Band gap narrowing and electrical properties of (1-x)BaTiO3-xSrFe0.5Nb0.5O3 lead-free ceramics

Abstract

The composite materials in the form of (1-x)BaTiO 3 -xSrFe 0.5 Nb 0.5 O 3 ((1-x)BT-xSFN) are synthesized via the solid-state reaction route. Structure, optical behaviors and electrical properties of (1-x)BT-xSFN are studied. It can be noted that the structure of the synthesized solid solution changes from the tetragonal phase to the cubic phase with increase of x-value. Due to the increase in content of double perovskite SFN, the optical band gaps of doped BT decrease to a minimum of 2.66 eV, which is smaller than that of pure BT (3.21 eV). However, the ferroelectric property deteriorates with the addition of dopants, which result from the lattice distortion caused by the substitution of Sr 2+ and Fe 3+ /Nb 5+ for Ba 2+ and Ti 4+ , respectively. These results provide new insights into the control of the structure, optical behaviors and ferroelectric properties in BT-based oxides.

Ni2+doping effect on potassium barium titanate nanoparticles: enhancement optical and dielectric properties

“…This behavior was interpreted through the doping mediation mechanisms [31]. Many studies have verified that in BaTiO 3 , the conduction and valence bands are created throughO-2p orbital and Ti-3d orbital, respectively [34].…”

“…Lead-free (ABO 3 -type) perovskite materials based on BaTiO 3 have achieved some interest where the ABO 3 -type perovskite materials with physical properties are controlled via A and B site cations and have an octahedral structure [31]. The valence and conduction band of ABO 3 -perovskite are collected of d orbital of the transition metal ions and the O-2p orbital.…”

“…The valence and conduction band of ABO 3 -perovskite are collected of d orbital of the transition metal ions and the O-2p orbital. Also, their bandgap relates to the energy difference between their valence and conduction bands [31,32].…”

“…The lowering the conduction band energy, the larger the electronegativity of ions, [34], electronegativity of Ti = 1.54, and Ni = 1.91 [34]. In K(1-x)BaTiO 3 -xNiO nanoparticles, as the electronegativity of the (Ni 2+ ) ion is larger than that of the (Ti 4+ ) ion, and the Ni-3d orbital is lower than Ti-3d orbital in energy, the energy band gap of doped KBaTiO 3 materials forced into narrowing [31]. Also, the addition of Ni 2+ was introduced at the B-site of KBaTiO 3 as a substituting of Ti 4+ .…”