High-Pressure Induced Structural Phase Transition in CaCrO4: Evidence   from Raman Scattering Studies
  Raman spectroscopic studies have been carried out on CaCrO4 under pressure up to 26GPa at ambient temperature. The Raman spectra showed CaCrO4 experienced a continuous structural phase transition started at near 6GPa, and finished at about 10GPa. It is found that the high-pressure phase could be quenched to ambient conditions. Pressure dependence of the Raman peaks suggested there existed four pressure regions related to different structural characters. We discussed these characters and inferred that the nonreversible structural transition in CaCrO4, most likely was from a zircon-type (I41/amd) ambient phase to a scheelite-type high pressure structure (I41/a). 
Y. W. Long, W. W. Zhang, L. X. Yang, Y. Yong, R. C. Yu, S. Ding, Y. L.   Liu, C. Q. Jin