Fig. 1.

The crystallography of ARuO₃. (a) Schematic drawing of the three perovskites CaRuO₃, SrRuO₃, and BaRuO₃ where red balls stand for O, blue balls for Ru, and yellow balls for alkaline earth Ca, Sr, and Ba. (b) The crystal structures of the BaRuO₃ polytypes. Blocks of the face-shared and corner-shared RuO₆ octahedra are stacked alternately along the c axis. (c) X-ray powder diffraction spectra of the perovskites CaRuO₃, SrRuO₃, and BaRuO₃ and their best fit with the Rietveld analysis at room temperature.