Single-crystal structure of pyrite-type HP-Pd₀.₈₄₍₁₎Se₂ prepared by high-pressure/ high-temperature synthesis
2018
Selb, Elisabeth | Tribus, Martina | Heymann, Gunter
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 Pa3̅ (no. 205) and refinement results of a=613.26(3) pm, R1=0.0233, and wR2=0.0247 (all data) were received for HP-Pd₀.₈₄₍₁₎Se₂. 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-Pd₀.₈₈₍₁₎Se₂. The tendency of vacancy formation on the palladium site could also be verified by EDX measurements.
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