MgH2 is a promising compound for hydrogen storage. Its relatively high stability has been the main obstacle for practical applications. Here, the authors report a first principles prediction of a metastable phase of MgH2. The predicted phase is characterized by tetragonal symmetry (I41amd, group 141) with the lattice parameters a=0.3813nm and c=0.9416nm and meets all the mechanical stability criteria. Its heat of formation is 58.03kJmolH2, which is much less negative than that of the α-MgH2 phase (76kJmolH2). Hence, the tetragonal structure is more desirable than the α-MgH2 for practical hydrogen storage applications.

1.
D. L.
Douglass
,
Proceedings of the Ninth International Symposium on Hydrides for Energy Storage
, edited by
A. F.
Anderson
and
A. J.
Maeland
(
Pergamon
,
Oxford
,
1978
), p.
151
.
2.
X.
Shang
,
M.
Bououdina
, and
Z. X.
Guo
,
J. Alloys Compd.
349
,
217
(
2003
).
3.
P.
Selvam
,
B.
Viswanathan
,
C. S.
Swamy
, and
V.
Srinivasan
,
Int. J. Hydrogen Energy
11
,
169
(
1986
).
4.
P.
Vajeeston
,
P.
Ravindran
,
A.
Kjekshus
, and
H.
Fjellvåg
,
Phys. Rev. Lett.
89
,
175506
(
2002
).
5.
M.
Bortz
,
B.
Bertheville
,
G.
Böttger
, and
K.
Yvon
,
J. Alloys Compd.
287
,
L4
(
1999
).
6.
L. A.
Errico
,
G.
Fabricius
, and
M.
Rentería
,
Phys. Rev. B
67
,
144104
(
2003
).
7.
B. G.
Hyde
and
S.
Andersson
,
Inorganic Crystal Structures
(
Wiley
,
New York
,
1989
), p.
69
.
8.
T. E.
Weirich
,
M.
Winterer
,
S.
Seifried
, and
J.
Mayer
,
Acta Crystallogr., Sect. A: Found. Crystallogr.
58
,
308
(
2002
).
9.
P.
Blaha
,
K.
Schwarz
, and
J.
Luitz
, WIEN2K, Vienna University of Technology,
2000
.
10.
D.
Singh
,
Plane Waves, Pseudopotentials, and the LAPW Methods
(
Kluwer Academic
,
New York
,
1994
).
11.
J. P.
Perdew
,
S.
Burke
, and
M.
Ernzerhof
,
Phys. Rev. Lett.
77
,
3865
(
1996
).
12.
M.
Weinert
,
E.
Wimmer
, and
A. J.
Freeman
,
Phys. Rev. B
26
,
4571
(
1982
).
13.
Y.
Song
,
Z. X.
Guo
, and
R.
Yang
,
Phys. Rev. B
69
,
094205
(
2004
).
14.
P.
Ravindran
and
R.
Asokamani
,
Phys. Rev. B
50
,
668
(
1994
).
15.
J. H.
Xu
and
A. J.
Freeman
,
Phys. Rev. B
41
,
12553
(
1990
).
16.
P.
Vajeeston
,
P.
Ravindran
,
A.
Kjekshus
, and
H.
Fjellvåg
,
Phys. Rev. B
69
,
020104
(
2004
).
17.
S. K.
Patil
,
S. V.
Khare
,
B. R.
Tuttle
,
J. K.
Bording
, and
S.
Kodambaka
,
Phys. Rev. B
73
,
104118
(
2006
).
18.
D. C.
Wallace
,
Thermodynamics of Crystals
(
Wiley
,
New York
,
1972
), Chap. 1.
19.
K.
Zeng
,
T.
Klassen
,
W.
Oelerich
, and
R.
Bormann
,
J. Appl. Phys.
283
,
213
(
1999
).
You do not currently have access to this content.