Low Temperature Infrared and Raman Spectra of Lithium Borohydride

Abstract

The infrared spectra of polycrystalline LiBH, and LiBD, have been recorded in the region 4000-50 cm-' at 80 OK. Raman spectra of polycrystalline samples were also recorded at this temperature. The spectra of the BH4-and BD,-lattice vibrations are consistent with symmetrically equivalent borohydride ions which lie on either general positions, two-fold axes or mirror-planes. Six lattice vibrations of translatory origin appear in the infrared spectrum of LiBH, and a mode of libratory origin is inferred from an absorption tentatively assigned as a second overtone of a librational mode.

Infrared and Raman Spectra of Single Crystals of Anhydrous Strontium Formate

“…Although this region of the spectrum was studied the expected first order absorptions did not appear. This is analogous to the case for both the NH: ions (9, 11) and BH; ions (6,12) where the expected librational frequencies appear only in the second and third order spectra.…”

Lattice anharmonicity and structural evolution of LiBH4: an insight from Raman and X-ray diffraction experiments

“…In this work, we present new Raman data as a function of temperature in conjunction with synchrotron diffraction data. These vibrational data are discussed in conjunction with previous vibrational studies on LiBH 4 [8][9][10][11], and correlated with structural response to temperature together with the phase diagram suggested before on the basis of symmetry analysis [7].…”

“…Figure 3 presents the Raman spectra in the bending mode region of LiBH 4 . In their early work, Harvey and McQuaker [8] assigned the weak band at ca 1254 cm À1 to the second overtone of a librational band. However, the theoretical vibrational frequencies [11,12] indicate clearly that this band is the third component of the symmetry-split 4 deformation mode.…”

“…The phonon modes in LiBH 4 and LiBD 4 have been studied before [8][9][10][11]. However, besides the very recent work by Racu et al [11], a detailed temperature evolution of Raman lines is still not documented.…”

Differential Scanning Calorimetry (DSC) and Synchrotron X-ray Diffraction Study of Unmilled and Milled LiBH4: A Partial Release of Hydrogen at Moderate Temperatures

“…The LiBH 4 crystal structure, phase transition, and phonons modes have been investigated, mainly by X-ray diffraction [11][12][13][14][15][16][17][18], Raman spectroscopy [15,[19][20][21][22][23], NMR [18,24,25], and calorimetry [18,26].…”