Resonance Raman spectroscopy of NdAlO3 single-crystal fibers grown by the laser-heated pedestal growth technique

摘要

NdAlO3 is a lanthanide monoaluminate compound presenting a trigonal structure with 'D POT. 6 IND. 3d' space group. Single crystal fibers of NdAlO3 were grown by the laser-heated pedestal growth (LHPG) technique. The cylindrical fibers grew parallel to [1 0 0] h direction without cracks or striations. At room temperature, the Raman spectra presented an enlarged number of the measured bands. Raman bands associated to the 'D POT. 6 IND. 3d' structure were compared with the prediction of lattice dynamic calculations performed using Wilson’s GF-matrix method. By using group-theory calculations, it was possible to suggest a reduction in crystal symmetry induced by the Nd/Al non-stoichiometric ratio. The 'C POT. 6 IND. 3v' and 'S POT. 2 IND. 6' phases are the best choices to describe the unit cell of our Al-deficient crystal fiber in place of 'D POT. 6 IND. 3d' phase.