Temperature dependent dielectric mechanism of lead-free double perovskite Sr₂YbNbO₆

The double perovskite Sr₂YbNbO₆ (Strontium ytterbium niobium oxide, SYN) has been synthesized by solid-state ceramic processing technique. SYN crystallizes in monoclinic structure with P2₁/n space group. SYN is polycrystalline in nature with grain size ~ 2.38 μm. The Raman spectrum analysis of SYN reveals the presence of 24 Raman active modes. The bands associated with the bending and stretching vibrations of the YbO₆ and NbO₆ octahedra has been analysed using its FTIR spectrum. The optical band gap of SYN has been obtained to be 3.08 eV. The dielectric properties of the sample have been investigated in between 50 Hz to 1 MHz frequency and 303‒513 K temperature. The dielectric relaxation of SYN is polydispersive in nature and has been analysed using the Cole-Cole model. The activation energy of SYN is 0.52 eV which points towards the conduction associated with the hopping of p-type polaron.