Study of the electrical and dielectric measurements of a rare-earth doped perovskite La0.6Nd0.1Sr0.3Mn0.7Ti0.3O3 (original) (raw)
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Electrical conductivity and dielectric analysis of La 0.75 (Ca,Sr) 0.25 Mn 0.85 Ga 0.15 O 3 perovskite compound a b s t r a c t In the present study the tool of impedance spectroscopy was utilized to characterize dielectric behavior of AMn 0.85 Ga 0.15 O 3 (A = La 0.75 Ca 0.08 Sr 0.17) composition synthesized by the solid-state reaction. The complex impedance has been investigated in the temperature range 100–360 K and in the frequency range 40 Hz–2 MHz. The Z 0 and Z 00 versus frequency plots were found to exhibit a semi-circular arc described by an electrical equivalent circuit. The conductivity spectra have been investigated by the Jonscher universal power law: r(x) = r dc + Ax n , where x is the frequency of the ac field, and n is the exponent. The activation energy obtained both from dc conductivity and modulus spectrum are very similar, and hence the relaxation process may be attributed to the same type of charge carriers.
Electrical conductivity and complex impedance analysis of 20% Ti-doped La0.7Sr0.3MnO3 perovskite
Journal of Magnetism and Magnetic Materials, 2007
Electrical properties of Ba 2 CrMo 0.8 W 0.2 O 6 double perovskite were investigated using admittance spectroscopy technique. According to impedance analysis, the material was modeled by an electrical equivalent circuit. Such analysis proves the presence of relaxation phenomenon in the compound. We also found that ac conductivity follows the Jonscher universal power law. Conduction process is found to be dominated by the thermally activated small polaron (SPH). The activation energy values, inferred from dc conductivity and from the temperature dependence of relaxation time, are closed to each other. Such result indicates that conduction process and relaxation phenomenon are related to the same defect.
Structural and Electrical Properties of Perovskites
2020
Abstract: Nanocrystalline and nanocomposites of Sr doped La 1-xSrxMnO3 (x=0,0.3) were synthesised by the sol –gel citrate method. Structural and dielectric analysis were performed for synthesized nanocomposites La1-xSrx MnO3.The XRD of La 1-xSr xMnO3 (x=0,0.3)shows orthorhombic structure. Dielectric constant ( ε’ and ε”) of La 1-xSrxMnO 3 (x=0,0.3) were measured as a function of frequency in the range 42 Hz to 500 MHz and the temperature range 30 to700°C. A ferroelectric like dielectric constant ranging from 10 4 to10 6 was obtained for both. AC conductivity has been studied as a function of frequency and temperature to understand the conduction mechanism.
Structural and dielectric properties of La0.8Te0.2MnO3
Solid State Communications, 2013
We have studied the structural and dielectric properties of La 0.8 Te 0.2 MnO 3 pervoskite compound, has a rhombohedral structure with space group R-3c, at room temperature. Infrared spectrum shows two active bands located at 611 and 410 cm À 1 , which can be ascribed to the internal stretching and bending phonon modes. The additional bands observed at 925, 969 and 1383 cm À 1 are attributed to the multiphonon scattering. The dielectric constant e 0 shows a step like relaxation behaviour and has been discussed with in the frame work of the Kramers-Kronig transformation model. The ac conductivity follows a universal dielectric response (UDR), and the results were discussed and fitted with the Jump relaxation model (JRM). The occurrence of giant or colossal dielectric constant is most likely due to electrode polarization or interface polarization effect. The depletion layers are arising due to the formation of Schottky barriers at the metallic contacts of semiconducting samples, which may be formed by grain boundaries, can give rise to Maxwell-Wagner type relaxation and apparently very high dielectric constants.
Journal of Materials Science: Materials in Electronics, 2019
La 0.75 Ba 0.25−x Sr x FeO 3 perovskite compounds with different strontium concentrations were synthesized via the sol-gel method. X-ray diffraction (XRD) data indicated that all obtained samples crystallize in the orthorhombic structure with the Pnma space group. The dielectric properties of these samples, using complex impedance spectroscopy technique have been carried out as function of frequency and temperature as well. An adequate electrical equivalent circuit has been used to evaluate the grain and grain boundary contributions in complex impedance results. Furthermore, the AC conductivity spectra obey to Jonscher's universal power law. The behavior of the exponent "S" suggests that the conduction mechanism follows the overlapping large polaron tunneling (OLPT) process for x = 0.05, while for both compounds x = 0.10 and x = 0.15 the nonoverlapping small polaron tunneling (NSPT) is the applicable model. The behavior of ε″ as a function of both frequency and temperature has been described by Giuntini model.
