Investigations on the solid state interaction between LiAlH4 and NaNH2

Article abstract of DOI:10.1016/j.jssc.2010.07.014

In this paper, two LiAlH₄NaNH₂ samples with LiAlH₄ to NaNH₂ molar ratio of 1/2 and 2/1 were investigated, respectively. It was observed that both samples evolved 2 equiv H₂ in the ball milling process

Full text of DOI:10.1016/j.jssc.2010.07.014

Journal of Solid State Chemistry 183 (2010) 2040–2044
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Journal of Solid State Chemistry
journal homepage: www.elsevier.com/locate/jssc
Investigations on the solid state interaction between LiAlH4 and NaNH2
Yong Shen Chua b, Guotao Wu a, Zhitao Xiong a,n, Ping Chen a,b
a Dalian Institute of Chemical Physics, Dalian 116023, China
b Department of Chemistry, National University of Singapore, Singapore 117542, Singapore
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper, two LiAlH4–NaNH2 samples with LiAlH4 to NaNH2 molar ratio of 1/2 and 2/1 were
investigated, respectively. It was observed that both samples evolved 2 equiv H2 in the ball milling
process, however, the reaction pathways were different. For the LiAlH4–NaNH2 (1/2) sample,
Li3Na(NH2)4 and NaAlH4 were formed through cation exchange between reactants. The NaAlH4 formed
further reacts with Li3Na(NH2)4 and NaNH2 to give H2, NaH and LiAlN2H2. For the LiAlH4–NaNH2 (2/1)
sample, Li3Na(NH2)4, LiNH2 and NaAlH4 were formed firstly through the same cation exchange process.
The resulting LiNH2 reacts with the remaining LiAlH4 and produces H2 and Li2AlNH2.
& 2010 Elsevier Inc. All rights reserved.
Received 11 March 2010
Received in revised form
23 June 2010
Accepted 12 July 2010
Available online 15 July 2010
Keywords:
Hydrogen storage
Cation exchange
NaAlH4
LiNH2
1. Introduction
electron-rich hydrogen atoms, [AlH4]À anion in LiAlH4 will act as
hydride source. Several authors recently focused on interactions
between Li(Na)NH2 and Li(Na)AlH4 at varied molar ratios, with the
hope to obtain a reversible system. Xiong et al. investigated LiNH2–
LiAlH4 (1/1) [13] and (2/1) [14] system and reported that the formal
system is able to detach 8 wt% of H2, but none of those H2 can be
recharged under 80 bars of H2 pressure. LiNH2–LiAlH4 (2/1) system
on the other hand is able to detach 2 equiv H2 after 12 hours of ball
milling to form a Li–Al–N–H complex which can reversibly store
5.17 wt% of H2. Relevant work was done by Nakamori et al. [15] in
the LiNH2–LiAlH4 (2/1) system. In the study of LiNH2–LiAlH4 (1/2)
system Jun and Fang [16] reported that LiNH2 functions as a
destablizer, like other catalysts i.e. TiCl3–1/3AlCl3 which effectively
promotes the decomposition of LiAlH4. Other combination of
amides-complex hydrides, i.e., LiNH2–LiAlH4, LiNH2–NaAlH4,
NaNH2–LiAlH4 and NaNH2–NaAlH4, were also studied by Dolotko
et al. [17].
Among a wide range of amides–complex hydrides combina-
tions, interaction between NaNH2 and LiAlH4 is of particular
interest. Our previous investigations on LiAlH4–NaNH2 system
(LiAlH4–NaNH2 molar ratio 1/1) revealed that 2 equiv H2 or 5.2 wt%
hydrogen can be evolved upon mechanical milling or heating these
two chemicals at ca. 120 1C [9]. The evolution was a strong
exothermic reaction and as a result, reversibly storing hydrogen on
this system was not thermodynamically favored. However, the rate
of hydrogen release is remarkably faster than most of the complex
and chemical hydrides. In this study, we varied the molar ratio of
LiAlH4/NaNH2 to 1/2 and 2/1 in hope that compositional change in
the starting mixture will lead to a different reaction pathway and
thus alter the thermodynamics and kinetics of hydrogen evolution.
Our experimental results showed that a total of 2 equiv H2 can be
The depletion of fossil fuel has aroused tremendous efforts in
building a new energy system. Because of its abundance, high
energy output and zero emission hydrogen is recognized as the most
prospective energy carrier in the future energy system. A typical
hydrogen cycle is composed of hydrogen production, hydrogen
delivery and the conversion of hydrogen to electricity or thermal
energy. Pipeline can be used to supply hydrogen to stationary users,
while for mobile application, hydrogen has to be stored on-board.
