Effect of chemical nature of atoms on the electronic, dielectric, and dynamical properties of <i>ABX</i>₃ halide perovskite

Abstract

Abstract First‐principles calculations within density functional theory were performed on a series of halide perovskite compounds ABX 3 ( A : Cs or Rb ; B : Pb or Sn ). Their electronic structure, lattice dynamics, and dielectric properties were studied in relationship with the change in atom species at each one of the three inequivalent crystallographic sites, to explain the origin of these properties. Thus, the variation of the bandgap with the overlap between the B cation lone pair and the electronic states of halide atoms, as well as with the distortion of the BX 6 octahedra network is discussed. It is shown that the vibrational modes, phonon frequencies, atomic displacements, and the possible ferroelectric instability in these compounds are dependent on masses of atoms, volume of AX 12 polyhedron, as well as on streoactivity of Pb lone pair. Also, the Born effective charges, dielectric constant, spontaneous polarization, and infrared spectra are calculated. The relation between these dielectric properties and the ions dynamics is discussed.