Prediction of high thermoelectric potential in AMN2 layered nitrides: electronic structure, phonons, and anharmonic effects

Rabih Al Rahal Al Orabi, Esther Orisakwe, Daehyun Wee, Bruno Fontaine, Regis Gautier, Jean-François Halet, and Marco Fornari, Prediction of high thermoelectric potential in AMN2 layered nitrides: electronic structure, phonons, and anharmonic effects. Journal of Materials Chemistry A, 2015, Advance Article. doi:10.1039/c5ta00546a

 

Band structures, electronic transport coefficients, harmonic and anharmonic vibrational properties of novel
layered nitrides have been studied to evaluate the potential for thermoelectric applications. Using first
principles theoretical methods we predict that AMN 2 compounds with A: Ca, Sr, and Ba, and M: Ti, Zr,
Hf may exhibit Seebeck coefficients in excess of 150 mV K^-1 and good electrical conductivities. The
phonon dispersions indicate the presence of low lying optic modes that can lead to low thermal
conductivity. The analysis of the mode resolved Gruneisen parameter points to large anharmonicity. In
addition, we show that the A-site substitution controls the degeneracies at the top of the valence band
and the anisotropy of the Seebeck tensors.