Hydrogen storage is one of the key technological challenges in
building an efficient, hydrogen-powered fuel cell vehicle. Several
potential storage systems such as complex hydrides [1,2], metal
organics frameworks (MOFs) [3,4], ammonia borane [5,6] and so
forth, have been developed recently to meet the gravimetric and
volumetric density requirements. One of the prospective solid
storage systems is the amide–hydride combination which was
brought out based on the discovery of hydrogenation of Li3N [7].
Various combinations of amides and hydrides were found capable of
evolving hydrogen at temperatures lower than those for the thermal
decomposition of amide and hydride individuals [8–11]. Driving
force for the solid state amide–hydride interaction was mainly
d
+
attributed to high potential for the combination of H in amide and
d
À
H
in hydride [12]. In addition, the attraction between N in amide
and cation in hydride was also considered responsible for the
occurrence of interaction [12]. Very recently, complex hydrides
e.g. LiAlH4 were brought into amide–hydride system. Owing to its
n Corresponding author. Fax: +86 84685940.
E-mail address: xzt@dicp.ac.cn (Z. Xiong).
0022-4596/$ - see front matter & 2010 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2010.07.014

Y.S. Chua et al. / Journal of Solid State Chemistry 183 (2010) 2040–2044
2041
released from the two LiAlH4/NaNH2 mixtures in the process of ball
milling. The reaction pathways were uncovered as a result of
detailed XRD, FTIR and NMR characterizations on those species
formed in the milling process. It was observed that LiAlH4 and
NaNH2 firstly underwent cation exchange to form intermediates
prior to dehydrogenation. At the end of dehydrogenation (upon
releasing 2 equiv H2) two complexes, i.e., LiAlN2H2 (1/2 ratio) and
Li2AlNH2 (2/1 ratio), were formed.
2. Experimental methods
2.1. Sample preparations
LiAlH4 and NaNH2 were Fluka products with claimed
purities of 97% and 95%, respectively, and were used as received.
LiAlH4–NaNH2 mixtures with LiAlH4/NaNH2 molar ratio 1/2 and
2/1 (denoted as S-I and S-II) were mechanically milled on a Retsch
PM 400 mill at 200 rpm. The ball to sample ratio was about 30:1.
At the milling interval, the milling vessel was connected to a
pressure gauge to measure the gas pressure inside. Gaseous
product was also conducted to a mass spectrometer (MS) for
analysis and in all case only hydrogen was detectable. For
comparison, LiAlH4 was milled alone at same conditions for up
to 50 hours and negligible amount of hydrogen was evolved, in
consistent with the literature reports [18,19]. NaNH2 is stable too
against ball milling. All the sample handlings were carried out
within a MBRAUN glove-box which was filled with purified argon
to prevent air and moisture contaminations.
Fig. 1. Time dependences of hydrogen evolution from S-I and S-II sample in the
ball milling process.
reaction between LiAlH4 and NaNH2. MS analysis revealed that
hydrogen was the only detectable gaseous product. Therefore, by
applying the ideal gas equation the amount of hydrogen evolved
can be measured quantitatively. Ball milling the S-I sample for 46
hours resulted in the evolution of ca. 3.9 equiv H atoms, while S-II
sample released the same amount of H2 in just 14 hours of ball
milling. Such difference in the reaction rate hints that changing
the LiAlH4/NaNH2 molar ratio in the starting mixture should
induce different reaction pathway. By taking into account of
the purities of starting chemicals, 2 equiv H2 were evolved
from the above two samples, identical to that evolved from the
LiAlH4/NaNH2 (1/1) sample. It is important to note that LiAlH4
alone cannot decompose to give off H2 under the identical ball
milling conditions, therefore, an interaction between NaNH2 and
LiAlH4 should take place leading to the evolution of hydrogen.
