Origin of giant dielectric permittivity and weak ferromagnetic behavior in (1−x)LaFeO₃−xBaTiO₃ (0.0 ≤ x ≤ 0.25) solid solutions

Abstract

The solid solutions of (1 À x) LaFeO 3 -xBaTiO 3 (0.0 x 0.25) have been synthesized successfully by the conventional solid-state reaction method. Room temperature (RT) X-ray diffraction studies reveal the stabilization of orthorhombic phase with Pbnm space group. Complete solubility in the perovskite series was demonstrated up to x ¼ 0:25. The dielectric permittivity shows colossal dielectric constant (CDC) at RT. The doping of BaTiO 3 in LaFeO 3 exhibit pronounced CDC up to a composition x ¼ 0:15, further it starts to decrease. The frequency-dependent dielectric loss exhibits polaronic conduction, which can attribute to presence of multiple valence of iron. The relaxation frequency and polaronic conduction mechanism was shifted towards RT as function of x. Moreover, large magnetic moment with weak ferromagnetic behavior is observed in doped LaFeO 3 solid solution, which might be the destruction of spin cycloid structure due to insertion of Ti in Fe-O-Fe network of LaFeO 3 .

Origin of Colossal Dielectric Permittivity in (Nb + Ga) Co-Doped TiO2 Single Crystals

“…Materials with colossal permittivity (CP > 1000) have attracted increasing attention due to their multi-functionality and possible miniaturization in high-speed integrated circuits and energy density storage devices. − Numerous methods have been so far used for designing large dielectric constant materials. Several materials with colossal dielectric permittivity exist, including perovskite ferroelectric oxide BaTiO 3 , , CaCu 3 Ti 4 O 12 (CCTO), and doped NiO . The perovskite-type ferroelectric oxide BaTiO 3 possesses a CP ≈ 5000, originating from the internal barrier layer capacitance (IBLC) effect .…”

“…1−3 Numerous methods have been so far used for designing large dielectric constant materials. Several materials with colossal dielectric permittivity exist, including perovskite ferroelectric oxide BaTiO 3 , 4,5 CaCu 3 Ti 4 O 12 (CCTO), 6 and doped NiO. 7 The perovskitetype ferroelectric oxide BaTiO 3 possesses a CP ≈ 5000, originating from the internal barrier layer capacitance (IBLC) effect.…”