Phase transition and soft phonon modes in SrZrO3 around 1200 degrees C by ultraviolet laser Raman spectroscopy

Raman spectra of SrZrO3 have been successfully obtained at temperatures fro m 600 degrees C to 1240 degrees C by using a new continuous-wave ultraviole t Raman spectroscopic system. The phase transition between cubic and tetrag onal phases is due to the collapse of the R-25 mode at the R point of the h igh-temperature cubic Brillouin zone. Two phonon modes observed to soften ( decrease) in frequency approach together and their peak intensities continu ously decreased with increasing temperature. They disappeared between 1200 degrees C and 1220 degrees C. The soft modes remain underdamped, the dampin g constant of soft modes increased with temperature toward phase-transition temperature satisfying the universal scaling law.