To obtain more details on the mechanism of hydrogen
evolution from the S-I and S-II samples the milling process was
intentionally terminated at several milling intervals, i.e., stages 1,
2, 3 and 4 correspond to the milling intervals where ca. 1, 2, 3 and
2.2. Sample characterizations
To understand the mechanism for hydrogen evolution from the
LiAlH4–NaNH2 system, samples collected at different ball milling
intervals were characterized by Fourier transform infrared (FTIR),
X-ray diffraction (XRD) and solid state nuclear magnetic resonance
(NMR). FTIR spectra were recorded by a Perkin-Elmer 3000 FTIR
spectrometer at room temperature. Diffuse reflectance IR Fourier
transform (DRIFT) mode was applied. Structural identifications
were performed by using a Bruker D8 advanced diffractometer
equipped with an in situ cell. XRD data were collected from 101 to 601
with a scan-step width of 0.011 using CuKa radiation. Sample in
pellet was placed on platinum holder and occasionally diffraction
peaks of platinum were observed. Chemical shifts for 27Al, 23Na
and 7Li nuclei were recorded on a DRX400 Bruker spectrometer by
referring to 1.0 M of aluminum nitrate Al(NO3)3, sodium chloride
(NaCl) and lithium chloride (LiCl) aqueous solutions. Samples
were packed in 4 mm magic-angle spinning (MAS) zirconia rotors
with a Kel-F cap inside the glovebox. NMR spectra were acquired
in a cross-polarization (CP)/MAS probe using single-pulse excita-
tion and a rotor-spinning rate of 10 kHz. The post-milled samples
were subject to temperature programmed desorption (TPD) and
differential scanning calorimeter (DSC) measurements. Briefly,
samples of ca. 50 mg was loaded onto the homemade TPD system
and heated at a ramping rate 2 1C/min. Purified argon was used as
carrier gas to bring the gaseous products to a MS where mass
channels of H2, NH3, N2 and water were monitored. ca. 10 mg
samples were tested in a Netzsch DSC 204 HP unit. Sample was
heated at 2 1C/min in argon flow.
4
equiv H atoms were evolved, respectively. The milling
intermediates were then collected and subjected to FTIR, XRD
and solid NMR characterizations. LiAlH4 and NaNH2 were also
mixed simply by mortar and pestle and the resulting mixture was
investigated for comparison. As shown in Fig. 2 S-I sample at stage
1 displayed characteristic N–H stretches of NaNH2 and two other
absorbances at 3294 and 3240 cmÀ1 which were assigned to the
N–H stretches of ternary amide, Li3Na(NH2)4 [20]. In the case of
S-II sample, Li3Na(NH2)4 was also observed at initial milling stage
but it were consumed rapidly. NaNH2 in S-II was totally
disappeared at the stage
1 while N–H stretches of LiNH2
emerged. XRD characterizations (Figs. 3 and 4) at the stage 1
revealed the appearance of NaAlH4 in both samples. Summarizing
FTIR and XRD results a stoichiometric ionic exchange would
therefore appear as Eq. (1)
LiAlH4+NaNH2-LiNH2+NaAlH4
(1)
With standard enthalpy of formation of each reactant the enthalpy
change of reaction (1) was calculated to be À54.9 kJ/mol, an
exothermic reaction that is thermodynamically allowed at ambient
milling condition. The formation of Li3Na(NH2)4 should be the
result of further reaction of LiNH2 with NaNH2, as shown in Eq. (2)
3. Results and discussion
The time dependence of pressure risings inside the milling
vessel were monitored for the S-I and S-II samples. As shown in
Fig. 1 gas was evolved gradually with the progress of solid-state
2+3LiNH2-Li3Na(NH2)4
NaNH
(2)

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Y.S. Chua et al. / Journal of Solid State Chemistry 183 (2010) 2040–2044
To verify this, a LiNH2ÀNaNH2 mixture of LiNH2/NaNH2 molar
ratio of 3/1 was ball milled under the same conditions and it was
found that following the vanishment of N–H stretches of NaNH2
and LiNH2 those absorbances at 3294 and 3240 cmÀ1 appeared,
evidencing the formation of Li3Na(NH2)4. Although the thermo-
dynamic parameter of Li3Na(NH2)4 is unknown, the overall Gibbs
free energy change for the reaction (2) should be negative.
However, XRD characterization could not present distinct pattern
of this ternary amide indicating that this material can be easily
deformed upon mechanical ball milling. Eq. (3) was obtained after
combining Eqs. (1) and (2)
3LiAlH4+4NaNH2-3NaAlH4+Li3Na(NH2)4
(3)
Therefore, with the understanding that N–H stretches of NaNH2
and Li3Na(NH2)4 are detected in S-I sample where NaNH2 is
excessive, while in the S-II N–H stretches of LiNH2, instead of
NaNH2, is observed the reaction processes at the early stage of ball
milling S-I and S-II samples can be expressed by Eqs. (4) and (5),
respectively.
