The thermoelectric properties of the two-dimensional Nowotny-Juza material NaBeX (X = P, As, and Sb)

The two-dimensional β-type Nowotny-Juza phase-filled tetrahedral compound has excellent electrical conductivity, low thermal conductivity and outstanding thermoelectric properties. This study investigated the stability and electronic properties of NaBeX (X = P, As, and Sb) through first-principles calculations. The results demonstrate that these materials are structurally stable and are direct bandgap semiconductors with bandgaps of 0.6542 eV, 0.6549 eV, and 0.6686 eV, respectively. The electrical and thermal transport properties of NaBeX are investigated by combining the deformation potential theory and Boltzmann transport theory. Subsequently, the thermoelectric properties of NaBeX are evaluated at temperatures ranging from 400 to 800 K. The n-type NaBeX materials exhibit large ZT values of 2.48, 2.62, and 1.72. The results of the present study indicate that n-type NaBeX has the potential to be used as a thermoelectric candidate material at temperatures ranging from 400 to 800 K.