CRYSTAL STRUCTURE AND VIBRATIONAL SPECTRA OF Li2BAlO4

摘要

The structure of Li2BAlO4 is solved ab initio by a powder XRD technique. The unit cell of this metaboroaluminate compound is monoclinic (space group P21/c, a=6.2720(3) angstroms, b=5.0701(3) angstroms, c=10.2989(6) angstroms, beta=95.882(2) degrees, Z=4, rho calc=2.36 g/cm3). Its network consists of infinite chains of metaaluminate tetrahedra, which are cross-linked by metaborate triangles in a way that leads to the formation of B2Al2O4 8 rings. These anionic groups are charge-balanced by two crystallographically distinct pairs of four-coordinated Li ions. The infrared and Raman spectra Li2nBAlO4 and Li210BAlO4 are reported, and the assignments of their main features are discussed in light of the spectra of relevant compounds. Vibrational spectroscopic tools for the identification of mixed metaboroaluminate network sequences are proposed. 21 refs.