Synthesis and structure of the bilayer hydrate Na0.3NiO 2·1.3D2O

Article abstract of DOI:10.1021/ic060235x

The metal oxide bilayer deuterate (hydrate) Na_0.3NiO ₂·1.3D₂O (Na_0.3NiO₂·1. 3H₂O) were prepared from Na_xNiO₂ by extracting Na⁺ cations and simultaneously intercalating fully and nondeuterated water. High-resolution neutron powder diffraction, thermogravimetric analysis, and inductively coupled plasma atomic emission spectroscopy were used to show that a Na_0.3(D₂O)_1.3 network separates layers of edge-sharing NiO₆ octahedra.

Full text of DOI:10.1021/ic060235x

Inorg. Chem. 2006, 45, 3490−3492
Synthesis and Structure of the Bilayer Hydrate Na NiO2‚1.3D O
0.3
2
Sangmoon Park,†,‡ Yongjae Lee,‡ Margaret Elcombe,§ and Thomas Vogt*,†
USC NanoCenter and Department of Chemistry and Biochemistry, UniVersity of South Carolina,
Columbia, South Carolina 29208, Department of Earth System Sciences, Yonsei UniVersity, Seoul
1
20749, South Korea, and Bragg Institute, Australian Nuclear Science & Technology
Organization, Sydney, Australia
Received February 11, 2006
6
The metal oxide bilayer deuterate (hydrate) Na0.3NiO
2
‚
1.3D
2
O
mineral birnessite Na0.32MnO
three-layer MLH family Na0.3CoO
prepared. Several BLHs have also been made: the super-
2
‚0.67H
2
O. A member of the
+
7
(
Na0.3NiO
2
‚
1.3H
2
O) were prepared from Na
x
NiO
2
by extracting Na
2
2
‚0.6H O has also been
cations and simultaneously intercalating fully and nondeuterated
water. High-resolution neutron powder diffraction, thermogravimetric
analysis, and inductively coupled plasma atomic emission spec-
7
conducting two- and three-layer BLH Na0.3CoO
the mineral buserite Na0.3MnO ‚nH O, and Mg-, Ca-, Ni-,
and Co-exchanged birnessites. We will show in this work
that Na0.3NiO ‚1.3H O is a two-layer BLH and isostructural
to Na0.3CoO ‚1.3H O.
Powder samples of Na
heating a 20 mol % excess of Na
amorphous NiO at 600 °C for 8 h in an O
NiO was made by heating Ni(OH) (Alfa) or Ni(NO
Alfa 99.9985%) at 300 °C for 1 day. Two types of samples
were synthesized: the hydrated analogue Na NiO ‚yH O used
for characterization experiments and the deuterated (D O,
Alfa, 99.8%) analogue Na NiO ‚yD O used only for neutron
powder diffraction. Both samples were oxidized and hydrated
2 2
‚1.3H O,
2
2
8
2
troscopy were used to show that a Na0.3(D O)1.3 network separates
2
2
layers of edge-sharing NiO octahedra.
6
2
2
x
NiO
2
(x e 1) were prepared by
(Alfa, 97%) with
(g) atmosphere.
2
‚6H O
2 2
O
Structures with the general composition A+
2 y 2
(H O) [MX
]x-
x
2
provide the opportunity to tune the charge within the MX
2
2
)
3 2
layers by appropriate oxidation as well as to manipulate the
distance between them by varying the degree of hydration.
