Abstract:
Density functional theory is used to study sulvanite compound(VCu3S4) both the cubic
and tetragonal phase. The lattice parameter in case of tetragonal phase is as following,
𝑎 = 𝑏 = 5.3096 while the ratio of 𝑐
โ𝑎 = 1.05 which shows that 𝑐 = 5.5750 under
relax calculation. While in case of cubic 𝑎 = 𝑏 = 𝑐 == 5.4642. both phases are first
optimized and found the minimum energy at these values of the lattice vectors. Both
the phases are observed to have indirect band gap and the band gap is found to be
1.88eV for tetragonal phase and 1.01eV eV for cubic phase. Partial density of state and
total density of state are also studied which provide further confirmation of the band
gap and other electronic properties of the material. Boltztrap code is used to investigate
the thermoelectric properties of both the phases of the material (cubic and tetragonal
phase). We determined the ZT values, for cubic phase the highest ZT value achieved at
CBM is 0.75 at 500K temperature and at VBM the highest value is 0.73 at 800K. while
in case of tetragonal phase the highest ZT achieved at CBM is 0.85 at 1200K
temperature and at VBM the highest ZT value is 0.8 at 1100K temperature. The values
of ZT shows that the material is good for thermoelectric purposes. Also, the novelty of
this manuscript is the study of the tetragonal phase of the material, which looks good
regards to the ZT value.
