Far-infrared and THz spectroscopy of 0.4PMN-0.3PSN-0.3PZN relaxor ferroelectric ceramics

摘要

Temperature dependenceof the opticphononsm0.4PbMg_(1/3)Nb_(2/3)O_3-0.3PbSc_(1/2)Nb_(1/2)O_3-0.3PbZn_(1/3)Nb_(2/3)O_3(0.4PMN-0.3PSN-0.3PZN) ceramics were studied by means of FTIR reflection and THz transmission spectroscopy in the temperature range of -253.15 to 226.85 deg C. On heating from low temperatures, the A_1 component of the strongly split TO_1 mode softens towards the Burns temperature, but the softening ceases near 126.85 deg C which could be a signature of polar cluster percolation temperature. Surprisingly, the TO_2 mode also softens on heating and follows the Cochran law with extrapolated critical temperature close to the melting point.