Fig. 2. FTIR spectra of S-I and S-II samples collected at different milling stages.
# represents the N–H absorbances in Li3Na(NH2)4, % LiNH2, o NaNH2.
S-I LiAlH4+2NaNH2-NaAlH4+1/3Li3Na(NH2)4+2/3NaNH2
(4)
(5)
S-II 2LiAlH4+NaNH2-3/4NaAlH4+1/4Li3Na(NH2)4+5/4LiAlH4
-LiNH2+LiAlH4+NaAlH4
With the progress of ball milling more hydrogen was evolved, the
IR bands of Li3Na(NH2)4 and NaNH2 were getting weakened and
eventually disappeared in both S-I and S-II systems. LiNH2
emerged in the S-II and then disappeared too. A broad band in
the range 3200–3350 cmÀ1 was developed in the post-milled S-I
sample, indicating the formation of an imide-like compound
[11,21]. From the XRD characterizations it is interesting to see
that along with the progress of hydrogen evolution NaAlH4 in the
S-I sample and LiAlH4 in the S-II sample were gradually
consumed. Their degradation products, Na3AlH6 and Li3AlH6,
were observed obviously in the mid of dehydrogenation process.
At the final stage no more hydrogen was evolved in the milling
process NaH was the only detectable phase in the S-I sample;
while no distinct phase can be identified in the S-II sample. A
broadband is presented in the range 20–501, indicating the
existence of amorphous structures (see Figs. 3 and 4) in the
sample.
Fig. 3. XRD patterns of S-I sample collected at different milling stages.
Solid state magic angle spinning NMR (MAS NMR) was then
employed to detect the changes in chemical environment of 23Al,
23Na and 7Li nuclei in the milling process. Shown in Fig. 5 is the
27Al NMR spectrum. It can be seen that at the stage 2 both S-I and
S-II samples displayed a peak at around À43.6 ppm and a broad
resonance in the region of 80–120 ppm. The former resonance
was assigned to Al in [AlH6] [3,22] evidencing the formation of
Na3AlH6 (in S-I system) and Li3AlH6 (in S-II system) which are in
good agreement with the XRD observations. Through curve fitting
the broad resonance in the region of 80–120 ppm is composed of
two overlapping sites centralizing at ca. 95 and 108 ppm,
respectively. The resonance at ca. 95 ppm was assigned to the
Al in [AlH4]À (can be LiAlH4 [22] or NaAlH4 [23]). The resonance
at 108 ppm is at a position between the chemical shift of
Al in AlN4 (112 ppm) [14,24] and Al in [AlH4]À, suggesting
that Al may exist in a coordinated environment of [AlH4ÀxNx].
Similar assignment was given in previous investigations on the
LiAlH4–LiNH2 system [14]. The appearance of [AlH4ÀxNx] site
announces the formation of chemical bonding between Al and N.
As prolonging the ball milling [AlH6]3À resonance was gradually
disappeared. The majority of Al species at the end of ball milling
was [AlH4ÀxNx] for the S-I sample and a mixture of [AlH4]À and
[AlH4ÀxNx] for the S-II sample. 23Na NMR spectra showed that the
Fig. 4. XRD patterns of S-II sample collected at different milling stages. Platinum
sample holder was observed occasionally.

Y.S. Chua et al. / Journal of Solid State Chemistry 183 (2010) 2040–2044
2043
Fig. 5. Solid 27Al, 23Na and 7Li NMR spectra of S-I and S-II samples collected at milling stage 2 and 4.
Na species in S-I sample were NaH and NaAlH4 at the stage 2 and
NaH at the stage 4, respectively. For the S-II sample, only Na in
NaAlH4 was detectable in both 2 and 4 stages. The disappearance
of NaAlH4 from the XRD characterization (at the stage 4) is
probably due to the energetic ball milling which destruct the
crystal into an amorphous state. In this context, [AlH4ÀxNx] anion
should bond with Li in both S-I and S-II samples. Accordingly, the
chemical shift for 7Li in the stage 4 was found around 2.21 ppm in
S-I sample and 0.57 ppm in the S-II, which are different from each
other and from that of LiNH2 (2.38 ppm).
On the basis of FTIR, XRD and solid state NMR characterization
results, conclusion on the solid state reaction between NaNH2 and
LiAlH4 in the S-I and S-II samples can be drawn. Scheme 1
summarizes the chemical processes taking place in both systems.
