RAMAN-SCATTERING STUDY OF CZOCHRALSKI-GROWN YTTRIUM FLUORIDE SINGLE-CRYSTALS

Single crystals of yttrium fluoride YF3 have been grown by the Czokral ski method and studied by Raman scattering in the temperature range 20 K - 730 K. The results are consistent with the prediction of the grou p theory analysis in the framework of the space group Pnma (7 Ag + 5 B 1g + 7 B2g + 5 B3g) although two lines B2g are missing.There is no evi dence for any structural phase transition in this temperature range. T he structural relationship between the phase investigated and the high temperature phase (out of the temperature range studied) is discussed .