TY - JOUR
T1 - The ionic conductivity in lithium-boron oxide materials and its relation to structural, electronic and defect properties
T2 - Insights from theory
AU - Islam, Mazharul M.
AU - Bredow, Thomas
AU - Heitjans, Paul
PY - 2012/4/27
Y1 - 2012/4/27
N2 -
We review recent theoretical studies on ion diffusion in (Li
2
O)
x
(B
2
O
3
)
1x
compounds and at the interfaces of Li
2
O :B
2
O
3
nanocomposite. The investigations were performed theoretically using DFT and HF/DFT hybrid methods with VASP and CRYSTAL codes. For the pure compound B
2
O
3
, it was theoretically confirmed that the low-pressure phase B
2
O
3
I has space group P3
1
21. For the first time, the structure, stability and electronic properties of various low-index surfaces of trigonal B
2
O
3
I were investigated at the same theoretical level. The (101) surface is the most stable among the considered surfaces. Ionic conductivity was investigated systematically in Li
2
O, LiBO
2
, and Li
2
B
4
O
7
solids and in Li
2
O:B
2
O
3
nanocomposites by calculating the activation energy (E
A
) for cation diffusion. The Li
+
ion migrates in an almost straight line in Li
2
O bulk whereas it moves in a zig-zag pathway along a direction parallel to the surface plane in Li
2
O surfaces. For LiBO
2
, the migration along the c direction (E
A
=0.55eV) is slightly less preferable than that in the xy plane (E
A
=0.430.54eV). In Li
2
B
4
O
7
, the Li
+
ion migrates through the large triangular faces of the two nearest oxygen five-vertex polyhedra facing each other where E
A
is in the range of 0.270.37eV. A two-dimensional model system of the Li
2
O :B
2
O
3
interface region was created by the combination of supercells of the Li
2
O (111) surface and the B
2
O
3
(001) surface. It was found that the interface region of the Li
2
O :B
2
O
3
nanocomposite is more defective than Li
2
O bulk, which facilitates the conductivity in this region. In addition, the activation energy (E
A
) for local hopping processes is smaller in the Li
2
O :B
2
O
3
nanocomposite compared to the Li
2
O bulk. This confirms that the Li
2
O :B
2
O
3
nanocomposite shows enhanced conductivity along the phase boundary compared to that in the nanocrystalline Li
2
O.
AB -
We review recent theoretical studies on ion diffusion in (Li
2
O)
x
(B
2
O
3
)
1x
compounds and at the interfaces of Li
2
O :B
2
O
3
nanocomposite. The investigations were performed theoretically using DFT and HF/DFT hybrid methods with VASP and CRYSTAL codes. For the pure compound B
2
O
3
, it was theoretically confirmed that the low-pressure phase B
2
O
3
I has space group P3
1
21. For the first time, the structure, stability and electronic properties of various low-index surfaces of trigonal B
2
O
3
I were investigated at the same theoretical level. The (101) surface is the most stable among the considered surfaces. Ionic conductivity was investigated systematically in Li
2
O, LiBO
2
, and Li
2
B
4
O
7
solids and in Li
2
O:B
2
O
3
nanocomposites by calculating the activation energy (E
A
) for cation diffusion. The Li
+
ion migrates in an almost straight line in Li
2
O bulk whereas it moves in a zig-zag pathway along a direction parallel to the surface plane in Li
2
O surfaces. For LiBO
2
, the migration along the c direction (E
A
=0.55eV) is slightly less preferable than that in the xy plane (E
A
=0.430.54eV). In Li
2
B
4
O
7
, the Li
+
ion migrates through the large triangular faces of the two nearest oxygen five-vertex polyhedra facing each other where E
A
is in the range of 0.270.37eV. A two-dimensional model system of the Li
2
O :B
2
O
3
interface region was created by the combination of supercells of the Li
2
O (111) surface and the B
2
O
3
(001) surface. It was found that the interface region of the Li
2
O :B
2
O
3
nanocomposite is more defective than Li
2
O bulk, which facilitates the conductivity in this region. In addition, the activation energy (E
A
) for local hopping processes is smaller in the Li
2
O :B
2
O
3
nanocomposite compared to the Li
2
O bulk. This confirms that the Li
2
O :B
2
O
3
nanocomposite shows enhanced conductivity along the phase boundary compared to that in the nanocrystalline Li
2
O.
UR - http://www.scopus.com/inward/record.url?scp=84860321273&partnerID=8YFLogxK
U2 - 10.1088/0953-8984/24/20/203201
DO - 10.1088/0953-8984/24/20/203201
M3 - Review article
AN - SCOPUS:84860321273
SN - 0953-8984
VL - 24
JO - Journal of Physics Condensed Matter
JF - Journal of Physics Condensed Matter
IS - 20
M1 - 203201
ER -