Cubic to tetragonal structural phase transformation in NaNbO3 with peculiar Mg and Ca doping and its repercussions on optoelectronic properties

By using computation, scrutinize the impact of doping on phase stability, phase transformation, electronic band structure, and optical properties of NaNbO3 are reported. At peculiar doping concentrations (4.22% Mg, 7.04% Mg, 4.22% Ca and 7.04% Ca), cubic to pseudo-cubic tetragonal phase transformation occurs. The total DOS, partial DOS and elemental PDOS explain the effect of phase transformation on band structure. In all cases of doping, the value of band gap increases and the nature of band gap for 4.22% doping concentrations remains same as that of pure and becomes direct band gap for 1.40% and 7.04% doping concentrations. From optical properties, we observed a red shift in the absorption spectra and the refractive index increases from 2.60 to 3.80 and 3.90 with Ca- and Mg-doping, respectively. •A detailed study of structural phase transformation and its impact on optoelectronic properties by Mg and Ca doping in NaNbO3.•Cubic to tetragonal phase transformation occurs at peculiar doping concentration.•The doping of Ca and Mg at Na site in NaNbO3 finely tune the band gap of the compound.•The refractive index increases from 2.60 to 3.80 and 3.90 with Ca- and Mg-doping.•The absorption edge shifted to lower energy with doping.