Structural, dielectric and impedance studies of polycrystalline La0.6Gd0.2Ca0.2MnO3
24 May 2016-Vol. 1731, Iss: 1, pp 050127
TL;DR: In this article, powder XRD, dielectric studies and impedance studies were performed on polycrystalline materials of Gd doped La1-xCaxMnO3.
Abstract: Polycrystalline materials of Gd doped La1-xCaxMnO3 were prepared by Sol-Gel technique using citric acid as a chelating agent at 9000 C. The single phase formation of Gd doped LCMO were determined by Powder XRD, dielectric studies and impedance studies is investigated. The existence of dielectric relaxation and release of space charges were observed in the dielectric constant and real part of impedance plots respectively. The shift in the peaks for imaginary part of impedance revealed the existence of relaxation process due to oxygen vacancy. The existence of single semicircle in the cole-cole plot confirms the dielectric relaxation in the prepared sample.
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TL;DR: In this article, the energy band gap obtained from Diffuse Reflectance Spectroscopy clearly suggests that the band gap of nanoparticles (2.06eV) is larger than that of the microparticles (1.58eV).
Abstract: In the proceeding way of material research in the field of manganites, LCMO micro and nanoparticles are synthesized via. the solid-state reaction route, glycine-nitrate combustion method respectively. The phase confirmation is done by XRD, FT-IR technique and the surface morphology viewed by Scanning Electron Microscope (SEM). The energy band gap obtained from Diffuse Reflectance Spectroscopy clearly suggests that the band gap of nanoparticles (2.06eV) is larger than that of the microparticles (1.58eV). Both samples comprise of wide band-gap semiconductor, so the refractive index is calculated using Herve and Vandamme relation. The impedance spectroscopy and dielectric properties of the two samples are studied from room temperature to 100oC over the frequency range 102-106 Hz. The Cole-Cole plot of impedance is fitted using the RC-Circuit R(QgRg)(QgbRgb)(CRin). The dielectric property is found to be enhanced in nanoparticles as compared to the microparticles. The findings suggest the nanoparticles be promising candidates in the field of high frequency devices as compared to micro.
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References
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TL;DR: In this paper, the structural, magnetic and transport properties of LCSMO thin films were systematically studied and a strong coupling between lattice and physical properties was found. But, the results were limited to the case of Si substrates.
55 citations
TL;DR: In this article, the synthesis of ZnMn2O4, transitional metal oxide by sol-gel method was reported and structural and morphological properties were confirmed using various characterization techniques namely XRD, FT-IR and SEM with EDX.
Abstract: In this present study, we have reported the synthesis of ZnMn2O4, transitional metal oxide by sol–gel method. The structural and morphological properties are confirmed using various characterization techniques namely XRD, FT-IR and SEM with EDX. Dielectric studies of ZnMn2O4 are measured at the frequency varying from 50 Hz to 5 MHz for the temperature range of 303–573 K. The temperature dependent electrical parameters like impedance and modulus exhibit a strong correlation with the grains, grain boundaries and space charge effects in the synthesized material. Diffusion of oxygen vacancies in the dipoles and defects in the material due to oxygen vacancy complexes are investigated by the activation energy obtained from Arrhenius plot. It was found that the relaxation process was dominated by the hopping mechanism between the Mn3+ and Mn4+. Nyquist plot of impedance was attributed to the existence of space charge interface, grain boundary and grain conduction mechanism of the material.
29 citations
TL;DR: In this paper, dielectric studies on Ca 0.9Nd0.1Ti0.9Al 0.1O3−δ single crystals grown by the optical floating zone technique in the temperature range from room temperature to 660 K were performed.
Abstract: We herein report dielectric studies on Ca0.9Nd0.1Ti0.9Al0.1O3−δ single crystals grown by the optical floating zone technique in the temperature range from room temperature to 660 K. Two dielectric anomalies were observed at ∼436 K and 520 K, which correspond to relaxor-like behaviour due to Maxwell–Wagner relaxations and conduction relaxation associated with doubly ionized oxygen vacancies respectively. The presence of Ti3+ for charge carrier hopping and oxygen vacancies is confirmed by X-ray photoelectron spectroscopy analysis.
29 citations
TL;DR: An epitaxial La0.8Ca0.2MnO3/LaAlO3 (LCMO/LAO) thin film was fabricated using the pulsed laser deposition (PLD) technique to evaluate the magnetoresistance (MR) and temperature coefficient of resistance (TCR).
22 citations
TL;DR: In this paper, perovskite-type (Ca1−xLax) powders were synthesized using a Pechini-type polymerized complex route, and (Ca 1−x Lax)MnO3 ceramics with a high relative density (85.6% −98.5%) were fabricated using a planetary mill and cold-isostatic pressing (CIP) in order to improve the electrical and thermoelectric properties.
Abstract: Perovskite-type (Ca1−xLax)MnO3 powders were synthesized using a Pechini-type polymerized complex route, and (Ca1−x Lax)MnO3 ceramics with a high relative density (85.6%–98.5%) were fabricated using a planetary mill and cold-isostatic pressing (CIP) in order to improve the electrical and thermoelectric properties. The electrical conductivity (σ) was independent of both x and the temperature, and the relationship between log σT vs. 1000/T was linear. The Seebeck coefficient (S) was negative, and the absolute value of the Seebeck coefficient increased with temperature and decreased with increases of x. The highest value of the power factor (S2σ) was 3–4 × 10−4 W/(K2·m) for the (Ca0.96La0.04)MnO3 ceramic.
21 citations