The discovery of superconductivity near 5 K in the systems
(
x
2
2
+
x-
2+
x-
2
A
x
2
(H O)
y
[MX
2
]
and A x/2(H
2
O)
y
2
[MX ]
for M ) Nb
+
2+
x
2
2
and Ta, X ) S, A ) Li, Na, K, Rb, and Cs, and A ) Ca,
Sr, and Ba by Sernetz et al. provided early evidence of the
1
(
or deuterated) by mixing an aqueous solution of Na
2 2 8
S O
exciting physics present in the mono- and bilayer hydrates
(
pH ∼ 10.5) in a molar ratio of 1.6:1 with Na NiO
x
2
and
(
MLH and BLH), where a single cation-water layer or a
sequence of cation-water-cation layers separates the doped
two-dimensional MS layers by distances of approximately
and 10 Å, respectively. The recent discovery of supercon-
ductivity in the BLH Na0.3CoO ‚1.3H O near 5 K and the
stirring it for 1 day in a Pyrex bottle. The Na (x ∼ 0.3) and
water contents (y ∼ 1.3) in Na
x
NiO ‚yH O were determined
2
2
2
by inductively coupled plasma atomic emission spectrometry
and thermogravimetric analysis (TGA) upon heating at 0.25
C/min in flowing Ar, respectively. Ni K-edge X-ray
absorption spectroscopy experiments were performed on a
Beamline X11A at the National Synchrotron Light Source
and reveal an absorption edge shift toward higher energies
‚1.3H O compared to Na0.7NiO . This indicates
2 2
that because of the oxidation process Ni occurs in two
possible electronic configurations: a combination of 3d (S
) and 3d (S ) 0) or 3d L states, with L representing
a hole in the O p states. Neutron powder diffraction data of
‚1.3D O with thermal neutrons of wavelength 1.885
Å were collected on the high-resolution neutron powder
diffractometer at the Australian Nuclear Science and Tech-
7
2
2
°
subsequent exploration of this correlated electron system
provided the impetus to systematically explore the chemistry
and physics of other members of the A (MO )(H O) family.
x 2 2 n
Up to now, several compounds of the two-layer MLH
in Na0.3NiO
2
systems have been prepared and, to varying degrees,
2
characterized. These include Na0.36CoO
2
‚0.7H
2
O, K0.3CoO
2
‚
7
3
4
5
2 2 2
0.4H O, Na0.3RhO ‚0.6H O, Na0.22RuO
2
‚0.45H
2
O, and the
1
6
7
)
/
2
*
To whom correspondence should be addressed. E-mail:
tvogt@gwm.sc.edu.
Na0.3NiO
2
2
†
University of South Carolina.
Yonsei University.
Australian Nuclear Science & Technology Organization.
‡
§
(
(
(
(
1) Sernetz, F.; Lerf, A.; Sch o¨ llhorn, R. Mater. Res. Bull. 1974, 9, 1597-
1602.
(5) Shikano, M.; Delmas, C.; Darriet, J. Inorg. Chem. 2004, 43, 1214-
1216.
2) Takada, K.; Sakurai, H.; Takayama-Muromachi, E.; Izumi, F.;
Dilanian, R. A.; Sasaki, T. J. Solid State Chem. 2004, 177, 372-376.
3) Park, S.; Lee, Y.; Si, W.; Vogt, T. Solid State Commun. 2005, 134,
(6) Jones, L. H. P.; Milne, A. A. Mineral. Mag. 1956, 31, 283-288.
(7) Foo, M. L.; Klimczuk, T.; Li, L.; Ong, N. P.; Cava, R. J. Solid State
Commun. 2005, 133, 407-410.
(8) Le Goff, P.; Baffier, N.; Bach, S.; Pereira-Ramos, J. P. Mater. Res.
Bull. 1996, 31, 63-75.
607-611.
4) Park, S.; Kang, K.; Si, W.; Yoon, W.-S.; Lee, Y.; Moodenbaugh, A.
R.; Lewis, L. H.; Vogt, T. Solid State Commun. 2005, 135, 51-56.
