Effects of disorder on the Raman line-shape in ZrO_2
  Experimental data obtained by Lughi and Clarke [J. Am. Ceram. Soc., 88, 2552 (2005)] are compared to the theory describing disorder effects on optical phonons. Sharpening and vanishing of the asymmetry of the Raman lines after annealing are attributed to a decrease in short-range disorder. The parameters of disorder (such as the phonon-defect coupling and the correlation length) are defined in the comparison. 
L.A. Falkovsky