First-principles study of ZnAl ₂ O ₄ for energy applications

In this study, the wide-bandgap oxide spinel ZnAl 2 O 4 , which has a cubic Fd-3m structure, is investigated for its structural, electrical and thermoelectric properties. The FP-LAPW technique and GGA[Formula: see text]mBJ potential are used in first-principles calculations, which show a direct bandgap of 4.2[Formula: see text]eV at the [Formula: see text]-point. Strong temperature and chemical potential relying is shown in the Seebeck coefficient (S), which reaches values over [Formula: see text] 23,000 [Formula: see text]V/K close to [Formula: see text] [Formula: see text]eV at 500[Formula: see text]K. S is decreased by bipolar conduction, which is caused through higher temperatures. According to an analysis of electrical ([Formula: see text]/[Formula: see text]) and thermal ([Formula: see text]/[Formula: see text] conductivities, p-type conduction is favorable. At 1100[Formula: see text]K, ZT values approach 1.2 due to increased carrier excitation and decreased lattice thermal conductivity. Balanced performance for both carrier types is indicated by broad, symmetric ZT peaks around [Formula: see text]. These results indicate that ZnAl 2 O 4 is a potential high-temperature thermoelectric material. To maximize its effectiveness in energy recovery applications, doping and thermal tuning are crucial. It is an energy-storing material below 500 K.