Abstract: Perovskite oxide SmCoO₃ was prepared by the high pressure and high temperature (HPHT) method. The structure and properties of the samples were investigated by XRD, Raman, electrical conductivity and thermal expansion measurement techniques. The results indicate that the raw materials Co₂O₃ and Sm₂O₃ can form SmCoO₃ under 2.75~4.20 GPa at about 1 060 ℃, but the reaction was not complete. The single phase SmCoO₃ was synthesized under the conditions of about 3.90 GPa and 1 061 ℃.The Raman spectra only shows the characteristic of orthogonal SmCoO₃. The single phase SmCoO₃ is an insulator under 327 ℃ and its electrical conductivity increases with temperature increasing, which shows an insulator-semiconductor-metal transition. The thermal expansion coefficient of the sample shows a linear change in a temperature range of 100~800 ℃, which is better than that of the sample prepared by solid-state reaction. 

Key words: SmCoO₃, high pressure and high temperature, solid state reaction, thermal expansion coefficient