The cubic perovskite BaRuO3 has been synthesized under 18 GPa at 1,000°C. Rietveld refinement indicates that the new compound has a stretched Ru-O bond. The cubic perovskite BaRuO3 remains metallic to 4 K and exhibits a ferromagnetic transition at Tc ‫؍‬ 60 K, which is significantly lower than the Tc Ϸ 160 K for SrRuO3. The availability of cubic perovskite BaRuO3 not only makes it possible to map out the evolution of magnetism in the whole series of ARuO3 (A ‫؍‬ Ca, Sr, Ba) as a function of the ionic size of the A-site rA, but also completes the polytypes of BaRuO3. Extension of the plot of Tc versus rA in perovskites ARuO3 (A ‫؍‬ Ca, Sr, Ba) shows that Tc does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO3. Suppressing Tc by Ca and Ba doping in SrRuO3 is distinguished by sharply different magnetic susceptibilities (T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO3 side and bandwidth broadening on the (Sr,Ba)RuO3 side.magnetism ͉ compounds ͉ Ruthenate

A thorough study has been made of the physical properties under high pressure of the perovskite BaRuO3 synthesized under pressure; it includes the critical behavior in the vicinity of Tc to 1 GPa and the temperature dependences of resistivity and ac magnetic susceptibility up to 8 GPa. The ferromagnetism in BaRuO3 is suppressed at 8 GPa. Critical fluctuations in the vicinity of Tc have been found in BaRuO3 and they are enhanced under pressure. These observations are in sharp contrast to SrRuO3 where mean-field behavior is found at Tc.

The [Formula: see text] sample with the nominal composition was synthesized. Powder X-ray diffraction (XRD) experiments confirm that it crystallizes in an orthorhombic structure with space group Immm. The synchrotron powder XRD results suggest that the crystal structure of [Formula: see text] keeps stable under pressure up to 34 GPa at room temperature with nearly isotropic compressibility. The equation of state for [Formula: see text] was obtained. The results offer opportunities to further synthesize and research [Formula: see text] superconductor with tetragonal [Formula: see text] structure.

The bismuth rhodate BiRhO 3 , which crystallizes in a perovskite structure, was synthesized under high-pressure and high-temperature conditions, using a 6-8 double stage multi-anvil apparatus. The synchrotron powder X-ray diffraction data suggest that the crystal structure of the BiRhO 3 perovskite is stable under pressures up to 34 GPa at room temperature with anisotropic compressibility. The equation of state for BiRhO 3 compound was obtained. The results offer opportunities for further research into the BiRhO 3 quantum compound with strong spin orbital coupling.