3490 Inorganic Chemistry, Vol. 45, No. 9, 2006
10.1021/ic060235x CCC: $33.50
© 2006 American Chemical Society
Published on Web 04/05/2006

COMMUNICATION
Table 1. Atomic Coordinates of Na0.3NiO2‚1.3D2Oa
atom
x
y
z
occupancy
Uiso (Å2)
Ni
O
Na
OW
D
0
0
0
0
0
0
1
1
0.049(3)
0.049(3)
0.049(3)
0.049(3)
0.049(3)
0.719(1)
0.11(4)
0.323(5)
0.069(3)
0.0926(6)
0.52(2)
0.630(3)
0.326(2)
0.15
0.67(1)
0.67(1)
0.239(1)
a
Space group C2/m; a ) 4.890(2) Å, b ) 2.9361(9) Å, c ) 10.542(2)
3
Å, â ) 107.81(2)°, V ) 144.09(6) Å . wRp ) 11.8%, Rp ) 9.01%. OW
denotes the water O atom. Restraints were used to tie isotropic displacement
parameters for all atoms. Bond distance/angle constraints were used for
D2O molecules.
Table 2. Selected Bond Distances and Angles of Na0.3NiO2‚1.3D2O
bond
distance or angle
bond
distance or angle
Figure 1. Rietveld refinement fit of the structural model of Na0.3NiO2‚
.3D2O to neutron powder diffraction data measured at 23 K. Points shown
Ni-O
1.916(5) × 2
1.900(4) × 4
2.20(20)
2.53(18) × 2
2.25(18) × 2
2.996(32)
OW-OW
2.852(1)
2.936(1)
2.99(4)
0.967(5)
104.7(7)
1
represent the observed intensities. The continuous lines through the sets of
points are the calculated profiles from the refined model summarized in
Tables 1 and 2. The sets of tick marks below the data indicate the positions
of the allowed reflections (lower, Na0.3NiO2‚1.3D2O; middle, ice XI; upper,
Na2SO4). The lower curves represent the differences between observed and
calculated profiles (Iobs - Icalc) plotted on the same scale as the observed
data.
Na-OW
OW-Da
D-OW-Da
OW-O
a
Bond distance/angle constraints were used for D2O molecules.
nology Organization’s Research Reactor in Lucas Heights,
Australia. All refinements were carried out using the Rietveld
method and the GSAS package.
The X-ray powder diffraction pattern showed that the
monoclinic symmetry (C2/m) is preserved during the trans-
formation from Na
response to the oxidation and hydration of Na
in a manner similar to what is observed in Na0.7CoO
x
NiO
2
to Na0.3NiO
2
‚1.3H
2
O. The structural
NiO occurs
: a
x
2
2
large expansion of the c axis occurs as a result of water
intercalation accompanied by a slight contraction of the a
and b axes due to shortening of the Ni-O bond distances in
Figure 2. Polyhedral representation of the structure of Na0.3NiO2‚1.3D2O
viewed along the a and b axes. The dotted lines in the figures define unit
cells.
6
the NiO octahedra, resulting from partial oxidation of
formally Ni3 to Ni . The neutron powder diffraction pattern
measured at 23 K reveals a mixture of three crystalline
phases, with the majority phase identified as sodium nickel
oxydeuterate. Also present were two impurity phases: ice
+
4+
in Figure 1. The refined structural model is summarized in
Table 1, and selected interatomic distances are listed in Table
2
. TGA measurements carried out showed that the completely
dehydrated phase was obtained after a weight loss of about
9% relative to Na0.3NiO ‚1.3H O, with a rapid weight drop
XI (∼5%) and Na
2
SO
4
(∼5%). The water impurity phase is
due to dehydration occurring during the filling of the V
container done under standard humidity conditions in a
1
2
2
observed below 150 °C. An intermediate phase at a weight
loss of about 11% corresponding to 0.7 mol % water per
formula unit was observed. This phase is a MLH phase
glovebag, and the Na
the deintercalation that was not completely removed from
2
the product. The structural refinement of Na0.3NiO ‚1.3D O
2 4
SO impurity is a reaction product of
2
similar to the one observed in sodium cobalt oxyhydrate
proceeded using the space group C2/m in an expanded layer
model with Ni and O atoms located at the positions (0, 0, 0)
and (0.7, 0, 0.1), respectively. Difference Fourier maps were
