Nine new rare earth magnesium-containing thiosilicates
of the formula
RE3Mg0.5SiS7 (Ln = Ce, Pr, Nd, Sm,
Gd, Tb, Dy, Ho, Er) were synthesized in an alkali halide flux using
the boron chalcogen mixture (BCM) method. Crystals of high quality
were produced, and their structures were determined by single-crystal
X-ray diffraction. The compounds crystallize in the hexagonal crystal
system in the P63 space group. Phase pure
powders of the compounds were used for magnetic susceptibility measurements
and for second-harmonic generation (SHG) measurements. Magnetic measurements
indicate that Ce3Mg0.5SiS7, Sm3Mg0.5SiS7, and Dy3Mg0.5SiS7 exhibit paramagnetic behavior with a negative
Weiss temperature over the 2–300 K temperature range. SHG measurements
of La3Mg0.5SiS7 demonstrated SHG
activity with an efficiency of 0.16 times the standard potassium dihydrogen
phosphate (KDP).