A computational insight into the Zintl SZr2N2 and BaAg2S2 phases for optoelectronic thermoelectric applications

Abstract

The physical characteristics of SZr2N2 and BaAg2S2 Zintl phases have been explored by utilizing the full-potential augmented plane wave (FP-LAPW) method with the combination of modified Becke-Johnson (mBJ) approximation. The negative formation energies and phonon modes with positive frequencies endorsed the stability of both compounds. The electronic band profile reveals a bandgap of 1.18 eV for SZr2N2 and 2.15 eV for BaAg2S2. The optical characteristics are also calculated. The absorption of light for the studied compounds falls in the ultra-violet region, which shows their possibility to be employed as UV-rays absorbers. A large optical conductivity and low energy loss is also seen for both materials on UV region. The efficiency of temperature-dependent thermoelectric properties increases with the temperature rise, as calculated with the BoltzTraP code. The high electrical with low thermal conductivities and maximum Seebeck coefficient is witnessed for both materials. The large ZT values of 0.75 and 0.80 are achieved for SZr2N2 and BaAg2S2, respectively. All calculated transport parameters indicate the opportunity of using the studied compounds for thermoelectric applications.