Mapping trends in the reorientational mobilities of tetrahydroborate anions via neutron-scattering fixed-window scans

Probing the unusual anion mobility of LiBH4 confined in highly ordered nanoporous carbon frameworks via solid state NMR and quasielastic neutron scattering

“…It is clear that the onset occurs near 50 K for the conned LiBH 4 , about 100 K lower than for the bulk (near 150 K), in agreement with observations in NMR and consistent with the FWS behavior of BH 4 À anions observed for LiBH 4 in 13 nm carbon aerogels. 41 Furthermore, the onset of BH 4 À rotational dynamics in the NPC is more gradual than in the bulk, suggesting an inhomogeneity (broad distribution) in the BH 4 À rotational potentials for the former. Consistent with NMR observations of two translationally distinct BH 4 À populations in LiBH 4 @NPC-4 nm, analysis of QENS spectra reveal two reorientationally distinct populations of BH 4 À anions.…”

“…Shane reorientational mobilities compared to the bulk, especially for partially lled aerogels. 41 Verkuijlen et al also studied structural and dynamical properties of LiBH 4 conned in a porous graphitic carbon and ordered porous silica by solid state NMR.…”

Di-hydrogen contact induced lattice instabilities and structural dynamics in complex hydride perovskites

“…B-H vibrations are readily studied by vibrational spectroscopy while the much lower energy transfers of stochastic reorientations are investigated by means of quasi-elastic neutron scattering. The structural dynamics of monometallic borohydrides have been extensively investigated by vibrational spectroscopy [28][29][30], solid state NMR spectroscopy [31][32][33][34][35], inelastic x-ray scattering IXS [36], inelastic neutron scattering INS [37], QENS [38][39][40] and recently by molecular dynamics assisted density functional theory (MD-DFT) [41,42]. The importance of the vibrational density of states for the stabilities of different polymorphs has also been discussed [43].…”

A quasielastic and inelastic neutron scattering study of the alkaline and alkaline-earth borohydrides LiBH4 and Mg(BH4)2 and the mixture LiBH4 + Mg(BH4)2

“…In the alkaline borohydrides LiBH 4 , NaBH 4 and KBH 4 , the crystal phase transition is accompanied by a change of the local rotational reorientation of the [BH 4 ] (order-disorder transition), moreover changes in the external [BH 4 ]-vibrational modes have been measured using inelastic neutron spectroscopy (INS). [19][20][21][22] INS has also been used to measure the low energy excitation spectra of aand b-Ca(BH 4 ) 2 , showing that the two polymorphs differ in the vibrational frequency of the [BH 4 ] tetrahedra. 23 Measurements of the low energy transfer dynamics in these compounds are thus essential to understand the stability and binding in the borohydride compounds.…”