Polarized Raman spectra of LiBaB9O15 single crystal

We use polarized Raman spectroscopy to obtain the room temperature phonon modes of LiBaB9O15 single crystal, that crystallizes in a trigonal structure belonging to the space group R (3) over bar (D-3(d6)) with two molecules per primitive cell (Z(B)=2). The structure of the LiBaB9O15 crystal consists of a three-dimensional borate framework, formed by two BO3 triangles and one BO4 tetrahedra. Since BO3 and BO4 units share the oxygen atoms, we can not obtain a correlation scheme where their internal modes are distributed in terms of the irreducible representations of the D-3d factor group. The only modes that can unambiguously be assigned are the nu(3)(BO4) with Aig symmetry at 983 cm(-1) and the nu(1)(BO3) with E-g symmetry at 932 cm(-1). We observed 7A(1g)+6E(g) out of 11A(1g)+25E(g) vibrations predicted by the Group Theory. (C) 2015 Elsevier B.V. All rights reserved.