In the S-I, the chemical environment of Na changes from NaNH2 to
NaAlH4, Li3Na(NH2)4 and finally to NaH; where for Al, it changes
from LiAlH4 to NaAlH4, Na3AlH6 and LiAlN2H2. In the S-II, Na
changes from NaNH2 to NaAlH4, Li3Na(NH2)4; while Al changes
from LiAlH4 to NaAlH4, Li3AlH6 and Li2AlNH2. In the S-II sample a
competition between LiAlH4 and NaAlH4 to react with LiNH2
could exist because both complex hydrides present in the system
at the earlier stage of dehydrogenation. Because only NaAlH4 was
left, the reaction between LiAlH4 and LiNH2 could be more
favorable and the dehydrogenation process is thus resulted
from the interaction between LiAlH4 and LiNH2. Considering 2
equiv H2 were evolved and assuming NaH and NaAlH4 to be the
final Na-containing product in the S-I and S-II samples, the overall
reaction occurred in the milling process can be expressed by the
Scheme 1. Reaction pathways of S-I and S-II samples in the milling process.
reactions (6) and (7).
S-I LiAlH4+2NaNH2-2NaH+[LiAlN2H2]+2H2
S-II 2LiAlH4+NaNH2-NaAlH4+[Li2AlNH2]+2H2
(6)
(7)

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Y.S. Chua et al. / Journal of Solid State Chemistry 183 (2010) 2040–2044
equiv H2 were desorbed from both mixtures upon ball milling
showing the occurrence of interaction between the amide and
complex hydride. However, the hydrogen evolutions follow
different pathways in above two mixtures. Characterizations on
intermediates in the milling revealed that cation exchange takes
place at the initial stage of solid state reaction, which leads to
the formation of NaAlH4, Li3Na(NH2)4 (for S-I and S-II) and LiNH2
(for S-II). The interactions between NaAlH4 with Li3Na(NH2)4 and
NaNH2 are responsible for hydrogen evolution from S-I sample;
while for the S-II sample, the hydrogen mainly comes from the
interaction of LiNH2 with LiAlH4. Li–Al–N–H complexes with
chemical compositions of LiAlN2H2 and Li2AlNH2 were formed at
the end of ball milling in the S-I and S-II, which are ascribed to
LiAl(NH)2 imide and a metastable phase formed between LiH and
AlN, respectively.
Fig. 6. DSC (a) and TPD (b) measurements on S-I (solid line) and S-II (dash-dot
line) samples collected at the end of ball milling.
Acknowledgments
The authors wish to acknowledge financial supports from the
National Natural Science Foundation (CHINA, General Program
20971120), National 973 Project (CHINA, 2010CB631304) and
National University of Singapore (NUS, Singapore).
From the chemical composition point of view, the LiAlN2H2
formed in the S-I is likely to be a ternary imide of Li and Al,
i.e., LiAl(NH)2, which is supported by the observed broadband
absorbance centered at 3236 cmÀ1 in FTIR. In fact, there were
reports [25,26] that LiAl(NH)2 could be synthesized through the
thermal decomposition of LiAl(NH2)4. Herein the synthesis
process was repeated and the resulting LiAl(NH)2 was found
having the same FTIR absorbance with that of LiAlN2H2. However,
the synthesized LiAl(NH)2 is generally amorphous [25] and more
experimental evidences are demanded for its presence in the
milling residue of S-I. Li2AlNH2 complex formed in S-II sample,
on the other hand, is likely a mixture of 2LiH+AlN. Similar results
were reported by Dolotko et al. [17] in the investigation of
the LiAlH4/LiNH2 (1/1) system, whereby the dehydrogenation
of [LiAlH4–LiNH2] during the ball milling was proceeded by
two-step reactions:
References
[1] B. Bogdanovic, M. Schwickardi, J. Alloys Compd. 253 (1997) 1–9.
[2] G. Sandrock, K. Gross, G. Thomas, J. Alloys Compd. 339 (2002) 299–308.
[3] N.L. Rosi, J. Eckert, M. Eddaoudi, D.T. Vodak, J. Kim, M. O’Keeffe, O.M. Yaghi,
Science 300 (2003) 1127–1129.
[4] S.S. Kaye, J.R. Long, J. Am. Chem. Soc. 127 (2005) 6506–6507.
[5] M.E. Bluhm, M.G. Bradley, R. Butterick, U. Kusari, L.G. Sneddon, J. Am. Chem.
Soc. 128 (2006) 7748–7749.
