scholarly journals The comparative study of the structural and the electrical properties of the nano spinel ferrites prepared by the soft mehanochemical synthesis

2014 ◽  
Vol 46 (2) ◽  
pp. 235-245 ◽  
Author(s):  
D.L. Sekulic ◽  
Z.Z. Lazarevic ◽  
C. Jovalekic ◽  
A. Recnik ◽  
M. Romcevic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Complex Impedance ◽  
Spinel Ferrites ◽  
Spectroscopy Analysis ◽  
Electrical Conductivities ◽  
Increasing Temperature ◽  
The Comparative Study ◽  
Hopping Model ◽  
Impedance Spectroscopy Analysis

Nano spinel ferrites MFe2O4 (M=Ni, Mn, Zn) were obtained by soft mechanochemical synthesis in a planetary ball mill. The appropriate mixture of oxide and hydroxide powders was used as initial compounds. All of this mixture of powders was mechanically activated, uniaxial pressed and sintered at 1100?C/2h. The phase composition of the powders and sintered samples were analyzed by XRD and Raman spectroscopy. Morphologies were examined by SEM. In this study, the AC-conductivity and DC-resistivity of sintered samples of MFe2O4 (M= Ni, Mn, Zn) ferrites were measured at different frequencies and at room temperature. The values of the electrical conductivities show an increase with increasing temperature, which indicated the semiconducting behavior of the studied ferrites. The conduction phenomenon of the investigated samples could be explained on the basis of hopping model. The complex impedance spectroscopy analysis was used to study the effect of grain and grain boundary on the electrical properties of all three obtained ferrites

scholarly journals Microstructure and electric response of Li,Sn co-doped NiO ceramics

2019 ◽  
Vol 13 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Jiecheng Zeng ◽  
Tusheng He ◽  
Yang Liu
Keyword(s):  
Grain Boundary ◽  
Polarization Effect ◽  
Room Temperature ◽  
Electric Response ◽  
Frequency Range ◽  
Spectroscopy Analysis ◽  
Frequency Independent ◽  
Increasing Temperature ◽  
Impedance Spectroscopy Analysis ◽  
Co Doped

Phase composition, microstructure and electric response of Li0.05SnxNi0.95 - xO (x = 0, 0.025, 0.05, 0.1) ceramics were systematically investigated. Colossal dielectric permittivity (>5000) is observed in the frequency range of 102-105 Hz at room temperature which becomes highly frequency-independent with increasing temperature. Secondary Sn-rich phase is detected in the grain boundary regions and it has a remarkable influence on the dielectric properties. Impedance spectroscopy analysis demonstrates that the microstructure is electrically heterogeneous, consisting of semiconducting grain and insulating grain boundary. Defect dipoles or polyvalent cations induced at high temperature may activate an electron hopping process under electric field, resulting in the enhancements of grain conductivity and polarization effect. This behaviour should be considered as the origin of the observed dielectric response.

Structural and electrical properties of KCa2Nb5O15 ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Banarji Behera ◽  
Pratibindhya Nayak ◽  
Ram Choudhary
Keyword(s):  
Electrical Properties ◽  
Temperature Variation ◽  
Electrical Transport ◽  
Room Temperature ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Transport Processes ◽  
Relaxation Processes ◽  
Orthorhombic Crystal Structure ◽  
Grain Distribution

AbstractA polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

Conductive Metakaolin Geopolymer with Steel Microfibres​

2021 ◽  
Vol 321 ◽  
pp. 59-64
Author(s):  
Cecílie Mizerová ◽  
Ivo Kusák ◽  
Pavel Rovnaník ◽  
Patrik Bayer
Keyword(s):  
Electrical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Multifunctional Composites ◽  
Spectroscopy Analysis ◽  
Sem Imaging ◽  
Metakaolin Geopolymer ◽  
Fibre Matrix ◽  
Alkali Activated ◽  
Impedance Spectroscopy Analysis

Research of alkali-activated materials and geopolymers suggests their increased ability to transfer the electric charge thus indicating their suitability for self-sensing and other multifunctional composites. In this paper, the electrical properties of metakaolin geopolymer are enhanced by the incorporated steel microfibres that also improve the mechanical and fractural properties of the composite. Selected electrical properties of metakaolin geopolymer mortars with steel microfibres (up to 30 % of metakaolin wt.) were assessed via impedance spectroscopy analysis and followed by testing their compressive and flexural strength. Mercury intrusion porosimetry and SEM imaging enabled to characterize the binder microstructure and quality of fibre-matrix bonding.

scholarly journals Structural, dielectric and impedance spectroscopy analysis of Ba5CaTi1.94Zn0.06Nb8O30 ferroelectric ceramic

RSC Advances ◽  
2020 ◽  
Vol 10 (47) ◽  
pp. 28007-28018
Author(s):  
Amine Bendahhou ◽  
Karim Chourti ◽  
Rachid El Bouayadi ◽  
Soufian El Barkany ◽  
Mohamed Abou-Salama
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Tungsten Bronze ◽  
Ferroelectric Ceramic ◽  
Spectroscopy Analysis ◽  
Impedance Spectroscopy Analysis ◽  
Co Doped

In this work, Zn co-doped tungsten bronze having nominal formula Ba5CaTi1.94Zn0.06Nb8O30 has been synthesized and systematically studied for structure, dielectric and electrical properties.

