Intragrain electrical inhomogenities and compositional variation of static dielectric constant in LaMn_{1-x}Fe_xO_3
arXiv:0901.4442 · doi:10.1088/0022-3727/42/9/092004
Abstract
Bulk dc resistivity and dielectric constant measurements with temperature and frequency have been performed in LaMn_{1-x}Fe_xO_3 (0 <= x <= 1.0) as a result of Fe substitution both for the as-synthesized and oxygen annealed samples. Temperature dependence of real part of dielectric constant at different frequencies show a frequency and temperature independent value (epsilon_s) at low temperature for x >= 0.15 where epsilon_0 rises with x reaching a maximum at x = 0.5 and then it decreases sharply at x = 0.70 showing a further increasing trend with the further increase in x. The sharp drop of epsilon_s at x = 0.70 is correlated with the structural change from rhombohedral to orthorhombic structure. A considerable increase of epsilon_s ~ 43% is observed for an increase of x from 0.15 to 0.50. Furthermore, epsilon_s is increased considerably (up to ~ 17% at x = 0.5) due to the oxygen annealing for x <= 0.50. The low temperature resistivities satisfying Variable Range Hopping model are found to be related with the increase of epsilon_s with x for x <= 0.50. The analysis of the complex impedance and modulus planes at low temperature indicates the electrical inhomogeneities in the grain interior of the compounds.
References in corpus (8)
- Non-intrinsic origin of the Colossal Dielectric Constants in CaCu3Ti4O12
- Low-Temperature Permittivity of Insulating Perovskite Manganites
- Polaron relaxation and hopping conductivity in LaMnFeO
- Colossal magnetocapacitance and scale-invariant dielectric response in phase-separated manganites
- Magnetic phases evolution in the LaMn1-xFexO3+y system
- Exchange bias with Fe substitution in LaMnO_3
- Giant Dielectric Permittivity of Electron-Doped Manganite Thin Films, Ca(1-x)La(x)MnO(3) ($0<= x<= 0.03)
- Doping Dependence of Polaron Hopping Energies in La(1-x)Ca(x)MnO(3) (0<= x<= 0.15)