Effect of chloride substitution on the order–disorder transition in NaBH4 and Na11BD4

Olsen, Jørn Eirik; Karen, Pavel; Sørby, Magnus H.; Hauback, Bjørn C.

doi:10.1016/j.jallcom.2013.10.171

Cited by 13 publications

(17 citation statements)

References 18 publications

(23 reference statements)

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“…Moreover, low melting mixtures of complex hydrides have been studied recently as ionic liquids, aiming to provide fast and convenient re-fuelling of hydrogen in fuel cell vehicles. [19][20][21][22][23][24][25][26][27] Since the reported phase diagrams are not coherent and the experimental points are not fully described, further investigations are necessary. 13 Mixtures of metal borohydrides often show eutectic melting, e.g.…”

Section: Introductionmentioning

confidence: 99%

A thermodynamic investigation of the LiBH₄–NaBH₄ system

et al. 2016

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The LiBH 4 -NaBH 4 pseudo-binary system has been investigated by X-ray diffraction, temperatureprogrammed photographic analysis, and differential scanning calorimetry, in order to establish the phase diagram. The polymorphic orthorhombic-to-hexagonal phase transition of LiBH 4 was observed at 94 °C in samples containing NaBH 4 , i.e. 15 °C lower than for pure LiBH 4 , which indicates the dissolution of sodium into LiBH 4 . The formation of solid solutions was confirmed by powder X-ray diffraction measurements performed as a function of temperature. A new eutectic composition between Li 0.65 Na 0.35 BH 4 and Li 0.70 Na 0.30 BH 4 , with a melting temperature of 216 °C, is observed. Ab-initio calculations have been performed to establish the relative stabilities of the pure compounds in orthorhombic, hexagonal and cubic structure. The obtained experimental and calculated data were compared with available literature values and they were used for a thermodynamic assessment of the LiBH 4 -NaBH 4 system by the Calphad method. The enthalpy of mixing for solid and liquid solutions has been estimated on the basis of experimental data.The LiBH4-NaBH4 pseudo-binary system has been investigated by X-ray diffraction, temperature programmed photographic analysis and differential scanning calorimetry, in order to establish the phase diagram. Ab-initio calculations have been performed to establish the relative stabilities of the pure compounds in various structures. The obtained experimental and calculated data were compared with available literature values and they were used for a thermodynamic assessment of the LiBH4-NaBH4 system by the Calphad method.

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Section: Introductionmentioning

confidence: 99%

A thermodynamic investigation of the LiBH₄–NaBH₄ system

et al. 2016

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“…[179,180], no significant solubility in the orthorhombic and cubic phases is evidenced, while in the hexagonal phase limited solubility is detected at high temperatures. A solubility in the solid state is confirmed for many binary systems between borohydrides and metal halides: NaBH 4 -NaCl [174,177], NaBH 4 -NaBr [194], Ca (BH 4 ) closo-borane is observed [182,183,195,196].…”

Section: Solid Phasesmentioning

confidence: 82%

“…showing the formation of solid solutions, resulting from cationic [28,[170][171][172] or anionic [173][174][175][176][177][178][179][180][181] substitutions, as well as hydrogen-fluorine exchange [182][183][184][185]. For some binary and ternary mixtures of borohydrides, corresponding thermodynamic properties and phase diagrams have been recently assessed, allowing the determination of the enthalpy of mixing in solid and liquid phases [172,185].…”

Section: Solid Phasesmentioning

confidence: 99%

Complex hydrides for energy storage

Milanese

Jensen

Hauback

et al. 2019

International Journal of Hydrogen Energy

147

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In the past decades, complex hydrides and complex hydrides-based materials have been thoroughly investigated as materials for energy storage, owing to their very high gravimetric and volumetric hydrogen capacities and interesting cation and hydrogen diffusion properties. Concerning hydrogen storage, the main limitations of this class of materials are the high working temperatures and pressures, the low hydrogen absorption and desorption rates and the poor cycleability. In the past years, research in this field has been focused on understanding the sorption mechanism of the pristine and catalysed materials and on the characterization of the thermodynamic aspects, in order to rationally choose the composition and the stoichiometry of the systems in terms of hydrogen active phases and catalysts/destabilizing agents. Moreover, new materials have been discovered and characterized in an attempt to find systems with properties suitable for practical on-board and *Manuscript Click here to view linked References stationary applications. A significant part of this rich and productive activity has been performed by the research groups led by Experts of the International Energy Agreement Task 32, often in collaborative research projects. The most recent findings of these joint activities and other noteworthy recent results in the field are reported in this paper.

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“…This phase transition is accompanied by an order-of-magnitude decrease in the reorientational jump rate [5,25]. For Na(BH 4 ) 0.5 Cl 0.5 and Na(BH 4 ) 0.5 I 0.5 solid solutions, such a phase transition is suppressed [27]. Similar behavior was found for Li(BH 4 ) 1-x I x solid solutions, where the iodine substitution corresponding to x ≥ 0.33 suppresses the structural phase transition, stabilizing the high-T hexagonal phase down to low temperatures [7].…”

Section: Resultsmentioning

confidence: 97%

Effects of partial halide anion substitution on reorientational motion in NaBH4: A nuclear magnetic resonance study

Skoryunov

Babanova

Soloninin

et al. 2015

Journal of Alloys and Compounds

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To study the effects of partial halide anion substitution on the reorientational motion of [BH 4 ]anions in NaBH 4 , we have measured the 1 H and 11 B NMR spectra and spin-lattice relaxation rates in the cubic solid solutions Na(BH 4 ) 0.5 Cl 0.5 and Na(BH 4 ) 0.5 I 0.5 over broad ranges of temperature (8 -324 K) and the resonance frequency (14 -90 MHz). For both solid solutions, the measured 1 H spin-lattice relaxation rates are governed by reorientations of BH 4 groups, and the experimental data can be satisfactorily described by the model with a Gaussian distribution of the activation energies. The average values of the activation energies derived from the 1 H spin-lattice relaxation data are 192 ± 7 meV for Na(BH 4 ) 0.5 Cl 0.5 and 120 ± 3 meV for Na(BH 4 ) 0.5 I 0.5 . At a given temperature, the reorientational jump rates are found to increase in the order of Na(BH 4 ) 0.5 Cl 0.5 -NaBH 4 -Na(BH 4 ) 0.5 I 0.5 , in agreement with the quasielastic neutron scattering (QENS) results. This trend correlates with the lattice expansion reflecting the increase in the size of the corresponding anions (in the order of Cl --[BH 4 ] --I -).

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Effect of chloride substitution on the order–disorder transition in NaBH4 and Na11BD4

Cited by 13 publications

References 18 publications

A thermodynamic investigation of the LiBH₄–NaBH₄ system

A thermodynamic investigation of the LiBH₄–NaBH₄ system

Complex hydrides for energy storage

Effects of partial halide anion substitution on reorientational motion in NaBH4: A nuclear magnetic resonance study

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Effect of chloride substitution on the order–disorder transition in NaBH4 and Na11BD4

Cited by 13 publications

References 18 publications

A thermodynamic investigation of the LiBH4–NaBH4 system

A thermodynamic investigation of the LiBH4–NaBH4 system

Complex hydrides for energy storage

Effects of partial halide anion substitution on reorientational motion in NaBH4: A nuclear magnetic resonance study

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A thermodynamic investigation of the LiBH₄–NaBH₄ system

A thermodynamic investigation of the LiBH₄–NaBH₄ system