3.3. Electronic properties
To study the conductivity and bonding characteristics, we further
studied the electronic properties of
Ti3AlB2,
Ti2ZrAlB2-1 and
Ti2ZrAlB2-2. As is shown in Figure 3,
the finite positive values of density of states near Fermi level shows
that they all have good electrical conductivity. From the case of
partial density of states, it can be seen the conductivity are mainly
contributed by Ti-d and B-p electron orbitals for
Ti3AlB2, and Ti-d, Zr-d and B-p electron
orbitals for two Ti2ZrAlB2. For
Ti3AlB2 and
Ti2ZrAlB2-2, the similar shape of
partial density of states for Ti-d and B-p electron near Fermi level
means show there is strong orbital hybridization between these two types
of electrons. And the shape of Ti-d and Zr-d orbitals are similar for
Ti2ZrAlB2-2, it indicates that metal
bonds can also be formed between Zr and Ti atoms. While for
Ti2ZrAlB2-1, Zr atoms also participate
in bonding, which reduces the similarity of PDOS between Ti and B atoms
compared with Ti3AlB2 and
Ti2ZrAlB2-2. It indicates the ionic
bonds in Ti3AlB2 and
Ti2ZrAlB2-2 are stronger than that in
Ti2ZrAlB2-1, this is also consistent
with the result of Poisson ratio discussed earlier.