Origin of colossal dielectric response in LaFeO3

Dielectric and electrical studies of Pr3+ doped nano CaSiO3 perovskite ceramics

“…This thin layer of relatively large resistance offers higher capacitance owing to the inverse proportionality between the capacitance C and thickness d of the layer. This high A c c e p t e d M a n u s c r i p t 8 resistance and capacitance associated with the grain electrode contact and grain boundaries cause their response to lie at lower frequencies compared to that of grains [5].…”

“…However, use of ferroelectrics is limited by the strong temperature dependence of dielectric constant near transition temperature T C . In the recent years, a large number of non-ferroelectric materials such as CaCu 3 Ti 4 O 12 (CCTO) [1][2][3], BaFe 1/2 Nb 1/2 O 3 [4], LaFeO 3 [5] and Pr 0.6 Ca 0.4 MnO 3 [6] have been found to possess colossal values of the dielectric constant with a weak temperature dependence. Tsang-Tse Fang et al have investigated the role of Si ions in the microstructure change, the electrical conduction and the dielectric responses of CaSiO 3 doped CCTO [7].…”

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

“…Ever since, these material suffers multiple valance (Fe 3þ /Fe 2þ , Ti 4þ /Ti 3þ , Mn 3þ /Mn 4þ ) which can be correlated with oxygen vacancies is a common feature for the CDC effect in transition metal ions. [5][6][7][8][9][10][11] Worthwhile, LaFeO 3 ceramic also exhibit CDC up to 380 K. For the first time, Idress et al 12 reported a giant dielectric constant behavior in LaFeO 3 , which was an extrinsic effect due to Maxwell-Wagner relaxation. 11,12 Despite, it has few limitations, such as high leakage current, intrinsic antiferromagnetic and weak ME coupling at RT, which can hamper the large scale applications.…”

Electric Conductivity of (Bi1-xLaxFeO3)0.5(PbTiO3)0.5Ceramics Obtained from Mechanosynthesized Nanopowders

“…The heterogeneity of BFLOPT ceramics is rather complex and we have to consider that as consisting of highly-conducting grains separated by grain boundaries with high electric resistivity [27]. [29]. In the text above, vacancy is denoted as empty square, hole as h and electron as e. Fig.…”

“…At higher frequencies the conductivity is mainly due to the interior of the grains with a structural disorder and the σ ac (f ) values in the frequency range from ≈ 1 kHz to ≈ 1 MHz at room temperature are nearly proportional to the frequency f . It should be observed that the energy levels of electrons and holes in the material are localized on specic atoms/vacancies which can appear in dierent valence states, therefore we would like to consider thermally activated motion of electrons and holes to adjacent sites as small polaron hopping [28,29]. An increase in the conductivity at higher frequencies may be related to a contribution of another process for instance It should be observed that the material exhibits also ferroelastic properties and structural changes in the interior of the grains modify also the properties of the grain boundaries.…”