Synthesis and Electrical Properties of Mo-ZrO2 Cermet

2011 ◽  
Vol 311-313 ◽  
pp. 2121-2126
Author(s):  
Ji Fang Xu ◽  
Gong Yuan Liu ◽  
Lei Tang ◽  
Jie Yu Zhang ◽  
Chang Jie
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Electrical Properties ◽  
Room Temperature ◽  
Optical Microscope ◽  
Metal Phase ◽  
Phase Zone ◽  
Ceramic Phase ◽  
Mo Content ◽  
Increasing Temperature

Under the protected condition of the purified argon atmosphere, Mo-ZrO2cermets were sintered by Mo powder and ZrO2powder at 1873K for 2 hours. Mircostructure of cermets were observed by means of XRD, optical microscope and SEM anslysis. Electrical properties of sintered samples with different Mo content and temperature were measured using DC four-electrode method. The results showed that metal phase and ceramic phase were independent of each other. With the reduction of Mo content, Mo metal phase as the continuous network structure is dispersedly distributed in the ceramic phase zone. The electrical conductivity of cermets at room temperature increased with decreaseing of the Mo content. The trend that the high-temperature electrical conductivity of cermets changed with the Mo content is the same as the trend that at the room temperature. When the Mo content is greater than 40%, the high-temperature electrical conductivity increased linearly with increasing temperature. The electrical conductivity of 40mol-% Mo-ZrO2reached the peak at 1223K and 1473K.

Microstructural Correlation with Electrical Properties for Y2O3 Doped CeO2 Thin Films

1997 ◽  
Vol 500 ◽  
Author(s):  
Chunyan Tian ◽  
Siu-Wai Chan
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Complex Impedance ◽  
Fused Silica ◽  
X Ray Diffraction ◽  
Spectroscopy Analysis ◽  
Boundary Conductivity ◽  
Bulk Ceramic ◽  
Transmission Electron ◽  
Beam Deposition

ABSTRACTHigh quality textured 0.58% Y2O3 doped CeO2 films with (001), (111)/(001) and (110) were prepared using an e-beam deposition technique on substrates of (001) LaAlO3, r-cut sapphire, and fused silica, respectively. The composition and stoichiometry of the films were verified by Rutherford backscattering spectroscopy analysis. Both x-ray diffraction and transmission electron microscopy analyses gave consistent microstructural information. Complex impedance measurements have been performed to study the electrical properties of these films as a function of temperature. The conductivities of the films were dominated by grain boundaries of high conductivities as compared to that of the bulk ceramic of the same dopant concentration. The activation energies for the film conductivities were only slightly higher than that for the bulk lattice conductivities, but much lower than that for the bulk grain boundary conductivity. These results have been discussed in terms of the differences of the grain size and grain boundary microstructures between the films and the bulk ceramics.

scholarly journals Electrical Properties of Double Perovskite LaPbFeTiO6 Synthesized by Sol-Gel Method

2021 ◽  
Author(s):  
K. Iben Nassar ◽  
M. Slimi ◽  
N. Rammeh ◽  
Manuel. P. F. Graça
Keyword(s):  
Electrical Properties ◽  
Electrical Impedance ◽  
Sol Gel ◽  
Complex Impedance ◽  
Double Perovskite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size ◽  
Increasing Temperature ◽  
Electronic Field

Abstract The double perovskite structure is interesting for many researches in various fields of physics and their technological applications. The LaPbFeTiO6 (LPFTO) compound is a very important for many technologies because it has dielectric and electrical properties. It has made an attractive semiconductor material for the electronic field, such as the realization of filters or capacitors. In this work, LaPbFeTiO6 was prepared by the sol-gel method.The structural, morphological and electrical properties of this sample were studied using different techniques. X-ray diffraction analysis, the sample crystallized in the rhombohedral system with space group R C. The surface of the sample and the average grain size were examined by scanning electron microscope (SEM). The electrical conductivity and dielectric characterizations were studied as a function of frequency and temperature (200-380K) by impedance spectroscopy. Indeed, the dielectric constant increases with increasing temperature. The AC conductivity obeys the Jonscher power law. The activation energy obtained from the complex impedance and the conductivity are close. The frequency dependence of the electrical impedance shows the existence of a relaxation phenomenon.

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