Journal of Power Sources, 2007
In this paper, the structural and transport properties of selected La 1−x Sr x Co 0.2 Fe 0.8 O 3 (LSCF) perovskites and La 0.6 Sr 0.4 Co 0.2 Fe 0.6 Ni 0.2 O 3 (LSCFN64262) perovskite are presented. Crystal structure of the samples was characterized by means of X-ray studies with Rietveld method analysis. DC electrical conductivity and thermoelectric power were measured at a wide temperature range (80-1200 K) in air. For La 0.2 Sr 0.8 Co 0.2 Fe 0.8 O 3 (LSCF2828) and La 0.4 Sr 0.6 Co 0.2 Fe 0.8 O 3 (LSCF4628) perovskites a maximum observed on electrical conductivity dependence on temperature exists at about 750 K. It can be associated with an appearance of oxygen vacancies and implies a mixed ionic-electronic transport. A growing amount of oxygen vacancies at higher temperatures causes a decrease in the electrical conductivity due to a recombination mechanism associated with lowering of the average valence of 3d metals. A similar characteristic was found for LSCFN64262 perovskite, which also exhibits a relatively high electrical conductivity.
2020
Nanocrystalline and nanocomposites of Sr doped La 1-xSrxMnO3 (x=0,0.3) were synthesised by the sol-gel citrate method. Structural and dielectric analysis were performed for synthesized nanocomposites La1-xSrx MnO3.The XRD of La 1-xSr xMnO3 (x=0,0.3)shows orthorhombic structure. Dielectric constant (ε' and ε") of La 1-xSrxMnO 3 (x=0,0.3) were measured as a function of frequency in the range 42 Hz to 500 MHz and the temperature range 30 to700°C. A ferroelectric like dielectric constant ranging from 10 4 to10 6 was obtained for both. AC conductivity has been studied as a function of frequency and temperature to understand the conduction mechanism.
Phase Transitions, 2019
We have investigated the dielectric properties of La 0.67 Sr 0.16 Ca 0.17 MnO 3 (LSCMO) perovskite synthesized by the solid-state reaction method. X-ray diffraction analysis revealed that this sample crystallizes in the distorted rhombohedral system with R 3c space group. Experimental results reveal that the real and imaginary dielectric permittivity (1 ′ and 1 ′′), and dielectric loss tangent (tan d) parameters have strong frequency-dependence. The variation of dielectric permittivity and tangent loss (tan d) with frequency show a dispersive behavior at low frequencies and is explained on the basis of the Maxwell-Wagner model and Koop's theory. It was found that LSCMO ceramics exhibited very high dielectric constant (1 ′ ≈ 10 4) values compared to traditional ferroelectric materials. Electric modulus formalism has been employed to study the relaxation dynamics of charge carriers. The activation energy deduced from analysis of the imaginary part of electric modulus is found to be ∼46.33 meV. The apparent density of sintered pellets were determined using the Archimedes principle. Thus, the value of the density for this compound was 6.155 g.cm −3
Impedance spectroscopy and conduction mechanism in La0.8Pb0.2Fe0.75Mg0.25O3 perovskite
Chemical Physics Letters, 2021
Polycrystalline (Bi 0.6 K 0.4) (Fe 0.6 Nb 0.4)O 3 material has been prepared using a mixed-oxide route at 950 1C. It was shown by XRD that at room temperature structure of the compound is of single-phase with hexagonal symmetry. Some electrical characteristics (impedance, modulus, conductivity etc.) were studied over a wide frequency (1 kHz-1 MHz) and temperature (25-500 1C) ranges. The Nyquist plot (i.e., imaginary vs real component of complex impedance) of the material exhibit the existence and magnitude of grain interior and grain boundary contributions in the complex electrical parameters of the material depending on frequency, input energy and temperature. The nature of frequency dependence of ac conductivity follows Joncher's power law, and dc conductivity follows the Arrhenius behavior. The appearance of P-E hysteresis loop confirms the ferroelectric properties of the material with remnant polarization (2P r) of 1.027 mC/cm 2 and coercive field (2E c) of 16.633 kV/cm. The material shows very weak ferromagnetism at room temperature with remnant magnetization (2M r) of 0.035 emu/gm and coercive field (2H c) of 0.211 kOe.
Electrical Conduction in Nano-Structured La0.9Sr0.1Al0.85Co0.05Mg0.1O3 Perovskite Oxide
Journal of the American Ceramic Society, 2005
oxide powder was synthesized by a citrate-nitrate auto-ignition process and characterized by thermal analysis, X-ray diffraction, and impedance spectroscopy measurements. Nanocrystalline (50-100 nm) powder with perovskite structure could be produced at 9001C by this process. The powder could be sintered to a density more than 96% of the theoretical density at 15501C. Impedance measurements on the sintered samples unequivocally established the potential of this process in developing nanostructured lanthanum aluminate-based oxides. The sintered La 0.9 Sr 0.1 Al 0.85 Co 0.05 Mg 0.1 O 3 sample exhibited a conductivity of 2.40 Â 10 À2 S/cm in air at 10001C compared with 4.9 Â 10 À3 S/cm exhibited by La 0.9 Sr 0.1 Al 0.85 Mg 0.15 O 3 .