[6] A.C. Stowe, W.J. Shaw, J.C. Linehan, B. Schmid, T. Autrey, Phys. Chem. Chem.
Phys. 9 (2007) 1831–1836.
[7] P. Chen, Z.T. Xiong, J.Z. Luo, J.Y. Lin, K.L. Tan, Nature 420 (2002) 302–304.
[8] H.Y. Leng, T. Ichikawa, S. Hino, N. Hanada, S. Isobe, H. Fujii, J. Phys. Chem. B
108 (2004) 8763–8765.
2LiAlH4+LiNH2-Li3AlH6+AlN+2H2
Li3AlH6+LiNH2-4LiH+AlN+2H2
(8)
(9)
[9] Z.T. Xiong, J.J. Hu, G.T. Wu, Y.F. Liu, P. Chen, Catal. Today 120 (2007) 287–291.
[10] T. Ichikawa, N. Hanada, S. Isobe, H.Y. Leng, H. Fujii, J. Phys. Chem. B 108
(2004) 7887–7892.
[11] W.F. Luo, J. Alloys Compd. 381 (2004) 284–287.
In our study, slight shifts of Li and Al from the LiH (0.54 ppm) and
AlN environments (see NMR results in Fig. 5) were observed
which could be resulted from the formation of metastable phase
between LiH and AlN after undergoing high energetic ball milling.
The thermal decompositions of the solid residues of S-I and S-II
were investigated by TPD and DSC. As shown in Fig. 6, the post-
milled S-I sample mainly presented two hydrogen signals, the
sharp endothermic peak centered at 320 1C characterizes the
decomposition of NaH and therefore that broad peak is the result
of dehydrogenation of LiAlN2H2. For the post-milled S-II sample,
thermal decomposition of NaAlH4 was observed. The overall
observations support the reactions (6) and (7).
[12] P. Chen, Z.T. Xiong, J.Z. Luo, J.Y. Lin, K.L. Tan, J. Phys. Chem. B 107 (2003)
10967–10970.
[13] Z. Xiong, G. Wu, J. Hu, P. Chen, J. Power Sources 159 (2006) 167–170.
[14] Z.T. Xiong, G.T. Wu, J.J. Hu, Y.F. Liu, P. Chen, W.F. Luo, J. Wang, Adv. Funct.
Mater. 17 (2007) 1137–1142.
[15] Y. Nakamori, A. Ninomiya, G. Kitahara, M. Aoki, T. Noritake, K. Miwa,
Y. Kojima, S. Orimo, J. Power Sources 155 (2006) 447–455.
[16] J. Lu, Z.Z. Fang, J. Phys. Chem. B 109 (2005) 20830–20834.
[17] O. Dolotko, H.Q. Zhang, O. Ugurlu, J.W. Wiench, M. Pruski, L.S. Humbley,
V. Pecharsky, Acta Mater. 55 (2007) 3121–3130.
[18] T.N. Dymova, D.P. Aleksandrov, V.N. Konoplev, T.A. Silina, A.S. Sizareva,
Koordinatsionnaya Khim. 20 (1994) 279–285.
[19] V.P. Balema, K.W. Dennis, V.K. Pecharsky, Chem. Commun. (2000) 1665–1666.
[20] R.L. Lowton, M.O. Jones, W.I.F. David, S.R. Johnson, M. Sommariva,
P.P. Edwards, J. Mater. Chem. 18 (2008) 2355–2360.
[21] Z.T. Xiong, G.T. Wu, J.J. Hu, P. Chen, Adv. Mater. 16 (2004) 1522–1525.
[22] J.W. Wiench, V.P. Balema, V.K. Pecharsky, M. Pruski, J. Solid State Chem. 177
(2004) 648–653.
4. Conclusion
[23] B. Bogdanovic, M. Felderhoff, M. Germann, M. Hartel, A. Pommerin, F. Schuth,
C. Weidenthaler, B. Zibrowius, J. Alloys Compd. 350 (2003) 246–255.
[24] J.J. Fitzgerald, S.D. Kohl, G. Piedra, Chem. Mater. 6 (1994) 1915.
[25] R. Janot, J.B. Eymery, J.M. Tarascon, J. Phys. Chem. C 111 (2007) 2335–2340.
[26] J. Rouxel, R. Brec, C. R. Acad. Sci. Ser. C 262 (1966) 1070.
In this study, LiAlH4–NaNH2 mixtures with LiAlH4/NaNH2
molar ratio at 1/2 and 2/1 were investigated. It was found that 2