generated that allowed the location of the intercalated water
molecules. O atoms at (0.32, 0, 0.63) and D atoms at (0.07,
2
Na0.36CoO
2
‚0.7H
2
O and will be discussed in a forthcoming
9
paper. The structure of Na0.3NiO
2
‚1.3D
octahedra separated by layers of D
molecules coordinating to Na cations (Figure 2). It is con-
firmed that the NiO octahedra are in a triangular arrange-
ment typical of BLHs. The refined water content, 1.35(2)
O per formula unit, is very close to the independently
2
O at 23 K consists
of layers of NiO
2
2
O
2
0.24, 0.32) were constrained during the refinement to
conform to the ideal molecular geometry of water. Successive
difference Fourier sections were calculated to locate the
D
2
determined value obtained by TGA. This agreement gives
us confidence that the presence of water as an impurity occur-
red only in the neutron measurement and certainly to a lesser
degree because of the smaller sample size in the TGA
measurement. The D O layers sandwich the central Na layer,
2
consistent with the BLH model, as observed in the sodium
2
residual scattering density within the D O layers at (0.11, 0,
0.52). Subsequently, this site was modeled by placing a Na
atom with a fixed site occupancy according to the chemical
analysis results. In the final refinement, the occupancies for
the O and D atoms of water were constrained to be 1:2, and
additional constraints were used for the isotropic displace-
ment parameters of all atoms. The final profile fit is depicted
(9) Park, S.; Vogt, T. Unpublished.
Inorganic Chemistry, Vol. 45, No. 9, 2006 3491

COMMUNICATION
cobalt hydrate with a similar water content. The interlayer
2
the shortest O-O distance [2.85(1) Å] in each D O layer is
spacing of Na0.3NiO
2
‚1.3D
2
O is expanded to ca. 10.14 Å
along the diagonal of the xy plane, whereas along the y axis,
the O-O separation is 2.94(1) Å (Table 2). Another similar
3+
compared to ca. 9.81 Å observed in Na0.3CoO
2
‚1.3H
) is a Jahn-Teller active ion, and the electronic e
levels will split. The elongated NiO octahedra at 23 K with
2
O. Ni
6
1
(t
2g
e
g
g
O-O separation [3.00(3) Å] is found between the D
NiO layers, indicating weak H bonding between them. On
average, each D O molecule is H-bonded to four neighboring
O molecules within its layer and an O atom in the adjacent
NiO layer. Furthermore, the D O molecule is coordinated
2
O and
6
2
two axial Ni-O distances of 1.916(5) Å and four equatorial
ones at 1.900(4) Å are both significantly shorter than those
2
D
2
observed in RNiO
the Ni-O distances are all larger than 1.93 Å. In NaNiO
the elongated NiO octahedra are comprised of two Ni-O
distances at 2.17 Å and four at 1.95 Å. Short distances
similar to those found in Na0.3NiO ‚1.3D O have only been
observed in BaNiO (Ni-O at 1.89 Å), where Ni has a
formal valence state of 4+.12 It is interesting to note that
3
materials (R ) La, Pr, Nd, and Sm) where
2
2
10
2
,
to a Na cation in the central layer.
6
The magnetic properties of the new metal oxide BLH
Na NiO ‚1.3H O were investigated. Dc and ac magnetic
11
0
.3
2
2
2
2
susceptibility measurements revealed this compound to be
a spin glass at low temperatures. These results will be
discussed in a forthcoming publication in more detail.
3
(
(
(
10) Garcia-Munoz, J. L.; Rodriguez-Carvajal, J.; Lacoore, P.; Torrance,
J. B. Phys. ReV. B 1992, 46, 4414-4425.
11) Dyer, L. D.; Borie, B. S., Jr.; Smith, G. P. J. Am. Chem. Soc. 1954,
Acknowledgment. T.V. thanks the Bragg Institute at the
Australian Nuclear Science & Technology Organization for
its repeated hospitality during extended periods of visitation.
7
6, 1499-1503.
12) Krischner, H.; Torkar, K.; Kolbsen, B. O. J. Solid State Chem. 1971,
, 349-357.
3
IC060235X
3492 Inorganic Chemistry, Vol. 45, No. 9, 2006