Low-temperature Raman spectra of Sr0.66Ba0.34Nb2O6 single-crystal fibers

A possible structural change in Sr0.66Ba0.34Nb2O6 single-crystal fibers when the temperature decreases from 295 to 10 K was investigated by dielectric constant measurements and Raman spectroscopy. An anomaly observed in the dielectric constant and the loss factor is associated with the variation in the intensity and wavenumber of certain Raman modes. We observe that the relative intensity of low wavenumber modes has a singular behavior for the y(xz)(y) over bar scattering geometry. A high-wavenumber band disappears when the temperature is lowered to 10 K for the y(xz)(y) over bar geometry and shifts to higher wavenumber for the y(zz)(y) over bar geometry. These observations can be interpreted as evidence of a structural phase transition undergone by Sr0.66Ba0.34Nb2O6 single-crystal fibers at temperatures below 100 K. Copyright (C) 2003 John Wiley Sons, Ltd.