Cation Substitution Effects in the System Sr<sub>2−<i>x</i></sub>Ba<i><sub>x</sub></i>Bi<sub>3</sub> (0 ≤ <i>x</i> ≤ 1.3): Structural Distortions Induced by Chemical Pressure KimSung-Jin PonouSimeon FässlerThomas F. 2008 Crystals of the composition Sr<sub>2-<i>x</i></sub>Ba<sub><i>x</i></sub>Bi<sub>3</sub> (0 ≤ <i>x</i> ≤ 1.3) have been synthesized from the elements and were characterized by single-crystal and powder X-ray diffraction methods. The compounds crystallize for <i>x</i> = 0, 0.45, 0.86, 1.08, 1.28 in the structure type of the parent compound Sr<sub>2</sub>Bi<sub>3</sub> with space group <i>Pnna</i> (No. 52) and <i>Z</i> = 4. Substitution of Sr by Ba leads to a site preference for Ba. The anionic Bi substructures in the pseudoternary system simultaneously distort under remarkable elongation of one distinct Bi−Bi contact. Magnetic measurements for samples with <i>x</i> = 0, 0.45 and 1.08 reveal superconducting transitions at low temperatures. Linear muffin-tin orbital band structure calculations of Sr<sub>2</sub>Bi<sub>3</sub> show strong cation–anion interactions that greatly stabilize the structure. Besides showing characteristics of a typical metal, the band structure plot unveils the coinstantaneous occurrence of flat and steep bands around the Fermi level indicative for superconductivity.