First-principles investigation of intrinsic dielectric response in Ba(B′1/3B″2/3)O3 with B′ as transition metal cations

•Ba(Mn1/3B″2/3)O3 is Mott–Hubbard insulator characterized by Mn(eg)-B″(t2g) gap.•Band gap of Ba(Ni1/3B″2/3)O3 is mixture of charge-transfer and Mott–Hubbard type.•The calculated dielectric constants are in agreement with the experimental values.•Substitution of Ni for Mn raises frequencies of the dominant Eu phonons.•Dielectric contribution from B″ and O2 increases with increase of dielectric loss.

The intrinsic dielectric response and lattice dielectric properties of 1:2 ordered Ba(B′1/3B″2/3)O3 (B′ = Mn, Ni; B″ = Ta, Nb) materials are investigated using density functional theory within the GGA + U method. The calculated dielectric constants are in excellent agreement with the experimental values. The influences of different B′ and B″ ions on frequencies, oscillator strengths, and eigenvectors of their dominant IR phonons are analyzed in detail. We find that the dielectric contributions to ε11 from B″ and O2 ions increase with enhancement of their dielectric losses, which is well consistent with the experimental IR spectra for Ba(Mg 1/3B″2/3)O3 compounds.