Prediction of the structural, electronic, and piezoelectric properties of narrow-bandgap compounds FeVX (X = P, As, Sb)

Abstract

A systematic theoretical investigation is carried out on the possible piezoelectric effect in the half-Heusler FeVX (X = P, As, Sb) compounds crystallizing in the cubic MgAgAs-type structure C1b by combining density functional theory (DFT) and perturbation theory (DFPT) based on the pseudopotential plane wave (PP-PW) method implemented in the ABINIT code. The ground-state properties such as the lattice constants, and the bulk modulus and its pressure derivative are obtained using both the local density approximation and the generalized gradient approximation for the exchange–correlation functional, and the results are compared with other studies. The results for the electronic properties reveal that all the compounds exhibit semiconducting behavior with a narrow indirect bandgap. In addition, the elastic, dielectric, and piezoelectric constants are computed using density functional perturbation theory. The title compounds are found to exhibit a good electromechanical coupling coefficient (k14). No experimental or theoretical data are available for their piezoelectric properties. Thus, the results of this study can be considered to represent theoretical predictions of the properties of new piezoelectric half-Heusler compounds that can be selected based on the values of their piezoelectric coefficient (e14), which are greater than the value of 0.16 C/m2 measured empirically for GaAs. Finally, the results presented herein shed light on the use of such piezoelectricity as a possible effect in various applications such as micromechanical actuators, sensors, and self-powered devices.