Lattice vibrations and thermal conductance of Li2O(B2O3)3 crystals

Li2O·3B2O3 or Li2O(B2O3)3 (LOBO) crystallizes in the orthorhombic space group Pna21 with cell parameters a = 0.73788(6), b = 0.84473(7) and c = 0.51395(5) nm and two formula units in the primitive cell. Raman results show that the characteristic spectra of LOBO are mainly contributed by particularly the B(3)—O tetrahedra and also the B(1)—O and B(2)—O triangles and partly ascribed to the breathing vibrations of the B—O rings. The structural rigidity of LOBO is associated with all B—O bond stretching and bending of especially the B(3)—O bonds. The excellent non-linear optical properties of LOBO are mainly attributed to the more anionic groups in the primitive cell and their deviations from the Td or D3h symmetry. The short ultraviolet absorption edge is mainly attributable to the tilt of the B—O rings. The lattice thermal vibrations show that the anisotropically thermal conductivity is outstanding especially along the c direction. Copyright © 2004 John Wiley & Sons, Ltd.