Raman and infrared spectra of Nd-doped barium sodium niobate crystals

Neodymium-modified barium sodium niobate (Ba2Na)(1-x)NdxNb5O15 (BNN:Nd), wi th x = 0.025 crystallizes with a filled tungsten bronze (TB) type structure in the tetragonal system, conforming to the space group P4bm and Z = 2. Th e lattice constants are a = 1.2446(1) and c = 0.3991(1) nm at room temperat ure. T-c = 537 +/- 2 degrees C, The experiments show that the Nd-ions effec tively improve crystal structural quality. The lattice vibrational spectrum , studied by Raman and infrared reflectivity spectroscopy, shows that the c rystal microscopic structure and lattice dynamics, thereby the microstrain and microstress, are very stable in a temperature range from 22 to approach ing 500 degrees C.