Single-crystal structure of pyrite-type HP-Pd0.84(1)Se2 prepared by high-pressure/high-temperature synthesis

摘要

At ambient conditions, PdSe2 dichalcogenides crystallize in the layered PdS2-type structure. If pressure is applied, the coordination number of palladium atoms increases and the three-dimensional pyrite-type structure with octahedral (PdSe6)(4-) coordination geometry is observed. For the first time, single crystals of a pyrite-type PdSe2 modification could be obtained and characterized, which were grown by multianvil high-pressure/high-temperature synthesis at 7.5 GPa and 1023 K. The crystals show the expected pyrite-type space group Pa (3) over bar (no. 205) and refinement results of a = 613.26(3) pm, R1 = 0.0233, and wR2 = 0.0247 (all data) were received for HP-Pd-0.84(1) Se-2. The single-crystal data revealed significant defect formation on the palladium site with 16% vacancies, which is in line with the orthorhombic PdX2-type high-pressure polymorphs HP-Pd0.94(1)S2 and HP-Pd-0.88(1) Se-2. The tendency of vacancy formation on the palladium site could also be verified by EDX measurements.