Pressure Dependence of the Structural and Superconducting Properties of the Bi-Based Superconductor Bi₂Pd₃Se₂

The structural and superconducting properties of the Bi-based compound Bi₂Pd₃Se₂ were investigated over a wide pressure range. The prepared Bi₂Pd₃Se₂ sample was a superconductor with a superconducting transition temperature, T_c, of approximately 3.0 K, which differed from a previous report (T_c of less than 1.0 K). At ambient pressure, the powder X-ray diffraction (XRD) pattern of the Bi₂Pd₃Se₂ sample was consistent with that previously reported for Bi₂Pd₃Se₂. The Rietveld method was used to refine the crystal structure, which had a space group of C2/m (No. 12), as reported previously. This compound showed no clear anomaly due to the charge-density-wave (CDW) transition, as seen from the temperature dependence of magnetic susceptibility. However, the temperature dependence of electrical resistivity indicated a clear anomaly, presumably because of the CDW transition in the low-pressure range; the CDW transition temperature was approximately 230 K. The XRD patterns of the Bi₂Pd₃Se₂ sample were measured at 0.160-22.7 GPa, and the patterns were well analyzed by both the Le Bail and Rietveld refinement methods, showing no structural phase transitions in the above pressure range. The pressure dependence of T_c of Bi₂Pd₃Se₂ was recorded based on the temperature dependence of the electrical resistance, which showed an almost constant T_c at 0-13.7 GPa, and the T_c-pressure (p) behavior was fully discussed.