Impact of anion replacement on the optoelectronic and thermoelectric properties of CaMg2X2, X= (N, P, As, Sb, Bi) compounds

The structural, electronic, optical and thermoelectric properties of ternary CaMg2X2 (X = N, P, As, Sb and Bi) compounds are investigated using all electrons full potential linearized augment plane wave method. By using generalized gradient approximation (GGA), unit cell volumes of the compounds are...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 2018-07, Vol.541, p.24-31
Main Authors: Khan, Abdul Ahad, Yaseen, M., Laref, A., Murtaza, G.
Format: Article
Language:English
Subjects:
DOS
Energy gap
Intraband transitions
Zintl compounds
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Summary:The structural, electronic, optical and thermoelectric properties of ternary CaMg2X2 (X = N, P, As, Sb and Bi) compounds are investigated using all electrons full potential linearized augment plane wave method. By using generalized gradient approximation (GGA), unit cell volumes of the compounds are optimized. For calculations of optical and electronic properties the modified Becke Johnson exchange potential is used along with the GGA. The direct energy band gap decreases by replacing the pnictogen elements, while indirect bandgap also decreases except for CaMg2As2. The optical properties show a prominent variation over the change of anion from N to Bi. There is inverse variation between refractive index and the band gap. The refractive indices of these compounds are high in the visible region and sharply decreased in the ultraviolet region. The thermoelectric properties are also studied using Boltzmann statistics through BoltzTrap code. A positive non-zero value of Seebeck coefficient shows a P-type semiconducting behavior of these compounds. High figure of merits (ZT) and optical conductivity peaks for all compounds reveal that they are good candidates for the thermo-electric and optoelectronics devices. •CaMg2X2 (X = N, P, As, Sb and Bi) compounds are studied by FP-LAPW + lo method.•Major part is played by X-p state and Ca-d states in the valence/conduction bands.•Mixed covalent and ionic-like character bonding observed.•There is an inverse variation between refractive index and energy band gap.•A positive value of Seebeck coefficient shows these as P-type semiconductors.
ISSN:0921-4526
1873-2135
DOI:10.1016/j.physb.2018.04.034