Structural and magnetic properties of high-pressure/high-temperature synthesized (Sr1–xRx)CoO3 (R=Y and Ho) perovskites

Polycrystalline perovskite cobalt oxides Sr1–xRxCoO3 (R=Y and Ho; image) were prepared by high-pressure/high-temperature technique. X-ray powder patterns of the Y-system indicated cubic perovskite form for image, and orthorhombic perovskite form for image and 1.0, while coexisting of the two phases for image. The cubic perovskite samples had metallic electric resistivities while the orthorhombic ones with semiconducting or insulating nature. The parent compound SrCoO3 showed a ferromagnetic transition at 266 K. With the Y substitution, the transition temperature increased slightly to ∼275 K at image, then decreased rapidly to ∼60 K for image. The YCoO3 (image) sample showed non-magnetic behavior. The Ho-substituted system showed quite similar structural, transport and magnetic properties to those of the Y-system.