L
Bonding type
R
tetra
a
R
octa
a
R
tetra
b
R
octa
b
Zn –O
(I)1.947
(N)2.067
(I)2.060
1.975
2.082
Sn –O
(N)1.953
(I)2.063
1.970
2.067
a
our work
b
ref.
(D. Segev
et al
., 2005, R. J. Hill
et al
., 1979)
Composition of the calculated energy bands can be resolved with the help of partial density of states (PDOS) and total
density of states (DOS) diagrams, as shown in Fig. 3(a) and Fig. 3(b), for normal and inverse spinel structure of
SnZn
2
O
4
, respectively. We found that the top of valence band consists predominantly of cation
d
and O
p
states,
which hybridized strongly, whereas the bottom of conduction band arises mostly from the mixture of oxygen and
cation
s
states. These diagrams allow concluding that the conduction band edge in normal spinel structure of SnZn
2
O
4
is about 10.9 eV wide and is formed by the Sn-
sp
states that are hybridized with the Zn-
sp
and O-
p
states. The valence
band is wide – about 9.7 eV – and consists of two sub-bands, clearly seen in the band structure as well: the upper one
(between -9.6 and 0 eV) is a mixture of Sn-
sp
, Zn-
d
and O-
p
states. The lower one narrows (between -9.7 and -9.6 eV)
and due to the Sn-sp states with admixture from Zn-
d
and O-
p
states. Another band between -15.9 and -19.6 eV is
show to be of predominantly O-
s
states with minor contribution of Sn-
sp
and Zn-
s
,
p
,
d
states.
( a) ( b )
Fig. 2
Band structure of (a) normal and (b) inverse spinel of SnZn
2
O
4
.
